Re: [RE-wrenches] power factor

[Darryl Thayer]

I have found that many inverters will have a poor power factor when producing 
low power, and the power factor improves with load.  if there are other things 
on your load it can effect the power factor./   I have also seen very low power 
factor when motors run unloaded.  I remember a gas dryer with no clothes and 
the power factor was 0.24

Power Factor is like a spring, a piece of equipment will draw current like 
compressing a spring and then send it back, so the utility has current flowing 
in the wires but no net work or no kWh  
DT 


 From: "toddc...@finestplanet.com" 
To: RE-wrenches  
Sent: Monday, May 7, 2012 11:47 PM
Subject: Re: [RE-wrenches] power factor
   
excellent replies to yes, a complicated issue. i think i finally understand 
this. thank you kent and dan! 
  
todd 
  
  
  
On Monday, May 7, 2012 9:02pm, "Exeltech"  said:

 
Hello Todd,

The short answer to your "is this a concern?" query, is "no".

Reactive power is one of the more complex aspects of electric power, and
certainly one of the most misunderstood.  It can and does involve inductive
loads (e.g. motors), capacitive loads (e.g. some types of power supplies),
and non-linear loads (e.g. switch-mode power supplies, dimmers, etc.).

You likely know (or should know) "power factor" is the ratio of real power to
reactive power consumed by a load.  Grid-tie inverters generate "real" watts,
which are then coupled to the grid.  When a reactive load in your home is
consuming power, and you provide real watts to the load from the inverter,
this changes the ratio of real to apparent power consumed by the load as
seen by the utility company.

Dividing real power by  apparent power results in a unit-less value between 0
and 1 that describes this ratio.

Let's say a load in your home is consuming 1,200 real watts, and 1,250
apparent watts.  This results in a power factor of 1200/1250, which equals
0.96.  Pretty darn good.

Next, your grid-tie inverter provides 1,000 real watts back to the utility 
company,
which in turn is 1,000 real watts that the utility company no longer needs to
provide to the load described above.  Thus the net "real" power consumed as
seen by the utility is now 1,200W - 1,000W = 200W.

This means they sell only 200 watts to power your load, but the "apparent"
power aspect is still there.

End result?

200 real watts / 1250 apparent watts yields a power factor of 0.160.  Terrible 
by
any power company standards, yet you've removed 1,000 watts from the grid.
This is the value that will be displayed on your  meter.

Efforts are underway by EPRI and others to help create standards for future
generations of grid-tied inverters capable of generating "reactive" power (where
volts and amps are out of phase with each other) to help mitigate this effect.
I'm a member of the committee working toward that goal.  (No, we're not there
yet. It'll take time.)

This is a very difficult topic to discuss and explain.  Hopefully this helped.

Like Tom Cruise said at the end of "Top Gun" .. "It's complicated."


Dan



--- On Mon, 5/7/12, toddc...@finestplanet.com  wrote:


>From: toddc...@finestplanet.com 
>Subject: [RE-wrenches] power factor
>To: "RE-wrenches" 
>Date: Monday, May 7, 2012,  9:46 PM
>
>
>wrenches, 
>
>> 
>i have a question about my home's system. i was one of the first net metered 
>systems in our area, so the utility company installed a fancy dual register 
>meter which also displays kvar/power factor. 
>
>> 
>when selling 1 kW today the power factor was .40 and the kvar was 2.37. 
>
>> 
>this sounds horrible. question: is this a concern? 
>
>> 
>todd 
>
>> 
>
>>Sent from Finest Planet WebMail. 
>-Inline Attachment Follows-
>
>
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Re: [RE-wrenches] power factor

[toddcory]

excellent replies to yes, a complicated issue. i think i finally understand 
this. thank you kent and dan!
 
todd
 
 
 
On Monday, May 7, 2012 9:02pm, "Exeltech"  said:




Hello Todd,

The short answer to your "is this a concern?" query, is "no".

Reactive power is one of the more complex aspects of electric power, and
certainly one of the most misunderstood.  It can and does involve inductive
loads (e.g. motors), capacitive loads (e.g. some types of power supplies),
and non-linear loads (e.g. switch-mode power supplies, dimmers, etc.).

You likely know (or should know) "power factor" is the ratio of real power to
reactive power consumed by a load.  Grid-tie inverters generate "real" watts,
which are then coupled to the grid.  When a reactive load in your home is
consuming power, and you provide real watts to the load from the inverter,
this changes the ratio of real to apparent power consumed by the load as
seen by the utility company.

Dividing real power by  apparent power results in a unit-less value between 0
and 1 that describes this ratio.

Let's say a load in your home is consuming 1,200 real watts, and 1,250
apparent watts.  This results in a power factor of 1200/1250, which equals
0.96.  Pretty darn good.

Next, your grid-tie inverter provides 1,000 real watts back to the utility 
company,
which in turn is 1,000 real watts that the utility company no longer needs to
provide to the load described above.  Thus the net "real" power consumed as
seen by the utility is now 1,200W - 1,000W = 200W.

This means they sell only 200 watts to power your load, but the "apparent"
power aspect is still there.

End result?

200 real watts / 1250 apparent watts yields a power factor of 0.160.  Terrible 
by
any power company standards, yet you've removed 1,000 watts from the grid.
This is the value that will be displayed on your  meter.

Efforts are underway by EPRI and others to help create standards for future
generations of grid-tied inverters capable of generating "reactive" power (where
volts and amps are out of phase with each other) to help mitigate this effect.
I'm a member of the committee working toward that goal.  (No, we're not there
yet. It'll take time.)

This is a very difficult topic to discuss and explain.  Hopefully this helped.

Like Tom Cruise said at the end of "Top Gun" .. "It's complicated."


Dan



--- On Mon, 5/7/12, toddc...@finestplanet.com  wrote:

From: toddc...@finestplanet.com 
Subject: [RE-wrenches] power factor
To: "RE-wrenches" 
Date: Monday, May 7, 2012,  9:46 PM





wrenches,
i have a question about my home's system. i was one of the first net metered 
systems in our area, so the utility company installed a fancy dual register 
meter which also displays kvar/power factor.
when selling 1 kW today the power factor was .40 and the kvar was 2.37.
this sounds horrible. question: is this a concern?
todd




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Re: [RE-wrenches] power factor

[Exeltech]

Hello Todd,

The short answer to your "is this a concern?" query, is "no".

Reactive power is one of the more complex aspects of electric power, and
certainly one of the most misunderstood.  It can and does involve inductive
loads (e.g. motors), capacitive loads (e.g. some types of power supplies),
and non-linear loads (e.g. switch-mode power supplies, dimmers, etc.).

You likely know (or should know) "power factor" is the ratio of real power to
reactive power consumed by a load.  Grid-tie inverters generate "real" watts,
which are then coupled to the grid.  When a reactive load in your home is
consuming power, and you provide real watts to the load from the inverter,
this changes the ratio of real to apparent power consumed by the load as
seen by the utility company.

Dividing real power by apparent power results in a unit-less value between 0
and 1 that describes this ratio.

Let's say a load in your home is consuming 1,200 real watts, and 1,250
apparent watts.  This results in a power factor of 1200/1250, which equals
0.96.  Pretty darn good.

Next, your grid-tie inverter provides 1,000 real watts back to the utility 
company,
which in turn is 1,000 real watts that the utility company no longer needs to
provide to the load described above.  Thus the net "real" power consumed as
seen by the utility is now 1,200W - 1,000W = 200W.

This means they sell only 200 watts to power your load, but the "apparent"
power aspect is still there.

End result?

200 real watts / 1250 apparent watts yields a power factor of 0.160.  Terrible 
by
any power company standards, yet you've removed 1,000 watts from the grid.
This is the value that will be displayed on your meter.

Efforts are underway by EPRI and others to help create standards for future
generations of grid-tied inverters capable of generating "reactive" power (where
volts and amps are out of phase with each other) to help mitigate this effect.
I'm a member of the committee working toward that goal.  (No, we're not there
yet. It'll take time.)

This is a very difficult topic to discuss and explain.  Hopefully this helped.

Like Tom Cruise said at the end of "Top Gun" .. "It's complicated."


Dan



--- On Mon, 5/7/12, toddc...@finestplanet.com  wrote:

From: toddc...@finestplanet.com 
Subject: [RE-wrenches] power factor
To: "RE-wrenches" 
Date: Monday, May 7, 2012, 9:46 PM




wrenches,


i have a question about my home's system. i was one of the first net metered 
systems in our area, so the utility company installed a fancy dual register 
meter which also displays kvar/power factor.


when selling 1 kW today the power factor was .40 and the kvar was 2.37.


this sounds horrible. question: is this a concern?


todd









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Re: [RE-wrenches] Power Factor (was Efficient step up, down transformers)

[Joel Davidson]

Hi Bob,
The inverter PF was 1.0. The grid was always less than 1.0 and often down to 
0.7. LADWP would not say what they did to fix the problem.

Joel Davidson

- Original Message - 
From: "boB Gudgel" 

To: "RE-wrenches" 
Cc: "Joel Davidson" 
Sent: Tuesday, July 26, 2011 7:30 PM
Subject: Re: [RE-wrenches] Power Factor (was Efficient step up, down 
transformers)




On 7/26/2011 4:42 PM, Joel Davidson wrote:
Power factor less than 1.0 can shorten the life of and damage equipment 
and reduce PV production. We installed a 200 kW PV system on a facility 
with a lot of 3-phase motors and monitored the PV and the grid. We 
measured around 0.7 PF being delivered by the Los Angeles Dept of Water & 
Power. The data was used as evidence by the PV client to negotiate 
compensation for lost power and get better quality power at that site and 
other facilities. Now I always monitor utility power on commercial 
systems for trouble-shooting.


Joel Davidson




That's very interesting...   I would expect   a current-source type grid 
tie inverter would
be very close to PF of 1.0 (if that one WAS a CS type which I would think 
it would be)


Might be because the grid voltage at that facility is really distorted 
because of the loads
you mentioned.  Did you measure the PF of the line from the GT inverter 
itself ?


What kind of inverter system was this ??   A big one of course.

Some GT inverters that are more of a voltage source will supply lower 
power factor

and tend to clean up the dirty voltage waveform.

boB







- Original Message - From: "Exeltech" 
To: "RE-wrenches" 
Sent: Tuesday, July 26, 2011 12:13 PM
Subject: Re: [RE-wrenches] Efficient step up, down transformers


Hello Ray,

Wow.  I could do an another thesis on the topic of
power factor alone...

There's no good way to fully explain this in depth
here .. so all we can do is scratch the surface.


First, a quick review.

Power factor less than 1.0 causes current flow in a load
that's out of phase with the applied voltage.  The actual
power delivered to the load (and thus consumed by the
source, disregarding efficiency for now), would be:
Vac * Iac * COS(theta) .. where theta is the phase angle
differential between the voltage and current (with the
values for V and I in rms).

Though the real power consumed in a reactive circuit
is going to be less than the real power consumed in
an equivalent resistive circuit (by virtue of the
phase angle), the amperage in the reactive circuit
is still whatever is flowing.

Now, to answer your question...

All inverters will operate at a lower efficiency
when connected to a load with lousy power factor
than if connected to a purely resistive load
under similar operating conditions (VA vs. watts).

The actual efficiency reduction will depend also
on whether the low power factor is due to reactive
components (e.g. inductors or capacitors), or
due to a non-linear load, such as a switching power
supply in a computer, microwave oven, etc.

Nonlinear loads present their own issues that I'll
skip for now.  Let's presume reactive...


That said...

The majority of the losses in inverters under
these conditions would be resistive.


Here's why:
Inverters made with power transformers have large
amounts of copper wire, and consequently, wire
resistance.  When connected to a load with a poor
power factor, transformer-based inverters will not
perform as efficiently as they do when connected
to a purely resistive load.

With a very low power-factor load, you could
theoretically be providing the max current from
an inverter at much lower real power output than
it's rated.  This additional loss, when taken
into account at an AC power with low real wattage
output, will make the inverter's efficiency
worse than with a resistive load.  Expect the
efficiency hit to be on the order of 2-5% for
transformer-based inverters (again, depending on
inverter's max wattage rating as well, as this
will impact the wire size used in its construction,
and thus the total wire resistance).

Transformerless inverters don't have this large
mass of wire (thus much lower internal resistance).
Subsequently, they aren't nearly as affected by
low-power-factor loads - but even here, I'd expect
around 0.5-1% efficiency reduction, all other
conditions being equal.


Power factor is deceptively simple .. but is one of
the more complex aspects of power systems and
power equipment design.


Hope this helps.


Dan Lepinski
Sr. Engineer
Exeltech


P.S. Thanks for being a long-time Exeltech customer.
Much appreciated.



--- On Mon, 7/25/11, R Ray Walters  wrote:

From: R Ray Walters 
Subject: Re: [RE-wrenches] Efficient step up, down transformers
To: "RE-wrenches" 
Date: Monday, July 25, 2011, 4:10 PM
Hi Dan;

I agree that a 2000 VA inverter isn't equal to a 2000 watt
unit.

The focus on VA here though was not about looking 

Re: [RE-wrenches] Power Factor (was Efficient step up, down transformers)

[boB Gudgel]

On 7/26/2011 4:42 PM, Joel Davidson wrote:
Power factor less than 1.0 can shorten the life of and damage 
equipment and reduce PV production. We installed a 200 kW PV system on 
a facility with a lot of 3-phase motors and monitored the PV and the 
grid. We measured around 0.7 PF being delivered by the Los Angeles 
Dept of Water & Power. The data was used as evidence by the PV client 
to negotiate compensation for lost power and get better quality power 
at that site and other facilities. Now I always monitor utility power 
on commercial systems for trouble-shooting.


Joel Davidson




That's very interesting...   I would expect   a current-source type grid 
tie inverter would
be very close to PF of 1.0 (if that one WAS a CS type which I would 
think it would be)


Might be because the grid voltage at that facility is really distorted 
because of the loads
you mentioned.  Did you measure the PF of the line from the GT inverter 
itself ?


What kind of inverter system was this ??   A big one of course.

Some GT inverters that are more of a voltage source will supply lower 
power factor

and tend to clean up the dirty voltage waveform.

boB







- Original Message - From: "Exeltech" 
To: "RE-wrenches" 
Sent: Tuesday, July 26, 2011 12:13 PM
Subject: Re: [RE-wrenches] Efficient step up, down transformers


Hello Ray,

Wow.  I could do an another thesis on the topic of
power factor alone...

There's no good way to fully explain this in depth
here .. so all we can do is scratch the surface.


First, a quick review.

Power factor less than 1.0 causes current flow in a load
that's out of phase with the applied voltage.  The actual
power delivered to the load (and thus consumed by the
source, disregarding efficiency for now), would be:
Vac * Iac * COS(theta) .. where theta is the phase angle
differential between the voltage and current (with the
values for V and I in rms).

Though the real power consumed in a reactive circuit
is going to be less than the real power consumed in
an equivalent resistive circuit (by virtue of the
phase angle), the amperage in the reactive circuit
is still whatever is flowing.

Now, to answer your question...

All inverters will operate at a lower efficiency
when connected to a load with lousy power factor
than if connected to a purely resistive load
under similar operating conditions (VA vs. watts).

The actual efficiency reduction will depend also
on whether the low power factor is due to reactive
components (e.g. inductors or capacitors), or
due to a non-linear load, such as a switching power
supply in a computer, microwave oven, etc.

Nonlinear loads present their own issues that I'll
skip for now.  Let's presume reactive...


That said...

The majority of the losses in inverters under
these conditions would be resistive.


Here's why:
Inverters made with power transformers have large
amounts of copper wire, and consequently, wire
resistance.  When connected to a load with a poor
power factor, transformer-based inverters will not
perform as efficiently as they do when connected
to a purely resistive load.

With a very low power-factor load, you could
theoretically be providing the max current from
an inverter at much lower real power output than
it's rated.  This additional loss, when taken
into account at an AC power with low real wattage
output, will make the inverter's efficiency
worse than with a resistive load.  Expect the
efficiency hit to be on the order of 2-5% for
transformer-based inverters (again, depending on
inverter's max wattage rating as well, as this
will impact the wire size used in its construction,
and thus the total wire resistance).

Transformerless inverters don't have this large
mass of wire (thus much lower internal resistance).
Subsequently, they aren't nearly as affected by
low-power-factor loads - but even here, I'd expect
around 0.5-1% efficiency reduction, all other
conditions being equal.


Power factor is deceptively simple .. but is one of
the more complex aspects of power systems and
power equipment design.


Hope this helps.


Dan Lepinski
Sr. Engineer
Exeltech


P.S. Thanks for being a long-time Exeltech customer.
Much appreciated.



--- On Mon, 7/25/11, R Ray Walters  wrote:

From: R Ray Walters 
Subject: Re: [RE-wrenches] Efficient step up, down transformers
To: "RE-wrenches" 
Date: Monday, July 25, 2011, 4:10 PM
Hi Dan;

I agree that a 2000 VA inverter isn't equal to a 2000 watt
unit.

The focus on VA here though was not about looking at the
rating of the inverter, but instead noting that a load with
a high reactive component might draw more energy than a
purely resistive load in a battery based inverter system. AC
watts might be equal, but my understanding (perhaps false?)
is that the inverter efficiency decreases with PF.

SInce you're in the inverter manufacturing biz, perhaps you
could better explain this to the rest of us.

My fundamental question is: how does power factor effect
the efficiency of an inverter?

A better underst

Re: [RE-wrenches] Power Factor and Grid Tied PV

[boB Gudgel]

swingjun...@gmail.com wrote:

Thanks to all who responded,

The article Marco references, is the one referenced in the tinyurl in 
my original post. I did not find anything of significance in the 
previous Solar Pro issues. Based on the responses it seems there is no 
good data out there to answer the question posted. This may be due to


1) the fact that PV systems are not being installed in commercial 
facilities with large reactive loads
2) those facilities are not penalized for PF therefor the question is 
irrelevant to those system owners
3) the PV systems installed in such facilities are small with respect 
to the overall facilities load and any negative impact on PF is 
insignificant


Cheers
Carl
  


I don't think there is anything to be concerned about if the PF goes 
down because a grid tie inverter is helping
to support the real power loads.  The I-squared-R losses won't get any 
larger for the utility.  I think it's just
because the Numerator of   Watts / VAR goes down, and the denominator 
staying the same that is

making the measure Power Factor measurement go down.

Also, I believe that this is only for "current source" inverters, which 
accounts for most GT inverters today...
An older SW inverter,  say, (voltage source) would actually supply VARs 
to the system and probably

wouldn't change the measured PF to the utility very much, if at all.

My 2 cents for today.
boB











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Re: [RE-wrenches] Power Factor and Grid Tied PV

[swingjunkie]

Thanks to all who responded,

The article Marco references, is the one referenced in the tinyurl in my  
original post. I did not find anything of significance in the previous  
Solar Pro issues. Based on the responses it seems there is no good data out  
there to answer the question posted. This may be due to


1) the fact that PV systems are not being installed in commercial  
facilities with large reactive loads
2) those facilities are not penalized for PF therefor the question is  
irrelevant to those system owners
3) the PV systems installed in such facilities are small with respect to  
the overall facilities load and any negative impact on PF is insignificant


Cheers
Carl
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Re: [RE-wrenches] Power Factor and Grid Tied PV

[Kent Osterberg]

Marco,

Three components of power delivered by the utility company: Watts,
volt-amps-reactive (VAR), and apparent power or volt-amps (VA).  Power
factor is the ratio of the watts to the volt-amps.  PF = Watts/VA.

To see how this works: draw a right triangle with 8 kW as the
horizontal leg, 6 kVAR  as the vertical leg, and 10 kVA as the
hypotenuse.  The power factor is 8 kW/10 kVA = 0.8.   Now put in a 4-kW
solar system.  The 6 kVAR reactive load doesn't change  So the solar
system reduces the real power delivered by the utility by 50%, the
reactive power by 0%, and the apparent power by 28%.  The power factor
afterwards is PF = 4 kW/7.21 kVA = 0.55.  The power factor did get
worse!   To see how that all works just draw a new hypotenuse starting
from the midpoint of the 8-kW horizontal leg.  Hardly seems worthy of a
paper.  But the utility doesn't like to supply power for a load with a
power factor less than 0.8 because the out of phase current still
causes I-squared x R losses or line losses.  


Joel,

The utility company isn't responsible for the power factor.  The
customers' loads determine the power used and the power factor.  The
utility company is responsible for the power quality, which is really
poor in lots of locations.

Kent Osterberg
Blue Mountain Solar, Inc.



Marco Mangelsdorf wrote:

  According to an article, written by a utility engineer on O'ahu, PF can be
worsened at the site where a substantial PV system is located.

If there is a poor or wavering PF due to an abundance of inductive loads at
a particular site, having a large inverter, in relation to the overall power
consumption of the facility, can actually make the PF worse.

I can track down that piece for anyone interested.

Marco
ProVision Solar

-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Joel
Davidson
Sent: Thursday, January 07, 2010 5:42 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Power Factor and Grid Tied PV

We worked on dozens of commercial PV systems in Southern California Edison 
(SCE), Los Angeles Department of Water & Power (LADWP), and San Diego Gas & 
Electric (SDG&E) territories. We installed Xantrex, SMA, and SatCon 
inverters and measured power factor on both the grid and the inverters. In 
every case, inverter power factor was 1. In almost every case LADWP's power 
factor was less than 1 and in older parts of Los Angeles power factor was 
often 0.75. SCE and SDG&E generally has pretty good power factors. In 
general, PV inverters do not worsen grid power factor. In general, newer 
sections of the grid are better designed and better managed than older grid 
sections. When utility companies or anyone says PV causes grid problems, ask

for proof.
Joel Davidson

- Original Message - 
From: "Darryl Thayer" 
To: "RE-wrenches" 
Sent: Wednesday, January 06, 2010 9:39 PM
Subject: Re: [RE-wrenches] Power Factor and Grid Tied PV


I recently spoke with an inverter manufacture and I left with the following 
opinion.  Normally the inverter takes the unity power factor load and leaves

the reactive load.  making the power factor worse.  However the power factor

could be corrected by the inverter, However this would add cost to the 
inverter and would not appear to have value to the solar industry.  There 
are variable reactance devices existing that can correct power factor, is 
there need for another device?

Darryl


  
  
Hello Wrenches,

Commercial power customers often are penalized for low
power factors.
Looking for other info I came across this article, which
seems to
cover the subject from an academic standpoint.
http://tinyurl.com/ye5pzrw Does anyone
have real world data which
might shed light on the impact of a DGT PV system on power
factor.

With Regards
Carl Adams
SunRock Solar, LLC.
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Re: [RE-wrenches] Power Factor and Grid Tied PV

[Joel Davidson]

We worked on dozens of commercial PV systems in Southern California Edison 
(SCE), Los Angeles Department of Water & Power (LADWP), and San Diego Gas & 
Electric (SDG&E) territories. We installed Xantrex, SMA, and SatCon 
inverters and measured power factor on both the grid and the inverters. In 
every case, inverter power factor was 1. In almost every case LADWP's power 
factor was less than 1 and in older parts of Los Angeles power factor was 
often 0.75. SCE and SDG&E generally has pretty good power factors. In 
general, PV inverters do not worsen grid power factor. In general, newer 
sections of the grid are better designed and better managed than older grid 
sections. When utility companies or anyone says PV causes grid problems, ask 
for proof.

Joel Davidson

- Original Message - 
From: "Darryl Thayer" 

To: "RE-wrenches" 
Sent: Wednesday, January 06, 2010 9:39 PM
Subject: Re: [RE-wrenches] Power Factor and Grid Tied PV


I recently spoke with an inverter manufacture and I left with the following 
opinion.  Normally the inverter takes the unity power factor load and leaves 
the reactive load.  making the power factor worse.  However the power factor 
could be corrected by the inverter, However this would add cost to the 
inverter and would not appear to have value to the solar industry.  There 
are variable reactance devices existing that can correct power factor, is 
there need for another device?


Darryl



Hello Wrenches,

Commercial power customers often are penalized for low
power factors.
Looking for other info I came across this article, which
seems to
cover the subject from an academic standpoint.
http://tinyurl.com/ye5pzrw Does anyone
have real world data which
might shed light on the impact of a DGT PV system on power
factor.

With Regards
Carl Adams
SunRock Solar, LLC.
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Re: [RE-wrenches] Power Factor and Grid Tied PV

[Kent Osterberg]

Darryl,

The inverter is reducing the real power used by the customer but not
the reactive power.   So it does make the power factor worse when you
are looking at from the utility meter.  Since most customers don't pay
for reactive power it doesn't matter to them.  But some customers do
pay for reactive power and the solar system doesn't help on the
reactive side of the bill.  Variable reactor devices are made to
improve power factor by providing leading or lagging reactive power. 
The solar powered inverter doesn't reduce or increase the need for a
variable reactive device.  If you are dealing with an industrial
customer that is billed for reactive power, or VAR-hrs, it is important
to make sure they are aware that the solar system won't help with that
portion of the bill.

>From the utility's perspective the fact that the solar inverter only
provides real power is bad, except when they are billing customers for
reactive power.  Take a look at a "Net Zero" possibility for the
house.  The kWhs used is net zero, but reactive power was still
provided by the utility company: a service they weren't paid for yet
did have an impact on equipment in their system.  When solar starts
having a 5%, 10%, 15% impact on the total residential load, you'll see
the utilities screaming for tariffs that allow them to bill residential
customers (or at least grid interactive customers) for reactive power,
or for higher monthly base fees.  The greedy-guts will probably ask for
both and an allowance for lost kWh sales too.

Kent Osterberg
Blue Mountain Solar, Inc.



Darryl Thayer wrote:

  I recently spoke with an inverter manufacture and I left with the following opinion.  Normally the inverter takes the unity power factor load and leaves the reactive load.  making the power factor worse.  However the power factor could be corrected by the inverter, However this would add cost to the inverter and would not appear to have value to the solar industry.  There are variable reactance devices existing that can correct power factor, is there need for another device?  

Darryl  

 
  
  
Hello Wrenches,

Commercial power customers often are penalized for low
power factors.
Looking for other info I came across this article, which
seems to
cover the subject from an academic standpoint.
http://tinyurl.com/ye5pzrw    Does anyone
have real world data which
might shed light on the impact of a DGT PV system on power
factor.

With Regards
Carl Adams
SunRock Solar, LLC.
___

  
  


  
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Re: [RE-wrenches] Power Factor and Grid Tied PV

[Darryl Thayer]

I recently spoke with an inverter manufacture and I left with the following 
opinion.  Normally the inverter takes the unity power factor load and leaves 
the reactive load.  making the power factor worse.  However the power factor 
could be corrected by the inverter, However this would add cost to the inverter 
and would not appear to have value to the solar industry.  There are variable 
reactance devices existing that can correct power factor, is there need for 
another device?  

Darryl  

 
> Hello Wrenches,
> 
> Commercial power customers often are penalized for low
> power factors.
> Looking for other info I came across this article, which
> seems to
> cover the subject from an academic standpoint.
> http://tinyurl.com/ye5pzrw    Does anyone
> have real world data which
> might shed light on the impact of a DGT PV system on power
> factor.
> 
> With Regards
> Carl Adams
> SunRock Solar, LLC.
> ___



  
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Re: [RE-wrenches] Power Factor and Grid Tied PV

[wratterman]

I think one of the recent Solar Pro web articles discussed the unity power 
factor production of the dgt systems and their affect on the overall p.f.

Thanks

Walt
SunEPI
--Original Message--
From: Carl Adams
Sender: re-wrenches-boun...@lists.re-wrenches.org
To: RE-wrenches@lists.re-wrenches.org
ReplyTo: RE-wrenches
Subject: [RE-wrenches] Power Factor and Grid Tied PV
Sent: Jan 6, 2010 11:49 AM

Hello Wrenches,

Commercial power customers often are penalized for low power factors.
Looking for other info I came across this article, which seems to
cover the subject from an academic standpoint.
http://tinyurl.com/ye5pzrwDoes anyone have real world data which
might shed light on the impact of a DGT PV system on power factor.

With Regards
Carl Adams
SunRock Solar, LLC.
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Re: [RE-wrenches] power factor

[boB Gudgel]

Brian Teitelbaum wrote:

boB,

Not only does that make sense, it's the best explanation of the effect of power 
factor on an off-grid system that I've read.

I would than assume that this means that Drake's refrigerator is actually consuming more 
power from his battery system than is just measured in AC watts at the fridge. Some 
energy is lost as heat in the inverter system while the fridge is running, at least more 
than would be if the fridge had a higher power factor. I would also assume that measuring 
the DC amperage in the battery cables, and subtracting the "normal" inverter 
losses, would give a more accurate reading of the Fridge's true running watts.

There are a number of plug-in products on the market that are supposed to 
improve power factor, apparently through added capacitance. How would they work 
here, or would they?
  

Great question and I'm not sure I have a good answer.

You would have to modify the refrigerator itself to make it have a 
higher power factor, and I would hope that the appliance manufacturer 
has designed it to work as
good as it can.  Are those high efficiency refrigerators power factor 
corrected though, since Europe requires power factor close to 1.0 and 
the good ones

are also used there ?

I've seen many discussions about those power factor correction units for 
home use, and I think the consensus is that they really don't help much, 
if at all

...Mainly because the homeowner only pays for real power.

I think that the higher the inverter efficiency, the better it will work 
with lower PF loads, because it has to keep its AC source impedance low when
powering that refrigerator (or whatever), because it has  to circulate 
and "slosh" around those reactive currents.


Lower resistance  =equals=  higher efficiency,  =equals=  better low 
power factor performance,  is one way to look at that.


Adding extra and opposite reactance  for power factor correction is 
something that utilities do at large reactive consumers such as steel 
mills.  It makes sense for that
type of power usage.   BTW, if the primary power factor is low because 
of big inductive loads, they add capacitors, and if capacitive, they add 
inductors to pull the power
factor  back towards 1.0.  At least that's the "passive" method that I'm 
familiar with for low Displacement Power Factor, (DPF).


But what happens if you have all that passive PF correction in place, 
and all of a sudden the load reduces or goes resistive ? Then you're left
with a nice low power factor load again.  (I think they take that into 
account and make it average out).


Then, there's active, electronic PFC.I probably won't be around to 
see, but I bet that high temperature

superconductors will play a big roll in reducing all losses.

boB


Brian Teitelbaum
AEE Solar



-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of boB Gudgel
Sent: Wednesday, August 19, 2009 9:28 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] power factor

Drake Chamberlin wrote:
  

One question about power factor:

We know it is the ratio of the real power to the apparent power, and
that most utility meters only register real power (watts).  Reactive
power doesn't dissipate as heat like power loss through a resistor.

The question is:  What is the quantitative effect that reactive power
has on a battery bank that is feeding loads through an inverter?  If
the power factor is 56% (like a refrigerator that I want to replace)
does that mean that only 56% of the power being drawn from the
batteries is being used to power the refrigerator?.  If so, where does
the rest of the power go?



If you just take your meter and multiply Volts X Amps, that's VA, or
apparent power.   If it's all real, then it's like the resistor and gets
counted by
the utility meter.  Some turns into heat (resistor) and some gets some
real work done.

The rest, is VA but is Reactive and is  VA Reactive or VARs.

So, the reactive current that comes out of the batteries, into the
inverter out the AC output, comes BACK into the battery.  (this is for
an inverter
that has the ripple reflecting back into the battery)

So, your batter kind of discharges and then recharges 120 times per
second for a 60 Hz system.
So, where does the power go ?   The real power gets used of course and
most of the rest, the VARs gets put back into
the battery.   HOWEVER, since the transformer and wire and FETs and
transormer and stuff have resistance, some of those VARS get turned
into heat by that inefficiency, or I-squared-R losses.  That's one
reason why low power factor isn't so good.

Does that kind of make sense ?

boB

  

Thanks,

Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648

--

Re: [RE-wrenches] power factor

[Brian Teitelbaum]

boB,

Not only does that make sense, it's the best explanation of the effect of power 
factor on an off-grid system that I've read.

I would than assume that this means that Drake's refrigerator is actually 
consuming more power from his battery system than is just measured in AC watts 
at the fridge. Some energy is lost as heat in the inverter system while the 
fridge is running, at least more than would be if the fridge had a higher power 
factor. I would also assume that measuring the DC amperage in the battery 
cables, and subtracting the "normal" inverter losses, would give a more 
accurate reading of the Fridge's true running watts.

There are a number of plug-in products on the market that are supposed to 
improve power factor, apparently through added capacitance. How would they work 
here, or would they?

Brian Teitelbaum
AEE Solar



-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of boB Gudgel
Sent: Wednesday, August 19, 2009 9:28 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] power factor

Drake Chamberlin wrote:
> One question about power factor:
>
> We know it is the ratio of the real power to the apparent power, and
> that most utility meters only register real power (watts).  Reactive
> power doesn't dissipate as heat like power loss through a resistor.
>
> The question is:  What is the quantitative effect that reactive power
> has on a battery bank that is feeding loads through an inverter?  If
> the power factor is 56% (like a refrigerator that I want to replace)
> does that mean that only 56% of the power being drawn from the
> batteries is being used to power the refrigerator?.  If so, where does
> the rest of the power go?

If you just take your meter and multiply Volts X Amps, that's VA, or
apparent power.   If it's all real, then it's like the resistor and gets
counted by
the utility meter.  Some turns into heat (resistor) and some gets some
real work done.

The rest, is VA but is Reactive and is  VA Reactive or VARs.

So, the reactive current that comes out of the batteries, into the
inverter out the AC output, comes BACK into the battery.  (this is for
an inverter
that has the ripple reflecting back into the battery)

So, your batter kind of discharges and then recharges 120 times per
second for a 60 Hz system.
So, where does the power go ?   The real power gets used of course and
most of the rest, the VARs gets put back into
the battery.   HOWEVER, since the transformer and wire and FETs and
transormer and stuff have resistance, some of those VARS get turned
into heat by that inefficiency, or I-squared-R losses.  That's one
reason why low power factor isn't so good.

Does that kind of make sense ?

boB

>
> Thanks,
>
> Drake Chamberlin
> Athens Electric
> OH License 44810
> CO License 3773
> NABCEP TM  Certified PV Installer
> Office - 740-448-7328
> Mobile - 740-856-9648
>
> 
>
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Re: [RE-wrenches] power factor

[boB Gudgel]

Drake Chamberlin wrote:

One question about power factor:

We know it is the ratio of the real power to the apparent power, and 
that most utility meters only register real power (watts).  Reactive 
power doesn't dissipate as heat like power loss through a resistor. 

The question is:  What is the quantitative effect that reactive power 
has on a battery bank that is feeding loads through an inverter?  If 
the power factor is 56% (like a refrigerator that I want to replace) 
does that mean that only 56% of the power being drawn from the 
batteries is being used to power the refrigerator?.  If so, where does 
the rest of the power go? 


If you just take your meter and multiply Volts X Amps, that's VA, or 
apparent power.   If it's all real, then it's like the resistor and gets 
counted by
the utility meter.  Some turns into heat (resistor) and some gets some 
real work done.


The rest, is VA but is Reactive and is  VA Reactive or VARs.

So, the reactive current that comes out of the batteries, into the 
inverter out the AC output, comes BACK into the battery.  (this is for 
an inverter

that has the ripple reflecting back into the battery)

So, your batter kind of discharges and then recharges 120 times per 
second for a 60 Hz system.
So, where does the power go ?   The real power gets used of course and 
most of the rest, the VARs gets put back into
the battery.   HOWEVER, since the transformer and wire and FETs and 
transormer and stuff have resistance, some of those VARS get turned
into heat by that inefficiency, or I-squared-R losses.  That's one 
reason why low power factor isn't so good.


Does that kind of make sense ?

boB



Thanks,

Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648



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Re: [RE-wrenches] power factor

[Drake Chamberlin]

One question about power factor:

We know it is the ratio of the real power to the apparent power, and 
that most utility meters only register real power (watts).  Reactive 
power doesn't dissipate as heat like power loss through a resistor.


The question is:  What is the quantitative effect that reactive power 
has on a battery bank that is feeding loads through an inverter?  If 
the power factor is 56% (like a refrigerator that I want to replace) 
does that mean that only 56% of the power being drawn from the 
batteries is being used to power the refrigerator?.  If so, where 
does the rest of the power go?


Thanks,

Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648  ___
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Re: [RE-wrenches] power factor

[Exeltech]

Robert,

Exeltech purchased two cartons of the Kill-A-Watt meters to use for relative 
power tests (pacing off the room for area sort of thing).  We found them to be 
accurate within 2-3% when compared to our multi-thousand  dollar power meters 
that we  calibrate to NIST standards every year. We've not done exhaustive 
comparisons .. but for the price, we do find them acceptable.

Dan




--- On Wed, 8/12/09, robert ellison  wrote:

From: robert ellison 
Subject: Re: [RE-wrenches] power factor
To: "RE-wrenches" 
Date: Wednesday, August 12, 2009, 8:59 AM

I have used the Brand power meter until someone absconded with it. I  
understood that the original "Kill a watt" meter was real inaccurate. So i have 
stayed away from it.
Might that have changed?
 
Bob 


On Tue, Aug 11, 2009 at 12:35 PM, jay peltz  wrote:

HI All,

For plug in watts/PF meters is there a better or more accurate one that anyone 
recommends?


I've tried the Kill-a-watt and seems to work and be pretty accurate, but 
haven't compared it to many others.

I've been testing some CFLS vs LED and the PF is way better on the LED.
For us off grid folks its pretty interesting.


thanks,

jay



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Re: [RE-wrenches] power factor

[robert ellison]

I have used the Brand power meter until someone absconded with it. I
 understood that the original "Kill a watt" meter was real inaccurate. So i
have stayed away from it.
Might that have changed?

Bob

On Tue, Aug 11, 2009 at 12:35 PM, jay peltz  wrote:

> HI All,
>
> For plug in watts/PF meters is there a better or more accurate one that
> anyone recommends?
>
> I've tried the Kill-a-watt and seems to work and be pretty accurate, but
> haven't compared it to many others.
>
> I've been testing some CFLS vs LED and the PF is way better on the LED.
> For us off grid folks its pretty interesting.
>
> thanks,
>
> jay
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Re: [RE-wrenches] Power Factor

[Matt Tritt]

I took boB's advice and talked to Magnum about the problem. Their take 
on it? "Hmmm, beats me!" I might be paraphrasing, but that's the drift. 
All in all, I'd say that the suggestions from the group are at least as 
good as the one's from the manufacturer.


Matt T

Larry Crutcher, Starlight Solar wrote:

Don't forget, this is a Magnum inverter and Magnum has issues. I have  
two customers with Magnum problems. One is a washer that will work  
perfectly on a cheap import inverter; the other has a Vizio TV that  
works fine on shore power and generator. S...maybe there are 
pumps  and other items that are anti-Magnum.



Larry Crutcher
Starlight Solar
(928) 941-1660
Renewable Energy Products, Service and Installation


On Aug 1, 2009, at 12:24 PM, boB Gudgel wrote:


Chris Worcester wrote:


Has he checked the torque on all the battery connections?

Sincerely,

Chris Worcester
Solar Wind Works
NABCEP Certified PV Installer
Phone: 530-582-4503
Fax: 530-582-4603
www.solarwindworks.com
ch...@solarwindworks.com
"Proven Energy Solutions"




Also, Evidence of a bad battery connection (or bad inverter) should  
be obvious if the house lights dim

when the pump tries to start.

boB








-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Matt
Sent: Thursday, July 30, 2009 3:25 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Power Factor

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with  
a Magna
AE 48. Or rather, he isn't. According to him when he first fired it  
up, it
operated the pump just fine. The next time he tried, though. he  
couldn't

even get a buzz out of the starter. No workee.

The inverter runs all the other loads in the house fine, just not  
the pump.

He can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think  
not), a

motor starter problem or an inverter issue? I have to admit to being
somewhat baffled by this one because it ran the pump once, but not  
after.


Matt T


 boB Gudgel  wrote:


boB Gudgel wrote:

>>So, because of the different ways of specifying PF, it is always  
best to think of Power Factor as being the ratio of real (in  
phase) power, or VA to reactive power >>(VARS or "Volt Ampere  
Reactive").   That will work in all cases.



OOOps !   See, this can get confusing.   Reverse what I just said   
Power Factor... " Definition: The ratio of true power to apparent  
power"  as David Brearley had just posted.  Otherwise, that  
calculation can give you an answer that is GREATER than 1.0 and  
you don't want that !


Had to eat some of my words.  I just wanted to point out that the  
phase shift method was called DPF.   Didn't Ian Woodenden do an  
article on PF
recently too ?  If not, he or someone probably should in one of  
the two HP magazines.


boB



R. Walters wrote:

Power factor expresses the time difference  between voltage peak  
and current peak on each of their sine waves. If both current  
and voltage waves are "in time", (their wave peaks match up)  
power factor is 1. If one is ahead or behind the other, it's  
not. Think about an electric motor: we hit it with a voltage  
wave, and a fraction of a second later, it actually moves, and  
the current wave happens. There is a little lag there. Resistive  
loads like lights have very little lag, and big electric motors  
coming up to speed can have horrible PF.


This definition of power factor only applies for linear loads  
with only inductance or capacitance (with resistance) and is  
called "Displacement Power Factor (DPF) and you will  see that on  
some power meters.


For non-linear loads, like battery chargers or computer power  
supplies without PF Correction,  the current waveform (on an O- 
scope) looks nothing like a sine or cosine wave.   The current  
"spikes up" at the AC voltage peaks.  It actually *looks like* it  
might be in phase, BUT the current and the voltage do NOT look  
the same.  It's non-linear.  Lower than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a  
PF of 1.0,  the current and voltage waveform will both look  
exactly the same AND there will be no phase shift.   They are  
both linear and all current and voltage is in phase at every  
point in the AC cycle.


So, because of the different ways of specifying PF, it is always  
best to think of Power Factor as being the ratio of real (in  
phase) power, or VA to reactive power (VARS or "Volt Ampere  
Reactive").   That will work in all cases. (Real Vs. Apparent  
power is the same thing).   Apparent power is what you get when  
you multiply
your RMS meter's Voltage by the RMS current and is calle

Re: [RE-wrenches] Power Factor

[Larry Crutcher, Starlight Solar]

Don't forget, this is a Magnum inverter and Magnum has issues. I have  
two customers with Magnum problems. One is a washer that will work  
perfectly on a cheap import inverter; the other has a Vizio TV that  
works fine on shore power and generator. S...maybe there are pumps  
and other items that are anti-Magnum.



Larry Crutcher
Starlight Solar
(928) 941-1660
Renewable Energy Products, Service and Installation


On Aug 1, 2009, at 12:24 PM, boB Gudgel wrote:


Chris Worcester wrote:

Has he checked the torque on all the battery connections?

Sincerely,

Chris Worcester
Solar Wind Works
NABCEP Certified PV Installer
Phone: 530-582-4503
Fax: 530-582-4603
www.solarwindworks.com
ch...@solarwindworks.com
"Proven Energy Solutions"




Also, Evidence of a bad battery connection (or bad inverter) should  
be obvious if the house lights dim

when the pump tries to start.

boB








-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Matt
Sent: Thursday, July 30, 2009 3:25 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Power Factor

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with  
a Magna
AE 48. Or rather, he isn't. According to him when he first fired it  
up, it
operated the pump just fine. The next time he tried, though. he  
couldn't

even get a buzz out of the starter. No workee.

The inverter runs all the other loads in the house fine, just not  
the pump.

He can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think  
not), a

motor starter problem or an inverter issue? I have to admit to being
somewhat baffled by this one because it ran the pump once, but not  
after.


Matt T


 boB Gudgel  wrote:

boB Gudgel wrote:

>>So, because of the different ways of specifying PF, it is always  
best to think of Power Factor as being the ratio of real (in  
phase) power, or VA to reactive power >>(VARS or "Volt Ampere  
Reactive").   That will work in all cases.



OOOps !   See, this can get confusing.   Reverse what I just said   
Power Factor... " Definition: The ratio of true power to apparent  
power"  as David Brearley had just posted.  Otherwise, that  
calculation can give you an answer that is GREATER than 1.0 and  
you don't want that !


Had to eat some of my words.  I just wanted to point out that the  
phase shift method was called DPF.   Didn't Ian Woodenden do an  
article on PF
recently too ?  If not, he or someone probably should in one of  
the two HP magazines.


boB



R. Walters wrote:

Power factor expresses the time difference  between voltage peak  
and current peak on each of their sine waves. If both current  
and voltage waves are "in time", (their wave peaks match up)  
power factor is 1. If one is ahead or behind the other, it's  
not. Think about an electric motor: we hit it with a voltage  
wave, and a fraction of a second later, it actually moves, and  
the current wave happens. There is a little lag there. Resistive  
loads like lights have very little lag, and big electric motors  
coming up to speed can have horrible PF.


This definition of power factor only applies for linear loads  
with only inductance or capacitance (with resistance) and is  
called "Displacement Power Factor (DPF) and you will  see that on  
some power meters.


For non-linear loads, like battery chargers or computer power  
supplies without PF Correction,  the current waveform (on an O- 
scope) looks nothing like a sine or cosine wave.   The current  
"spikes up" at the AC voltage peaks.  It actually *looks like* it  
might be in phase, BUT the current and the voltage do NOT look  
the same.  It's non-linear.  Lower than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a  
PF of 1.0,  the current and voltage waveform will both look  
exactly the same AND there will be no phase shift.   They are  
both linear and all current and voltage is in phase at every  
point in the AC cycle.


So, because of the different ways of specifying PF, it is always  
best to think of Power Factor as being the ratio of real (in  
phase) power, or VA to reactive power (VARS or "Volt Ampere  
Reactive").   That will work in all cases. (Real Vs. Apparent  
power is the same thing).   Apparent power is what you get when  
you multiply
your RMS meter's Voltage by the RMS current and is called VA Volt  
Amperes)   V x A will be the highest measured number, that is  
unless the PF = 1.0 in which

case both will measure the same.

Some of that measured VA, or apparent power will be "in phase"  
and is the "real" or "true" power.  Some of that VA may be  
reactive, (inductive or capacitive that

Re: [RE-wrenches] Power Factor

[boB Gudgel]

Chris Worcester wrote:

Has he checked the torque on all the battery connections?

Sincerely,

Chris Worcester
Solar Wind Works
NABCEP Certified PV Installer
Phone: 530-582-4503
Fax: 530-582-4603
www.solarwindworks.com
ch...@solarwindworks.com
"Proven Energy Solutions"

  


Also, Evidence of a bad battery connection (or bad inverter) should be 
obvious if the house lights dim

when the pump tries to start.

boB








-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Matt
Sent: Thursday, July 30, 2009 3:25 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Power Factor

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna
AE 48. Or rather, he isn't. According to him when he first fired it up, it
operated the pump just fine. The next time he tried, though. he couldn't
even get a buzz out of the starter. No workee.

The inverter runs all the other loads in the house fine, just not the pump.
He can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think not), a
motor starter problem or an inverter issue? I have to admit to being
somewhat baffled by this one because it ran the pump once, but not after.

Matt T


 boB Gudgel  wrote: 
  

boB Gudgel wrote:

 >>So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, or 
VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
work in all cases.



OOOps !   See, this can get confusing.   Reverse what I just said  Power 
Factor... " Definition: The ratio of true power to apparent power"  as 
David Brearley had just posted.  Otherwise, that calculation can give 
you an answer that is GREATER than 1.0 and you don't want that !


Had to eat some of my words.  I just wanted to point out that the phase 
shift method was called DPF.   Didn't Ian Woodenden do an article on PF
recently too ?  If not, he or someone probably should in one of the two 
HP magazines.


boB



R. Walters wrote:
  
Power factor expresses the time difference  between voltage peak and 
current peak on each of their sine waves. If both current and voltage 
waves are "in time", (their wave peaks match up) power factor is 1. 
If one is ahead or behind the other, it's not. Think about an 
electric motor: we hit it with a voltage wave, and a fraction of a 
second later, it actually moves, and the current wave happens. There 
is a little lag there. Resistive loads like lights have very little 
lag, and big electric motors coming up to speed can have horrible PF.

This definition of power factor only applies for linear loads with 
only inductance or capacitance (with resistance) and is called 
"Displacement Power Factor (DPF) and you will  see that on some power 
meters.


For non-linear loads, like battery chargers or computer power supplies 
without PF Correction,  the current waveform (on an O-scope) looks 
nothing like a sine or cosine wave.   The current "spikes up" at the 
AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
the current and the voltage do NOT look the same.  It's non-linear.  
Lower than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a PF of 
1.0,  the current and voltage waveform will both look exactly the same 
AND there will be no phase shift.   They are both linear and all 
current and voltage is in phase at every point in the AC cycle.


So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, 
or VA to reactive power (VARS or "Volt Ampere Reactive").   That will 
work in all cases. (Real Vs. Apparent power is the same thing).   
Apparent power is what you get when you multiply
your RMS meter's Voltage by the RMS current and is called VA Volt 
Amperes)   V x A will be the highest measured number, that is unless 
the PF = 1.0 in which

case both will measure the same.

Some of that measured VA, or apparent power will be "in phase" and is 
the "real" or "true" power.  Some of that VA may be reactive, 
(inductive or capacitive that is) and is the "out of phase" portion.  
Capacitive and inductive reactance is ALWAYS 90 degrees out of phase 
in current and voltage It's just a matter of how MUCH of your 
power is 0 degrees phase shift and how MUCH of that VA is  + or - 90 
degrees out of phase.  If  ALL of the current is in phase with the 
voltage, then
the power factor is 1.0.   That is, if you lay them on top of each 
other, they will look the same on an oscilloscope if power factor = 1.0


It can get way more complicated t

Re: [RE-wrenches] Power Factor

[Chris Worcester]

Has he checked the torque on all the battery connections?

Sincerely,

Chris Worcester
Solar Wind Works
NABCEP Certified PV Installer
Phone: 530-582-4503
Fax: 530-582-4603
www.solarwindworks.com
ch...@solarwindworks.com
"Proven Energy Solutions"


-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Matt
Sent: Thursday, July 30, 2009 3:25 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Power Factor

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna
AE 48. Or rather, he isn't. According to him when he first fired it up, it
operated the pump just fine. The next time he tried, though. he couldn't
even get a buzz out of the starter. No workee.

The inverter runs all the other loads in the house fine, just not the pump.
He can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think not), a
motor starter problem or an inverter issue? I have to admit to being
somewhat baffled by this one because it ran the pump once, but not after.

Matt T


 boB Gudgel  wrote: 
> boB Gudgel wrote:
> 
>  >>So, because of the different ways of specifying PF, it is always best 
> to think of Power Factor as being the ratio of real (in phase) power, or 
> VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
> work in all cases.
> 
> 
> OOOps !   See, this can get confusing.   Reverse what I just said  Power 
> Factor... " Definition: The ratio of true power to apparent power"  as 
> David Brearley had just posted.  Otherwise, that calculation can give 
> you an answer that is GREATER than 1.0 and you don't want that !
> 
> Had to eat some of my words.  I just wanted to point out that the phase 
> shift method was called DPF.   Didn't Ian Woodenden do an article on PF
> recently too ?  If not, he or someone probably should in one of the two 
> HP magazines.
> 
> boB
> 
> > R. Walters wrote:
> >> Power factor expresses the time difference  between voltage peak and 
> >> current peak on each of their sine waves. If both current and voltage 
> >> waves are "in time", (their wave peaks match up) power factor is 1. 
> >> If one is ahead or behind the other, it's not. Think about an 
> >> electric motor: we hit it with a voltage wave, and a fraction of a 
> >> second later, it actually moves, and the current wave happens. There 
> >> is a little lag there. Resistive loads like lights have very little 
> >> lag, and big electric motors coming up to speed can have horrible PF.
> >
> > This definition of power factor only applies for linear loads with 
> > only inductance or capacitance (with resistance) and is called 
> > "Displacement Power Factor (DPF) and you will  see that on some power 
> > meters.
> >
> > For non-linear loads, like battery chargers or computer power supplies 
> > without PF Correction,  the current waveform (on an O-scope) looks 
> > nothing like a sine or cosine wave.   The current "spikes up" at the 
> > AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
> > the current and the voltage do NOT look the same.  It's non-linear.  
> > Lower than 1.0 power factor for sure.
> >
> > For a grid tie inverter, resistive heater or any load that has a PF of 
> > 1.0,  the current and voltage waveform will both look exactly the same 
> > AND there will be no phase shift.   They are both linear and all 
> > current and voltage is in phase at every point in the AC cycle.
> >
> > So, because of the different ways of specifying PF, it is always best 
> > to think of Power Factor as being the ratio of real (in phase) power, 
> > or VA to reactive power (VARS or "Volt Ampere Reactive").   That will 
> > work in all cases. (Real Vs. Apparent power is the same thing).   
> > Apparent power is what you get when you multiply
> > your RMS meter's Voltage by the RMS current and is called VA Volt 
> > Amperes)   V x A will be the highest measured number, that is unless 
> > the PF = 1.0 in which
> > case both will measure the same.
> >
> > Some of that measured VA, or apparent power will be "in phase" and is 
> > the "real" or "true" power.  Some of that VA may be reactive, 
> > (inductive or capacitive that is) and is the "out of phase" portion.  
> > Capacitive and inductive reactance is ALWAYS 90 degrees out of phase 
> > in current and voltage It's just a matter of how MUC

Re: [RE-wrenches] Power Factor

[Ron Young]

Well, as it's the first grid-tie system in this region they are  
paying close attention. The guy I am dealing with is very stern and  
precise. I put down 100%, as they wanted a percentage. So we'll see.  
Thx all for the feedback, helpful as always!


Ron

On 30-Jul-09, at 5:58 PM, Allan Sindelar wrote:


Ron,
Why try to break it to them at all? Just answer the question. Put  
down 1.0
or unity. That's what they're looking for. Then go on to the next  
question.

They'll never catch it.

Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com

-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of boB  
Gudgel

Sent: Thursday, July 30, 2009 1:20 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Power Factor

Ron Young wrote:

Ok, so all seem to be in agreement more or less. How do I break it to
British Columbia Hydro? :-|

I think they must be misunderstanding what they are asking for but  
the

question is in the section for PV and on the same line as the total
output in Kwh of the PV. Power Factor %


It was most likely just  a trick question.

You're gonna fool them, though !   :)


boB





I'll contact them and see where this goes but I don't fully  
understand

what power factor is which will make it hard to argue my case. My
understanding is that it is the difference between what the utility
supplies to a residence vs. the actual loads being used by that
residence expressed as a percentage.

I came across the following course offering by SEI that discusses
Power Factor with reference to PV:

POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS
Presented By: Michael Smith of Alpine Management Systems



This session will deal with power factor: What is power factor?  What
causes low power factor?  Why improve
your power factor? This session will explain the role of power factor
correction as it applies to solar installations.
There are currently over 67,000 KVAR installations in 26 countries
resulting in phenomenal energy savings with
a corresponding reduction in greenhouse gas emissions. Session
includes several KVAR installations and the
resultant savings.
http://www.solarenergy.org/workshops/docs/ 
industry08_trainingdetails.pdf


Ron

On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:


There is no such thing as a power factor for DC or for panels.


.. 
..

..

Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/

.. 
..

..


- Original Message -
*From:* Ron Young <mailto:solarea...@solareagle.com>
*To:* RE-wrenches <mailto:re-wrenches@lists.re-wrenches.org>
*Sent:* Wednesday, July 29, 2009 5:45 PM
*Subject:* [RE-wrenches] Power Factor

Can anyone point me in the direction to find the power factor  
for

Sanyo HIT N 205 panels? The utility is requesting it on a net
metering interconnection application.

Ron Young
earthRight Products - Solareagle.com



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Re: [RE-wrenches] Power Factor

[Allan Sindelar]

Ron,
Why try to break it to them at all? Just answer the question. Put down 1.0
or unity. That's what they're looking for. Then go on to the next question.
They'll never catch it.

Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com

-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of boB Gudgel
Sent: Thursday, July 30, 2009 1:20 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Power Factor

Ron Young wrote:
> Ok, so all seem to be in agreement more or less. How do I break it to 
> British Columbia Hydro? :-|
>
> I think they must be misunderstanding what they are asking for but the 
> question is in the section for PV and on the same line as the total 
> output in Kwh of the PV. Power Factor %

It was most likely just  a trick question.

You're gonna fool them, though !   :)


boB



>
> I'll contact them and see where this goes but I don't fully understand 
> what power factor is which will make it hard to argue my case. My 
> understanding is that it is the difference between what the utility 
> supplies to a residence vs. the actual loads being used by that 
> residence expressed as a percentage. 
>
> I came across the following course offering by SEI that discusses 
> Power Factor with reference to PV:
>
> POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS 
> Presented By: Michael Smith of Alpine Management Systems 
>
>  
>
> This session will deal with power factor: What is power factor?  What 
> causes low power factor?  Why improve 
> your power factor? This session will explain the role of power factor 
> correction as it applies to solar installations. 
> There are currently over 67,000 KVAR installations in 26 countries 
> resulting in phenomenal energy savings with 
> a corresponding reduction in greenhouse gas emissions. Session 
> includes several KVAR installations and the 
> resultant savings. 
> http://www.solarenergy.org/workshops/docs/industry08_trainingdetails.pdf
>
> Ron
>
> On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:
>
>> There is no such thing as a power factor for DC or for panels.
>>  
>>

..
>> Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
>> Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
>>

..
>>
>> - Original Message -
>> *From:* Ron Young <mailto:solarea...@solareagle.com>
>> *To:* RE-wrenches <mailto:re-wrenches@lists.re-wrenches.org>
>> *Sent:* Wednesday, July 29, 2009 5:45 PM
>> *Subject:* [RE-wrenches] Power Factor
>>
>> Can anyone point me in the direction to find the power factor for
>> Sanyo HIT N 205 panels? The utility is requesting it on a net
>> metering interconnection application.  
>>
>> Ron Young
>> earthRight Products - Solareagle.com
>>
>>
>>

>>
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Re: [RE-wrenches] Power Factor

[Matt]

Hi Jay,

I think I'll check his wire connections at all the connection points first, and 
then the next time I'm in the area, bring my Fluke (which DOESN'T measure PF) 
for a closer look. Believe it or not, his meter is one of those mini GB 
thingies, analog of course, that would be better as a paper weight. The whole 
problem is really a hard thing to ferret out with face flies buzzing around 
your ears and eyes. :-(

Matt
 jay peltz  wrote: 
> Hi Matt,
> 
> I would try a few things, but its very curious to me that the inverter  
> won't even get a try out of the motor.
> I've seen plenty of motors not work, but they tried to start.
> 
> And given the 7k genny starts it, the 4k inverter should start it too.
> I would check the current under load and surge if possible.
> Check the battery voltage.
> Could be a bad cap on the motor too.
> 
> I've got a new meter that measures PF on the way, just for problems  
> like this.
> 
> jay
> 
> peltz power
> 
> 
> 
> On Jul 30, 2009, at 4:03 PM, Matt wrote:
> 
> > Unh - hunh, but it will run on the generator. If it didn't, I would  
> > go for the bad starter or motor, but it "seems" like the PF could be  
> > an issue??
> >
> > Matt T
> >  boB Gudgel  wrote:
> >> Matt wrote:
> >>> Possibly a PF question, or maybe one for Magnum - boB,
> >>>
> >>> One of the guys at work is (almost) running a 3/4 hp sub pump with  
> >>> a Magna AE 48. Or rather, he isn't. According to him when he first  
> >>> fired it up, it operated the pump just fine. The next time he  
> >>> tried, though. he couldn't even get a buzz out of the starter. No  
> >>> workee.
> >>>
> >> Sounds kind of like a "pump is broken or worn out" problem, doesn't  
> >> it ?
> >>
> >> If there is enough ac voltage applied to the pump, the it should do
> >> ~something~, or lights should dim or some
> >> kind of sign should show itself, wouldn't you think ?   Otherwise, I
> >> would suspect it might be a surge problem.
> >>
> >> Is there a pilot light or something ?   Maybe a fuse blew or breaker
> >> tripped somewhere ?   (when the pump went off?)
> >>
> >> Doesn't sound like a PF problem though... However,  since you mention
> >> it, with loads that are not a 1.0 power factor,
> >> at least for displacement power factor, when reactive phase shift is
> >> involved, the inverter must be able to "sink" current
> >> from the stored reactive energy as well as be a source to the motor.
> >> The Magnum does that just fine, as does any other
> >> decent inverter.
> >>
> >> Maybe Tony, Eldon or Gary at Magnum has seen this before ? 
> >> 425-353-8833
> >>
> >> boB
> >>
> >>
> >>
> >>
> >>
> >>
> >>> The inverter runs all the other loads in the house fine, just not  
> >>> the pump. He can run the pump directly from a 7 kW generator with  
> >>> no issues.
> >>> So, do you think we're looking at a power factor deficit,(I think  
> >>> not), a motor starter problem or an inverter issue? I have to  
> >>> admit to being somewhat baffled by this one because it ran the  
> >>> pump once, but not after.
> >>>
> >>> Matt T
> >>>
> >>>
> >>>  boB Gudgel  wrote:
> >>>
>  boB Gudgel wrote:
> 
> >> So, because of the different ways of specifying PF, it is  
> >> always best
>  to think of Power Factor as being the ratio of real (in phase)  
>  power, or
>  VA to reactive power >>(VARS or "Volt Ampere Reactive").   That  
>  will
>  work in all cases.
> 
> 
>  OOOps !   See, this can get confusing.   Reverse what I just  
>  said  Power
>  Factor... " Definition: The ratio of true power to apparent  
>  power"  as
>  David Brearley had just posted.  Otherwise, that calculation can  
>  give
>  you an answer that is GREATER than 1.0 and you don't want that !
> 
>  Had to eat some of my words.  I just wanted to point out that the  
>  phase
>  shift method was called DPF.   Didn't Ian Woodenden do an article  
>  on PF
>  recently too ?  If not, he or someone probably should in one of  
>  the two
>  HP magazines.
> 
>  boB
> 
> 
> > R. Walters wrote:
> >
> >> Power factor expresses the time difference  between voltage  
> >> peak and
> >> current peak on each of their sine waves. If both current and  
> >> voltage
> >> waves are "in time", (their wave peaks match up) power factor  
> >> is 1.
> >> If one is ahead or behind the other, it's not. Think about an
> >> electric motor: we hit it with a voltage wave, and a fraction  
> >> of a
> >> second later, it actually moves, and the current wave happens.  
> >> There
> >> is a little lag there. Resistive loads like lights have very  
> >> little
> >> lag, and big electric motors coming up to speed can have  
> >> horrible PF.
> >>
> > This definition of power factor only applies for linear loads with
> > only inductance or capacitance (with resistance) and is called
> 

Re: [RE-wrenches] Power Factor

[boB Gudgel]

jay peltz wrote:

Hi Matt,

I would try a few things, but its very curious to me that the inverter 
won't even get a try out of the motor.

I've seen plenty of motors not work, but they tried to start.

And given the 7k genny starts it, the 4k inverter should start it too.
I would check the current under load and surge if possible.
Check the battery voltage.
Could be a bad cap on the motor too.

I've got a new meter that measures PF on the way, just for problems 
like this.


jay

peltz power


Shall we try for 4 out of a million plus ??Maybe it's another  
dreaded CBI breaker ?


boB









On Jul 30, 2009, at 4:03 PM, Matt wrote:

Unh - hunh, but it will run on the generator. If it didn't, I would 
go for the bad starter or motor, but it "seems" like the PF could be 
an issue??


Matt T
 boB Gudgel  wrote:

Matt wrote:

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with 
a Magna AE 48. Or rather, he isn't. According to him when he first 
fired it up, it operated the pump just fine. The next time he 
tried, though. he couldn't even get a buzz out of the starter. No 
workee.


Sounds kind of like a "pump is broken or worn out" problem, doesn't 
it ?


If there is enough ac voltage applied to the pump, the it should do
~something~, or lights should dim or some
kind of sign should show itself, wouldn't you think ?   Otherwise, I
would suspect it might be a surge problem.

Is there a pilot light or something ?   Maybe a fuse blew or breaker
tripped somewhere ?   (when the pump went off?)

Doesn't sound like a PF problem though... However,  since you mention
it, with loads that are not a 1.0 power factor,
at least for displacement power factor, when reactive phase shift is
involved, the inverter must be able to "sink" current
from the stored reactive energy as well as be a source to the motor.
The Magnum does that just fine, as does any other
decent inverter.

Maybe Tony, Eldon or Gary at Magnum has seen this before ?
425-353-8833


boB






The inverter runs all the other loads in the house fine, just not 
the pump. He can run the pump directly from a 7 kW generator with 
no issues.
So, do you think we're looking at a power factor deficit,(I think 
not), a motor starter problem or an inverter issue? I have to admit 
to being somewhat baffled by this one because it ran the pump once, 
but not after.


Matt T


 boB Gudgel  wrote:


boB Gudgel wrote:

So, because of the different ways of specifying PF, it is always 
best
to think of Power Factor as being the ratio of real (in phase) 
power, or

VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will
work in all cases.


OOOps !   See, this can get confusing.   Reverse what I just said  
Power
Factor... " Definition: The ratio of true power to apparent 
power"  as

David Brearley had just posted.  Otherwise, that calculation can give
you an answer that is GREATER than 1.0 and you don't want that !

Had to eat some of my words.  I just wanted to point out that the 
phase
shift method was called DPF.   Didn't Ian Woodenden do an article 
on PF
recently too ?  If not, he or someone probably should in one of 
the two

HP magazines.

boB



R. Walters wrote:

Power factor expresses the time difference  between voltage peak 
and
current peak on each of their sine waves. If both current and 
voltage

waves are "in time", (their wave peaks match up) power factor is 1.
If one is ahead or behind the other, it's not. Think about an
electric motor: we hit it with a voltage wave, and a fraction of a
second later, it actually moves, and the current wave happens. 
There

is a little lag there. Resistive loads like lights have very little
lag, and big electric motors coming up to speed can have 
horrible PF.



This definition of power factor only applies for linear loads with
only inductance or capacitance (with resistance) and is called
"Displacement Power Factor (DPF) and you will  see that on some 
power

meters.

For non-linear loads, like battery chargers or computer power 
supplies

without PF Correction,  the current waveform (on an O-scope) looks
nothing like a sine or cosine wave.   The current "spikes up" at the
AC voltage peaks.  It actually *looks like* it might be in phase, 
BUT

the current and the voltage do NOT look the same.  It's non-linear.
Lower than 1.0 power factor for sure.

For a grid tie inverter, resistive heater or any load that has a 
PF of
1.0,  the current and voltage waveform will both look exactly the 
same

AND there will be no phase shift.   They are both linear and all
current and voltage is in phase at every point in the AC cycle.

So, because of the different ways of specifying PF, it is always 
best
to think of Power Factor as being the ratio of real (in phase) 
power,
or VA to reactive power (VARS or "Volt Ampere Reactive").   That 
will

work in all cases. (Real Vs. Apparent power is the same thing).
Apparent power is what you get whe

Re: [RE-wrenches] Power Factor

[jay peltz]

Hi Matt,

I would try a few things, but its very curious to me that the inverter  
won't even get a try out of the motor.

I've seen plenty of motors not work, but they tried to start.

And given the 7k genny starts it, the 4k inverter should start it too.
I would check the current under load and surge if possible.
Check the battery voltage.
Could be a bad cap on the motor too.

I've got a new meter that measures PF on the way, just for problems  
like this.


jay

peltz power



On Jul 30, 2009, at 4:03 PM, Matt wrote:

Unh - hunh, but it will run on the generator. If it didn't, I would  
go for the bad starter or motor, but it "seems" like the PF could be  
an issue??


Matt T
 boB Gudgel  wrote:

Matt wrote:

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with  
a Magna AE 48. Or rather, he isn't. According to him when he first  
fired it up, it operated the pump just fine. The next time he  
tried, though. he couldn't even get a buzz out of the starter. No  
workee.


Sounds kind of like a "pump is broken or worn out" problem, doesn't  
it ?


If there is enough ac voltage applied to the pump, the it should do
~something~, or lights should dim or some
kind of sign should show itself, wouldn't you think ?   Otherwise, I
would suspect it might be a surge problem.

Is there a pilot light or something ?   Maybe a fuse blew or breaker
tripped somewhere ?   (when the pump went off?)

Doesn't sound like a PF problem though... However,  since you mention
it, with loads that are not a 1.0 power factor,
at least for displacement power factor, when reactive phase shift is
involved, the inverter must be able to "sink" current
from the stored reactive energy as well as be a source to the motor.
The Magnum does that just fine, as does any other
decent inverter.

Maybe Tony, Eldon or Gary at Magnum has seen this before ? 
425-353-8833


boB






The inverter runs all the other loads in the house fine, just not  
the pump. He can run the pump directly from a 7 kW generator with  
no issues.
So, do you think we're looking at a power factor deficit,(I think  
not), a motor starter problem or an inverter issue? I have to  
admit to being somewhat baffled by this one because it ran the  
pump once, but not after.


Matt T


 boB Gudgel  wrote:


boB Gudgel wrote:

So, because of the different ways of specifying PF, it is  
always best
to think of Power Factor as being the ratio of real (in phase)  
power, or
VA to reactive power >>(VARS or "Volt Ampere Reactive").   That  
will

work in all cases.


OOOps !   See, this can get confusing.   Reverse what I just  
said  Power
Factor... " Definition: The ratio of true power to apparent  
power"  as
David Brearley had just posted.  Otherwise, that calculation can  
give

you an answer that is GREATER than 1.0 and you don't want that !

Had to eat some of my words.  I just wanted to point out that the  
phase
shift method was called DPF.   Didn't Ian Woodenden do an article  
on PF
recently too ?  If not, he or someone probably should in one of  
the two

HP magazines.

boB



R. Walters wrote:

Power factor expresses the time difference  between voltage  
peak and
current peak on each of their sine waves. If both current and  
voltage
waves are "in time", (their wave peaks match up) power factor  
is 1.

If one is ahead or behind the other, it's not. Think about an
electric motor: we hit it with a voltage wave, and a fraction  
of a
second later, it actually moves, and the current wave happens.  
There
is a little lag there. Resistive loads like lights have very  
little
lag, and big electric motors coming up to speed can have  
horrible PF.



This definition of power factor only applies for linear loads with
only inductance or capacitance (with resistance) and is called
"Displacement Power Factor (DPF) and you will  see that on some  
power

meters.

For non-linear loads, like battery chargers or computer power  
supplies

without PF Correction,  the current waveform (on an O-scope) looks
nothing like a sine or cosine wave.   The current "spikes up" at  
the
AC voltage peaks.  It actually *looks like* it might be in  
phase, BUT
the current and the voltage do NOT look the same.  It's non- 
linear.

Lower than 1.0 power factor for sure.

For a grid tie inverter, resistive heater or any load that has a  
PF of
1.0,  the current and voltage waveform will both look exactly  
the same

AND there will be no phase shift.   They are both linear and all
current and voltage is in phase at every point in the AC cycle.

So, because of the different ways of specifying PF, it is always  
best
to think of Power Factor as being the ratio of real (in phase)  
power,
or VA to reactive power (VARS or "Volt Ampere Reactive").   That  
will

work in all cases. (Real Vs. Apparent power is the same thing).
Apparent power is what you get when you multiply
your RMS meter's Voltage by the RMS current and is called VA

Re: [RE-wrenches] Power Factor

[boB Gudgel]

Matt wrote:

Unh - hunh, but it will run on the generator. If it didn't, I would go for the bad 
starter or motor, but it "seems" like the PF could be an issue??

Matt T
  


Well, an inverter is just (supposed to be) a low impedance Voltage 
Source and the current does whatever it is going to do... And what that 
current - voltage

relationship is, is definitely related to power factor.

Is the generator (which works fine) passing ~through~ the Magnum and out 
to the loads and pump ?  If so, then you know it's not a high
resistance circuit or loose terminal block screw I guess.   If the 
generator goes around the Magnum AE internal relays then I would

suspect a high resistance connection somewhere.

I would measure the voltage at the pump and note what it does when the 
pump is switched on from the inverter.
I bet you a drink, (next time I see you), that the voltage drops to zero 
or at least very low.


boB







 boB Gudgel  wrote: 
  

Matt wrote:


Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna AE 
48. Or rather, he isn't. According to him when he first fired it up, it 
operated the pump just fine. The next time he tried, though. he couldn't even 
get a buzz out of the starter. No workee.
  
  

Sounds kind of like a "pump is broken or worn out" problem, doesn't it ?

If there is enough ac voltage applied to the pump, the it should do 
~something~, or lights should dim or some
kind of sign should show itself, wouldn't you think ?   Otherwise, I 
would suspect it might be a surge problem.


Is there a pilot light or something ?   Maybe a fuse blew or breaker 
tripped somewhere ?   (when the pump went off?)


Doesn't sound like a PF problem though... However,  since you mention 
it, with loads that are not a 1.0 power factor,
at least for displacement power factor, when reactive phase shift is 
involved, the inverter must be able to "sink" current
from the stored reactive energy as well as be a source to the motor.   
The Magnum does that just fine, as does any other

decent inverter.

Maybe Tony, Eldon or Gary at Magnum has seen this before ?425-353-8833

boB








The inverter runs all the other loads in the house fine, just not the pump. He 
can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think not), a motor 
starter problem or an inverter issue? I have to admit to being somewhat baffled 
by this one because it ran the pump once, but not after.

Matt T


 boB Gudgel  wrote: 
  
  

boB Gudgel wrote:

 >>So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, or 
VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
work in all cases.



OOOps !   See, this can get confusing.   Reverse what I just said  Power 
Factor... " Definition: The ratio of true power to apparent power"  as 
David Brearley had just posted.  Otherwise, that calculation can give 
you an answer that is GREATER than 1.0 and you don't want that !


Had to eat some of my words.  I just wanted to point out that the phase 
shift method was called DPF.   Didn't Ian Woodenden do an article on PF
recently too ?  If not, he or someone probably should in one of the two 
HP magazines.


boB




R. Walters wrote:
  
  
Power factor expresses the time difference  between voltage peak and 
current peak on each of their sine waves. If both current and voltage 
waves are "in time", (their wave peaks match up) power factor is 1. 
If one is ahead or behind the other, it's not. Think about an 
electric motor: we hit it with a voltage wave, and a fraction of a 
second later, it actually moves, and the current wave happens. There 
is a little lag there. Resistive loads like lights have very little 
lag, and big electric motors coming up to speed can have horrible PF.


This definition of power factor only applies for linear loads with 
only inductance or capacitance (with resistance) and is called 
"Displacement Power Factor (DPF) and you will  see that on some power 
meters.


For non-linear loads, like battery chargers or computer power supplies 
without PF Correction,  the current waveform (on an O-scope) looks 
nothing like a sine or cosine wave.   The current "spikes up" at the 
AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
the current and the voltage do NOT look the same.  It's non-linear.  
Lower than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a PF of 
1.0,  the current and voltage waveform will both look exactly the same 
AND there will be no phase shift.   They are both linear and all 
current and voltage is in phase at every point in the AC cycle.


So, because of the different ways of specifying PF, it is always best 
to think of Power F

Re: [RE-wrenches] Power Factor

[Matt]

Unh - hunh, but it will run on the generator. If it didn't, I would go for the 
bad starter or motor, but it "seems" like the PF could be an issue??

Matt T
 boB Gudgel  wrote: 
> Matt wrote:
> > Possibly a PF question, or maybe one for Magnum - boB,
> >
> > One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna 
> > AE 48. Or rather, he isn't. According to him when he first fired it up, it 
> > operated the pump just fine. The next time he tried, though. he couldn't 
> > even get a buzz out of the starter. No workee.
> >   
> Sounds kind of like a "pump is broken or worn out" problem, doesn't it ?
> 
> If there is enough ac voltage applied to the pump, the it should do 
> ~something~, or lights should dim or some
> kind of sign should show itself, wouldn't you think ?   Otherwise, I 
> would suspect it might be a surge problem.
> 
> Is there a pilot light or something ?   Maybe a fuse blew or breaker 
> tripped somewhere ?   (when the pump went off?)
> 
> Doesn't sound like a PF problem though... However,  since you mention 
> it, with loads that are not a 1.0 power factor,
> at least for displacement power factor, when reactive phase shift is 
> involved, the inverter must be able to "sink" current
> from the stored reactive energy as well as be a source to the motor.   
> The Magnum does that just fine, as does any other
> decent inverter.
> 
> Maybe Tony, Eldon or Gary at Magnum has seen this before ?425-353-8833
> 
> boB
> 
> 
> 
> 
> 
> 
> > The inverter runs all the other loads in the house fine, just not the pump. 
> > He can run the pump directly from a 7 kW generator with no issues.
> > So, do you think we're looking at a power factor deficit,(I think not), a 
> > motor starter problem or an inverter issue? I have to admit to being 
> > somewhat baffled by this one because it ran the pump once, but not after.
> >
> > Matt T
> >
> >
> >  boB Gudgel  wrote: 
> >   
> >> boB Gudgel wrote:
> >>
> >>  >>So, because of the different ways of specifying PF, it is always best 
> >> to think of Power Factor as being the ratio of real (in phase) power, or 
> >> VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
> >> work in all cases.
> >>
> >>
> >> OOOps !   See, this can get confusing.   Reverse what I just said  Power 
> >> Factor... " Definition: The ratio of true power to apparent power"  as 
> >> David Brearley had just posted.  Otherwise, that calculation can give 
> >> you an answer that is GREATER than 1.0 and you don't want that !
> >>
> >> Had to eat some of my words.  I just wanted to point out that the phase 
> >> shift method was called DPF.   Didn't Ian Woodenden do an article on PF
> >> recently too ?  If not, he or someone probably should in one of the two 
> >> HP magazines.
> >>
> >> boB
> >>
> >> 
> >>> R. Walters wrote:
> >>>   
>  Power factor expresses the time difference  between voltage peak and 
>  current peak on each of their sine waves. If both current and voltage 
>  waves are "in time", (their wave peaks match up) power factor is 1. 
>  If one is ahead or behind the other, it's not. Think about an 
>  electric motor: we hit it with a voltage wave, and a fraction of a 
>  second later, it actually moves, and the current wave happens. There 
>  is a little lag there. Resistive loads like lights have very little 
>  lag, and big electric motors coming up to speed can have horrible PF.
>  
> >>> This definition of power factor only applies for linear loads with 
> >>> only inductance or capacitance (with resistance) and is called 
> >>> "Displacement Power Factor (DPF) and you will  see that on some power 
> >>> meters.
> >>>
> >>> For non-linear loads, like battery chargers or computer power supplies 
> >>> without PF Correction,  the current waveform (on an O-scope) looks 
> >>> nothing like a sine or cosine wave.   The current "spikes up" at the 
> >>> AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
> >>> the current and the voltage do NOT look the same.  It's non-linear.  
> >>> Lower than 1.0 power factor for sure.
> >>>
> >>> For a grid tie inverter, resistive heater or any load that has a PF of 
> >>> 1.0,  the current and voltage waveform will both look exactly the same 
> >>> AND there will be no phase shift.   They are both linear and all 
> >>> current and voltage is in phase at every point in the AC cycle.
> >>>
> >>> So, because of the different ways of specifying PF, it is always best 
> >>> to think of Power Factor as being the ratio of real (in phase) power, 
> >>> or VA to reactive power (VARS or "Volt Ampere Reactive").   That will 
> >>> work in all cases. (Real Vs. Apparent power is the same thing).   
> >>> Apparent power is what you get when you multiply
> >>> your RMS meter's Voltage by the RMS current and is called VA Volt 
> >>> Amperes)   V x A will be the highest measured number, that is unless 
> >>> the PF = 1.0 in which
> >>> c

Re: [RE-wrenches] Power Factor

[Matt]

Unh - hunh, but it will run on the generator. If it didn't, I would go for the 
bad starter or motor, but it "seems" like the PF could be an issue??

Matt T
 boB Gudgel  wrote: 
> Matt wrote:
> > Possibly a PF question, or maybe one for Magnum - boB,
> >
> > One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna 
> > AE 48. Or rather, he isn't. According to him when he first fired it up, it 
> > operated the pump just fine. The next time he tried, though. he couldn't 
> > even get a buzz out of the starter. No workee.
> >   
> Sounds kind of like a "pump is broken or worn out" problem, doesn't it ?
> 
> If there is enough ac voltage applied to the pump, the it should do 
> ~something~, or lights should dim or some
> kind of sign should show itself, wouldn't you think ?   Otherwise, I 
> would suspect it might be a surge problem.
> 
> Is there a pilot light or something ?   Maybe a fuse blew or breaker 
> tripped somewhere ?   (when the pump went off?)
> 
> Doesn't sound like a PF problem though... However,  since you mention 
> it, with loads that are not a 1.0 power factor,
> at least for displacement power factor, when reactive phase shift is 
> involved, the inverter must be able to "sink" current
> from the stored reactive energy as well as be a source to the motor.   
> The Magnum does that just fine, as does any other
> decent inverter.
> 
> Maybe Tony, Eldon or Gary at Magnum has seen this before ?425-353-8833
> 
> boB
> 
> 
> 
> 
> 
> 
> > The inverter runs all the other loads in the house fine, just not the pump. 
> > He can run the pump directly from a 7 kW generator with no issues.
> > So, do you think we're looking at a power factor deficit,(I think not), a 
> > motor starter problem or an inverter issue? I have to admit to being 
> > somewhat baffled by this one because it ran the pump once, but not after.
> >
> > Matt T
> >
> >
> >  boB Gudgel  wrote: 
> >   
> >> boB Gudgel wrote:
> >>
> >>  >>So, because of the different ways of specifying PF, it is always best 
> >> to think of Power Factor as being the ratio of real (in phase) power, or 
> >> VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
> >> work in all cases.
> >>
> >>
> >> OOOps !   See, this can get confusing.   Reverse what I just said  Power 
> >> Factor... " Definition: The ratio of true power to apparent power"  as 
> >> David Brearley had just posted.  Otherwise, that calculation can give 
> >> you an answer that is GREATER than 1.0 and you don't want that !
> >>
> >> Had to eat some of my words.  I just wanted to point out that the phase 
> >> shift method was called DPF.   Didn't Ian Woodenden do an article on PF
> >> recently too ?  If not, he or someone probably should in one of the two 
> >> HP magazines.
> >>
> >> boB
> >>
> >> 
> >>> R. Walters wrote:
> >>>   
>  Power factor expresses the time difference  between voltage peak and 
>  current peak on each of their sine waves. If both current and voltage 
>  waves are "in time", (their wave peaks match up) power factor is 1. 
>  If one is ahead or behind the other, it's not. Think about an 
>  electric motor: we hit it with a voltage wave, and a fraction of a 
>  second later, it actually moves, and the current wave happens. There 
>  is a little lag there. Resistive loads like lights have very little 
>  lag, and big electric motors coming up to speed can have horrible PF.
>  
> >>> This definition of power factor only applies for linear loads with 
> >>> only inductance or capacitance (with resistance) and is called 
> >>> "Displacement Power Factor (DPF) and you will  see that on some power 
> >>> meters.
> >>>
> >>> For non-linear loads, like battery chargers or computer power supplies 
> >>> without PF Correction,  the current waveform (on an O-scope) looks 
> >>> nothing like a sine or cosine wave.   The current "spikes up" at the 
> >>> AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
> >>> the current and the voltage do NOT look the same.  It's non-linear.  
> >>> Lower than 1.0 power factor for sure.
> >>>
> >>> For a grid tie inverter, resistive heater or any load that has a PF of 
> >>> 1.0,  the current and voltage waveform will both look exactly the same 
> >>> AND there will be no phase shift.   They are both linear and all 
> >>> current and voltage is in phase at every point in the AC cycle.
> >>>
> >>> So, because of the different ways of specifying PF, it is always best 
> >>> to think of Power Factor as being the ratio of real (in phase) power, 
> >>> or VA to reactive power (VARS or "Volt Ampere Reactive").   That will 
> >>> work in all cases. (Real Vs. Apparent power is the same thing).   
> >>> Apparent power is what you get when you multiply
> >>> your RMS meter's Voltage by the RMS current and is called VA Volt 
> >>> Amperes)   V x A will be the highest measured number, that is unless 
> >>> the PF = 1.0 in which
> >>> c

Re: [RE-wrenches] Power Factor

[boB Gudgel]

Matt wrote:

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna AE 
48. Or rather, he isn't. According to him when he first fired it up, it 
operated the pump just fine. The next time he tried, though. he couldn't even 
get a buzz out of the starter. No workee.
  

Sounds kind of like a "pump is broken or worn out" problem, doesn't it ?

If there is enough ac voltage applied to the pump, the it should do 
~something~, or lights should dim or some
kind of sign should show itself, wouldn't you think ?   Otherwise, I 
would suspect it might be a surge problem.


Is there a pilot light or something ?   Maybe a fuse blew or breaker 
tripped somewhere ?   (when the pump went off?)


Doesn't sound like a PF problem though... However,  since you mention 
it, with loads that are not a 1.0 power factor,
at least for displacement power factor, when reactive phase shift is 
involved, the inverter must be able to "sink" current
from the stored reactive energy as well as be a source to the motor.   
The Magnum does that just fine, as does any other

decent inverter.

Maybe Tony, Eldon or Gary at Magnum has seen this before ?425-353-8833

boB







The inverter runs all the other loads in the house fine, just not the pump. He 
can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think not), a motor 
starter problem or an inverter issue? I have to admit to being somewhat baffled 
by this one because it ran the pump once, but not after.

Matt T


 boB Gudgel  wrote: 
  

boB Gudgel wrote:

 >>So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, or 
VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
work in all cases.



OOOps !   See, this can get confusing.   Reverse what I just said  Power 
Factor... " Definition: The ratio of true power to apparent power"  as 
David Brearley had just posted.  Otherwise, that calculation can give 
you an answer that is GREATER than 1.0 and you don't want that !


Had to eat some of my words.  I just wanted to point out that the phase 
shift method was called DPF.   Didn't Ian Woodenden do an article on PF
recently too ?  If not, he or someone probably should in one of the two 
HP magazines.


boB



R. Walters wrote:
  
Power factor expresses the time difference  between voltage peak and 
current peak on each of their sine waves. If both current and voltage 
waves are "in time", (their wave peaks match up) power factor is 1. 
If one is ahead or behind the other, it's not. Think about an 
electric motor: we hit it with a voltage wave, and a fraction of a 
second later, it actually moves, and the current wave happens. There 
is a little lag there. Resistive loads like lights have very little 
lag, and big electric motors coming up to speed can have horrible PF.

This definition of power factor only applies for linear loads with 
only inductance or capacitance (with resistance) and is called 
"Displacement Power Factor (DPF) and you will  see that on some power 
meters.


For non-linear loads, like battery chargers or computer power supplies 
without PF Correction,  the current waveform (on an O-scope) looks 
nothing like a sine or cosine wave.   The current "spikes up" at the 
AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
the current and the voltage do NOT look the same.  It's non-linear.  
Lower than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a PF of 
1.0,  the current and voltage waveform will both look exactly the same 
AND there will be no phase shift.   They are both linear and all 
current and voltage is in phase at every point in the AC cycle.


So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, 
or VA to reactive power (VARS or "Volt Ampere Reactive").   That will 
work in all cases. (Real Vs. Apparent power is the same thing).   
Apparent power is what you get when you multiply
your RMS meter's Voltage by the RMS current and is called VA Volt 
Amperes)   V x A will be the highest measured number, that is unless 
the PF = 1.0 in which

case both will measure the same.

Some of that measured VA, or apparent power will be "in phase" and is 
the "real" or "true" power.  Some of that VA may be reactive, 
(inductive or capacitive that is) and is the "out of phase" portion.  
Capacitive and inductive reactance is ALWAYS 90 degrees out of phase 
in current and voltage It's just a matter of how MUCH of your 
power is 0 degrees phase shift and how MUCH of that VA is  + or - 90 
degrees out of phase.  If  ALL of the current is in phase with the 
voltage, then
the power factor is 1.0.   That is, if you lay them on top of each 
other, they will look 

Re: [RE-wrenches] Power Factor

[Matt]

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna AE 
48. Or rather, he isn't. According to him when he first fired it up, it 
operated the pump just fine. The next time he tried, though. he couldn't even 
get a buzz out of the starter. No workee.

The inverter runs all the other loads in the house fine, just not the pump. He 
can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think not), a motor 
starter problem or an inverter issue? I have to admit to being somewhat baffled 
by this one because it ran the pump once, but not after.

Matt T


 boB Gudgel  wrote: 
> boB Gudgel wrote:
> 
>  >>So, because of the different ways of specifying PF, it is always best 
> to think of Power Factor as being the ratio of real (in phase) power, or 
> VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
> work in all cases.
> 
> 
> OOOps !   See, this can get confusing.   Reverse what I just said  Power 
> Factor... " Definition: The ratio of true power to apparent power"  as 
> David Brearley had just posted.  Otherwise, that calculation can give 
> you an answer that is GREATER than 1.0 and you don't want that !
> 
> Had to eat some of my words.  I just wanted to point out that the phase 
> shift method was called DPF.   Didn't Ian Woodenden do an article on PF
> recently too ?  If not, he or someone probably should in one of the two 
> HP magazines.
> 
> boB
> 
> > R. Walters wrote:
> >> Power factor expresses the time difference  between voltage peak and 
> >> current peak on each of their sine waves. If both current and voltage 
> >> waves are "in time", (their wave peaks match up) power factor is 1. 
> >> If one is ahead or behind the other, it's not. Think about an 
> >> electric motor: we hit it with a voltage wave, and a fraction of a 
> >> second later, it actually moves, and the current wave happens. There 
> >> is a little lag there. Resistive loads like lights have very little 
> >> lag, and big electric motors coming up to speed can have horrible PF.
> >
> > This definition of power factor only applies for linear loads with 
> > only inductance or capacitance (with resistance) and is called 
> > "Displacement Power Factor (DPF) and you will  see that on some power 
> > meters.
> >
> > For non-linear loads, like battery chargers or computer power supplies 
> > without PF Correction,  the current waveform (on an O-scope) looks 
> > nothing like a sine or cosine wave.   The current "spikes up" at the 
> > AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
> > the current and the voltage do NOT look the same.  It's non-linear.  
> > Lower than 1.0 power factor for sure.
> >
> > For a grid tie inverter, resistive heater or any load that has a PF of 
> > 1.0,  the current and voltage waveform will both look exactly the same 
> > AND there will be no phase shift.   They are both linear and all 
> > current and voltage is in phase at every point in the AC cycle.
> >
> > So, because of the different ways of specifying PF, it is always best 
> > to think of Power Factor as being the ratio of real (in phase) power, 
> > or VA to reactive power (VARS or "Volt Ampere Reactive").   That will 
> > work in all cases. (Real Vs. Apparent power is the same thing).   
> > Apparent power is what you get when you multiply
> > your RMS meter's Voltage by the RMS current and is called VA Volt 
> > Amperes)   V x A will be the highest measured number, that is unless 
> > the PF = 1.0 in which
> > case both will measure the same.
> >
> > Some of that measured VA, or apparent power will be "in phase" and is 
> > the "real" or "true" power.  Some of that VA may be reactive, 
> > (inductive or capacitive that is) and is the "out of phase" portion.  
> > Capacitive and inductive reactance is ALWAYS 90 degrees out of phase 
> > in current and voltage It's just a matter of how MUCH of your 
> > power is 0 degrees phase shift and how MUCH of that VA is  + or - 90 
> > degrees out of phase.  If  ALL of the current is in phase with the 
> > voltage, then
> > the power factor is 1.0.   That is, if you lay them on top of each 
> > other, they will look the same on an oscilloscope if power factor = 1.0
> >
> > It can get way more complicated that this too, but that's basically 
> > it.  Feel free to add to this.
> >
> > boB
> >
> >
> >
> > power meters.
> >
> >
> >> There is much more to it, with reactance, "real" and "imaginary" 
> >> numbers?!, etc. but basically, we wrenches need to know that 
> >> everybody wants  Power factor to be close to 1.
> >> Obviously there isn't PF on DC, and it is my understanding that most 
> >> inverters can operate at most power factors. Not 100% sure, but I 
> >> think GT inverters would help not hurt the PF problem in most 
> >> situations.
> >>
> >> Correct me on any and all of this, Oh fellow wrenches,
> >>
> >>

Re: [RE-wrenches] Power Factor

[boB Gudgel]

boB Gudgel wrote:

>>So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, or 
VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
work in all cases.



OOOps !   See, this can get confusing.   Reverse what I just said  Power 
Factor... " Definition: The ratio of true power to apparent power"  as 
David Brearley had just posted.  Otherwise, that calculation can give 
you an answer that is GREATER than 1.0 and you don't want that !


Had to eat some of my words.  I just wanted to point out that the phase 
shift method was called DPF.   Didn't Ian Woodenden do an article on PF
recently too ?  If not, he or someone probably should in one of the two 
HP magazines.


boB


R. Walters wrote:
Power factor expresses the time difference  between voltage peak and 
current peak on each of their sine waves. If both current and voltage 
waves are "in time", (their wave peaks match up) power factor is 1. 
If one is ahead or behind the other, it's not. Think about an 
electric motor: we hit it with a voltage wave, and a fraction of a 
second later, it actually moves, and the current wave happens. There 
is a little lag there. Resistive loads like lights have very little 
lag, and big electric motors coming up to speed can have horrible PF.


This definition of power factor only applies for linear loads with 
only inductance or capacitance (with resistance) and is called 
"Displacement Power Factor (DPF) and you will  see that on some power 
meters.


For non-linear loads, like battery chargers or computer power supplies 
without PF Correction,  the current waveform (on an O-scope) looks 
nothing like a sine or cosine wave.   The current "spikes up" at the 
AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
the current and the voltage do NOT look the same.  It's non-linear.  
Lower than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a PF of 
1.0,  the current and voltage waveform will both look exactly the same 
AND there will be no phase shift.   They are both linear and all 
current and voltage is in phase at every point in the AC cycle.


So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, 
or VA to reactive power (VARS or "Volt Ampere Reactive").   That will 
work in all cases. (Real Vs. Apparent power is the same thing).   
Apparent power is what you get when you multiply
your RMS meter's Voltage by the RMS current and is called VA Volt 
Amperes)   V x A will be the highest measured number, that is unless 
the PF = 1.0 in which

case both will measure the same.

Some of that measured VA, or apparent power will be "in phase" and is 
the "real" or "true" power.  Some of that VA may be reactive, 
(inductive or capacitive that is) and is the "out of phase" portion.  
Capacitive and inductive reactance is ALWAYS 90 degrees out of phase 
in current and voltage It's just a matter of how MUCH of your 
power is 0 degrees phase shift and how MUCH of that VA is  + or - 90 
degrees out of phase.  If  ALL of the current is in phase with the 
voltage, then
the power factor is 1.0.   That is, if you lay them on top of each 
other, they will look the same on an oscilloscope if power factor = 1.0


It can get way more complicated that this too, but that's basically 
it.  Feel free to add to this.


boB



power meters.


There is much more to it, with reactance, "real" and "imaginary" 
numbers?!, etc. but basically, we wrenches need to know that 
everybody wants  Power factor to be close to 1.
Obviously there isn't PF on DC, and it is my understanding that most 
inverters can operate at most power factors. Not 100% sure, but I 
think GT inverters would help not hurt the PF problem in most 
situations.


Correct me on any and all of this, Oh fellow wrenches,

R. Walters
Solarray.com
NABCEP # 04170442















On Jul 30, 2009, at 9:19 AM, boB Gudgel wrote:


Ron Young wrote:
Ok, so all seem to be in agreement more or less. How do I break it 
to British Columbia Hydro? :-|


I think they must be misunderstanding what they are asking for but 
the question is in the section for PV and on the same line as the 
total output in Kwh of the PV. Power Factor %


It was most likely just  a trick question.

You're gonna fool them, though !   :)


boB





I'll contact them and see where this goes but I don't fully 
understand what power factor is which will make it hard to argue my 
case. My understanding is that it is the difference between what 
the utility supplies to a residence vs. the actual loads being used 
by that residence expressed as a percentage. I came across the 
following course offering by SEI that discusses Power Factor with 
reference to PV:


POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS Presented By: 
Michael Smith of Alpine Management Systems  
This sessio

Re: [RE-wrenches] Power Factor

[boB Gudgel]

R. Walters wrote:
Power factor expresses the time difference  between voltage peak and 
current peak on each of their sine waves. If both current and voltage 
waves are "in time", (their wave peaks match up) power factor is 1. If 
one is ahead or behind the other, it's not. Think about an electric 
motor: we hit it with a voltage wave, and a fraction of a second 
later, it actually moves, and the current wave happens. There is a 
little lag there. Resistive loads like lights have very little lag, 
and big electric motors coming up to speed can have horrible PF.


This definition of power factor only applies for linear loads with only 
inductance or capacitance (with resistance) and is called "Displacement 
Power Factor (DPF) and you will  see that on some power meters.


For non-linear loads, like battery chargers or computer power supplies 
without PF Correction,  the current waveform (on an O-scope) looks 
nothing like a sine or cosine wave.   The current "spikes up" at the AC 
voltage peaks.  It actually *looks like* it might be in phase, BUT the 
current and the voltage do NOT look the same.  It's non-linear.  Lower 
than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a PF of 
1.0,  the current and voltage waveform will both look exactly the same 
AND there will be no phase shift.   They are both linear and all current 
and voltage is in phase at every point in the AC cycle.


So, because of the different ways of specifying PF, it is always best to 
think of Power Factor as being the ratio of real (in phase) power, or VA 
to reactive power (VARS or "Volt Ampere Reactive").   That will work in 
all cases. (Real Vs. Apparent power is the same thing).   Apparent power 
is what you get when you multiply
your RMS meter's Voltage by the RMS current and is called VA Volt 
Amperes)   V x A will be the highest measured number, that is unless the 
PF = 1.0 in which

case both will measure the same.

Some of that measured VA, or apparent power will be "in phase" and is 
the "real" or "true" power.  Some of that VA may be reactive, (inductive 
or capacitive that is) and is the "out of phase" portion.  Capacitive 
and inductive reactance is ALWAYS 90 degrees out of phase in current and 
voltage It's just a matter of how MUCH of your power is 0 degrees 
phase shift and how MUCH of that VA is  + or - 90 degrees out of phase.  
If  ALL of the current is in phase with the voltage, then
the power factor is 1.0.   That is, if you lay them on top of each 
other, they will look the same on an oscilloscope if power factor = 1.0


It can get way more complicated that this too, but that's basically it.  
Feel free to add to this.


boB



power meters.


There is much more to it, with reactance, "real" and "imaginary" 
numbers?!, etc. but basically, we wrenches need to know that everybody 
wants  Power factor to be close to 1.
Obviously there isn't PF on DC, and it is my understanding that most 
inverters can operate at most power factors. 
Not 100% sure, but I think GT inverters would help not hurt the PF 
problem in most situations.


Correct me on any and all of this, Oh fellow wrenches,

R. Walters
Solarray.com
NABCEP # 04170442















On Jul 30, 2009, at 9:19 AM, boB Gudgel wrote:


Ron Young wrote:
Ok, so all seem to be in agreement more or less. How do I break it 
to British Columbia Hydro? :-|


I think they must be misunderstanding what they are asking for but 
the question is in the section for PV and on the same line as the 
total output in Kwh of the PV. Power Factor %


It was most likely just  a trick question.

You're gonna fool them, though !   :)


boB





I'll contact them and see where this goes but I don't fully 
understand what power factor is which will make it hard to argue my 
case. My understanding is that it is the difference between what the 
utility supplies to a residence vs. the actual loads being used by 
that residence expressed as a percentage. 
I came across the following course offering by SEI that discusses 
Power Factor with reference to PV:


POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS Presented By: 
Michael Smith of Alpine Management Systems 
 
This session will deal with power factor: What is power factor?  
What causes low power factor?  Why improve your power factor? This 
session will explain the role of power factor correction as it 
applies to solar installations. There are currently over 67,000 KVAR 
installations in 26 countries resulting in phenomenal energy savings 
with a corresponding reduction in greenhouse gas emissions. Session 
includes several KVAR installations and the resultant savings. 
http://www.solarenergy.org/workshops/docs/industry08_trainingdetails.pdf


Ron

On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:


There is no such thing as a power factor for DC or for panels.
 
..
Northern Arizona Wind & Sun - E

Re: [RE-wrenches] Power Factor

[R. Walters]

Power factor expresses the time difference  between voltage peak and  
current peak on each of their sine waves. If both current and voltage  
waves are "in time", (their wave peaks match up) power factor is 1.  
If one is ahead or behind the other, it's not. Think about an  
electric motor: we hit it with a voltage wave, and a fraction of a  
second later, it actually moves, and the current wave happens. There  
is a little lag there. Resistive loads like lights have very little  
lag, and big electric motors coming up to speed can have horrible PF.
There is much more to it, with reactance, "real" and "imaginary"  
numbers?!, etc. but basically, we wrenches need to know that  
everybody wants  Power factor to be close to 1.
Obviously there isn't PF on DC, and it is my understanding that most  
inverters can operate at most power factors.
Not 100% sure, but I think GT inverters would help not hurt the PF  
problem in most situations.


Correct me on any and all of this, Oh fellow wrenches,

R. Walters
Solarray.com
NABCEP # 04170442   



On Jul 30, 2009, at 9:19 AM, boB Gudgel wrote:


Ron Young wrote:
Ok, so all seem to be in agreement more or less. How do I break it  
to British Columbia Hydro? :-|


I think they must be misunderstanding what they are asking for but  
the question is in the section for PV and on the same line as the  
total output in Kwh of the PV. Power Factor %


It was most likely just  a trick question.

You're gonna fool them, though !   :)


boB





I'll contact them and see where this goes but I don't fully  
understand what power factor is which will make it hard to argue  
my case. My understanding is that it is the difference between  
what the utility supplies to a residence vs. the actual loads  
being used by that residence expressed as a percentage.
I came across the following course offering by SEI that discusses  
Power Factor with reference to PV:


POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS Presented By:  
Michael Smith of Alpine Management Systems


This session will deal with power factor: What is power factor?   
What causes low power factor?  Why improve your power factor? This  
session will explain the role of power factor correction as it  
applies to solar installations. There are currently over 67,000  
KVAR installations in 26 countries resulting in phenomenal energy  
savings with a corresponding reduction in greenhouse gas  
emissions. Session includes several KVAR installations and the  
resultant savings. http://www.solarenergy.org/workshops/docs/ 
industry08_trainingdetails.pdf


Ron

On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:


There is no such thing as a power factor for DC or for panels.
 ... 
...

Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
 
..


- Original Message -
*From:* Ron Young 
*To:* RE-wrenches 
*Sent:* Wednesday, July 29, 2009 5:45 PM
*Subject:* [RE-wrenches] Power Factor

Can anyone point me in the direction to find the power factor  
for

Sanyo HIT N 205 panels? The utility is requesting it on a net
metering interconnection application.
Ron Young
earthRight Products - Solareagle.com


 
 



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Re: [RE-wrenches] Power Factor

[David Brearley]

Ron,

Here is a definition for Power Factor that we used in our String Inverter
guide in SP1.1:

POWER FACTOR AT RATED OUTPUT
Definition: The ratio of true power to apparent power in the inverter ac
output circuit at its rated power.
Importance: True power is measured in units of watts and describes the
ability to do useful work. Apparent power includes both work-producing power
and reactive power measured in volt-amperes. Power factor is a comparison of
watts to volt-amperes or real power to apparent power in an ac circuit. If
the power factor in a circuit is 1.0, then all of the power generated is
available to do useful work.

The point is that you can describe the power factor for an inverter‹it
approaches unity (see the Table in SP1.1)‹but this does not apply for PV
modules. You can simply write ³NA² in the space provided. If they ask why,
the simplest explanation it that PV modules are part of a DC circuit and
power factor applies to AC circuits. It¹s not at all uncommon for
interconnection documents to request information that is not applicable to
PV systems.

Best,

David Brearley, Senior Technical Editor
SolarPro magazine 
NABCEP Certified PV Installer 
david.brear...@solarprofessional.com
Direct: 541.261.6545
Fax:  541.512.0343

Visit our Web site at solarprofessional.com

(Sample copy available for download at: solarprofessional.com/sample)


On 7/30/09 2:00 PM, "Ron Young"  wrote:

> Ok, so all seem to be in agreement more or less. How do I break it to British
> Columbia Hydro? :-|
> 
> I think they must be misunderstanding what they are asking for but the
> question is in the section for PV and on the same line as the total output in
> Kwh of the PV. Power Factor %
> 
> I'll contact them and see where this goes but I don't fully understand what
> power factor is which will make it hard to argue my case. My understanding is
> that it is the difference between what the utility supplies to a residence vs.
> the actual loads being used by that residence expressed as a percentage.
> 
> I came across the following course offering by SEI that discusses Power Factor
> with reference to PV:
> 
> POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS
> Presented By: Michael Smith of Alpine Management Systems
>  
> This session will deal with power factor: What is power factor?  What causes
> low power factor?  Why improve
> your power factor? This session will explain the role of power factor
> correction as it applies to solar installations.
> There are currently over 67,000 KVAR installations in 26 countries resulting
> in phenomenal energy savings with
> a corresponding reduction in greenhouse gas emissions. Session includes
> several KVAR installations and the
> resultant savings.
> http://www.solarenergy.org/workshops/docs/industry08_trainingdetails.pdf
> 
> Ron
> 
> On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:
> 
>> There is no such thing as a power factor for DC or for panels.
>>  
>> .
>> .
>> Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
>> Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
>> .
>> .
>>> - Original Message -
>>> From: Ron Young 
>>> To: RE-wrenches 
>>> Sent: Wednesday, July 29, 2009 5:45 PM
>>> Subject: [RE-wrenches] Power Factor
>>> 
>>> Can anyone point me in the direction to find the power factor for Sanyo HIT
>>> N 205 panels? The utility is requesting it on a net metering interconnection
>>> application.  
>>> 
>>> Ron Young
>>> earthRight Products - Solareagle.com
>>> 
>>> 
>>> 
>>> 
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Re: [RE-wrenches] Power Factor

[boB Gudgel]

Ron Young wrote:
Ok, so all seem to be in agreement more or less. How do I break it to 
British Columbia Hydro? :-|


I think they must be misunderstanding what they are asking for but the 
question is in the section for PV and on the same line as the total 
output in Kwh of the PV. Power Factor %


It was most likely just  a trick question.

You're gonna fool them, though !   :)


boB





I'll contact them and see where this goes but I don't fully understand 
what power factor is which will make it hard to argue my case. My 
understanding is that it is the difference between what the utility 
supplies to a residence vs. the actual loads being used by that 
residence expressed as a percentage. 

I came across the following course offering by SEI that discusses 
Power Factor with reference to PV:


POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS 
Presented By: Michael Smith of Alpine Management Systems 

 

This session will deal with power factor: What is power factor?  What 
causes low power factor?  Why improve 
your power factor? This session will explain the role of power factor 
correction as it applies to solar installations. 
There are currently over 67,000 KVAR installations in 26 countries 
resulting in phenomenal energy savings with 
a corresponding reduction in greenhouse gas emissions. Session 
includes several KVAR installations and the 
resultant savings. 
http://www.solarenergy.org/workshops/docs/industry08_trainingdetails.pdf


Ron

On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:


There is no such thing as a power factor for DC or for panels.
 
..

Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
..

- Original Message -
*From:* Ron Young 
*To:* RE-wrenches 
*Sent:* Wednesday, July 29, 2009 5:45 PM
*Subject:* [RE-wrenches] Power Factor

Can anyone point me in the direction to find the power factor for
Sanyo HIT N 205 panels? The utility is requesting it on a net
metering interconnection application.  


Ron Young
earthRight Products - Solareagle.com




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Re: [RE-wrenches] Power Factor

[Ron Young]

Ok, so all seem to be in agreement more or less. How do I break it to  
British Columbia Hydro? :-|


I think they must be misunderstanding what they are asking for but the  
question is in the section for PV and on the same line as the total  
output in Kwh of the PV. Power Factor %


I'll contact them and see where this goes but I don't fully understand  
what power factor is which will make it hard to argue my case. My  
understanding is that it is the difference between what the utility  
supplies to a residence vs. the actual loads being used by that  
residence expressed as a percentage.


I came across the following course offering by SEI that discusses  
Power Factor with reference to PV:


POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS
Presented By: Michael Smith of Alpine Management Systems

This session will deal with power factor: What is power factor?  What  
causes low power factor?  Why improve
your power factor? This session will explain the role of power factor  
correction as it applies to solar installations.
There are currently over 67,000 KVAR installations in 26 countries  
resulting in phenomenal energy savings with
a corresponding reduction in greenhouse gas emissions. Session  
includes several KVAR installations and the

resultant savings.
http://www.solarenergy.org/workshops/docs/industry08_trainingdetails.pdf

Ron

On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:


There is no such thing as a power factor for DC or for panels.

..
Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
..
- Original Message -
From: Ron Young
To: RE-wrenches
Sent: Wednesday, July 29, 2009 5:45 PM
Subject: [RE-wrenches] Power Factor

Can anyone point me in the direction to find the power factor for  
Sanyo HIT N 205 panels? The utility is requesting it on a net  
metering interconnection application.


Ron Young
earthRight Products - Solareagle.com



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Re: [RE-wrenches] Power Factor

[Wind-sun.com]

There is no such thing as a power factor for DC or for panels.

..
Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
..
  - Original Message - 
  From: Ron Young 
  To: RE-wrenches 
  Sent: Wednesday, July 29, 2009 5:45 PM
  Subject: [RE-wrenches] Power Factor


  Can anyone point me in the direction to find the power factor for Sanyo HIT N 
205 panels? The utility is requesting it on a net metering interconnection 
application.  


  Ron Young
  earthRight Products - Solareagle.com




--


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Re: [RE-wrenches] Power Factor

[Darryl Thayer]

HI The power factor is set by the inverter.  The modules are unity as there are 
DC.  but the inverter is very close to unity.  The couple of times I tried to 
measure power factor I got Unity.  But I would think the load may affect the 
inverter power factor.
Darryl 

--- On Wed, 7/29/09, Ron Young  wrote:

> From: Ron Young 
> Subject: [RE-wrenches] Power Factor
> To: "RE-wrenches" 
> Date: Wednesday, July 29, 2009, 7:45 PM
> Can anyone point me in the
> direction to find the power factor for Sanyo HIT N 205
> panels? The utility is requesting it on a net metering
> interconnection application.  
> Ron YoungearthRight Products -
> Solareagle.com
> 
> -Inline Attachment Follows-
> 
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> 


  
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Re: [RE-wrenches] Power Factor

[toddcory]

Power factor on DC? As far as I know, power factor / vars is an AC phenomena 
where current and voltage are out of phase.

Todd

On Wednesday, July 29, 2009 5:45pm, "Ron Young"  
said:

Can anyone point me in the direction to find the power factor for Sanyo HIT N 
205 panels? The utility is requesting it on a net metering interconnection 
application.  


Ron Young

earthRight Products - Solareagle.com

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Re: [RE-wrenches] power factor meter

[Matt Lafferty]

Hi Jay,

Take a look at the Fluke 125 Power Scope. It's about $1500. It looks like a
pretty sweet meter. I think it will do what you're looking for.
Multi-channel DVOM + AC Power + Power Factor + More. The clamp doesn't do DC
amps, so that's a bummer.

For higher-end things like this, I'm generally not afraid of used Fluke
gear. Unless it's really old and beat up, you can get it factory serviced
and calibrated pretty easily. (I've taken in 15 year old meters for factory
calibration at no charge. Twice I've even gotten new leads back with the
meter. Can't beat that! Other times I've paid a small charge for the
service. Never quite have figured out the formula. I think it has to do with
whether or not you bring donuts to the counter-man when you drop it off...)

Although not a true "o-scope", an old Fluke 41 or 43 Power Quality Analyzer
will do lots for you, including waveforms, AC Power & Power Factor,
Harmonics, Logging, VARS, etc. I believe these have both been replaced with
"new and improved" more expensive models, but you can still find them in
fine shape on Ebay and sometimes Craigslist. The 43 replaced the 41...
Better software, logging, and a few more features. I used to use both all
the time and they are great for field and shop work. Given my choice of the
two, I'd go with the 43. If I saw a 41 in good shape for under $500, I'd
grab it without batting an eye. I might blink a couple times at $750. These
meters don't do DC amps by the way. (If you are going to buy these meters
used, make sure you get the battery, charger, optical cable, and current
clamps with them at a mimimum! They originally came with some voltage leads
and clips and a case, too, but those can be replaced pretty cheap.) 

Although probably not kosher with certain list lurkers, you will have to
make up what I call a "3-way resistor bob" to do 3-Phase power & pf on a
3-wire system. If you're gonna do this kind of testing, make sure you use
resistors with high enough ohm & watt ratings. If you don't, it makes a
really loud BANG when it lets go and takes the sub-main with it...
Particularly embarrassing when you are on the 7th floor of a high-rise under
construction and half the power on the floor goes out during shakedown and
you thought you'd be a smart alec and wear a pink hardhat that day. It's a
long walk down to the basement to reset the breaker and nobody wants to ride
the elevator back up with a guy wearing a pink hardhat! (Yes, it really
happened, and yes, I still have the pink hardhat...) If you get this far,
I'd be happy to tell you (offlist) how to make up a 3-way resistor bob that
shouldn't go bang. 

The 43B info is here:
http://www.testequipmentdepot.com/fluke/powermeter/43b.htm  They want $2,330
for it new. I paid $2,700 for one 7 or 8 years ago. 

There are also a lot of pawn shops in my neighborhood that have some pretty
nice equipment from time to time. Let me know off list if you're interested
and I'd be happy to take a walk and see if there are any good deals on
high-end test equipment. (Open offer to Wrenches in general)

Another place to watch for high-end or utility grade test and data logging
gear is the surplus sale lists for utilities. These are also good sources
for other specialty gear that we don't use "every day" but is nice to have
and can make you some money. Underground locating equipment, large crimpers
& cable-splicing equipment, etc. I'm keeping my eyes open for a nice thermal
imaging camera, personally.

I've seen some deals that I wish I had a good excuse to take advantage of.
Momma says there are too many toys in my hammock. She wants to use the
thermal imaging camera herself, so that one is OK. Funny thing that
double-standard. Most utilities require you to register for their list so
you can bid and so they can notify you when stuff that matches what you sign
up for comes up.
 
PG&E is here:
http://www.pge.com/b2b/purchasing/buyingfrompge/investmentrecovery/ (nothing
really interesting this month unless you want a bunch of 6'ID concrete lined
steel pipe...)
SMUD is here:
https://usage.smud.org/EBSSExt/Default.aspx?SolDisplayType=BroadClass&SolBro
adClass=Surplus  (Currently no surplus sales pending)

Hope this is helpful to anyone that might be in the hunt for some of this
specialty gear.

Be safe!

Matt Lafferty
gilliga...@gmail.com

Brother Jay says:

I'm looking to upgrade my meter selection.

I'm looking for a powerfactor meter and oscilloscope  to better help in
diagnostics of inverter/generator issues.

I've seen a pretty inexpensive hand held oscilloscope from Velleman  # HPS10
for $135, but its not a power factor rated.

Any other suggestions?

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Re: [RE-wrenches] power factor meter

[Marv Dargatz]

I'd suggest a differential voltage probe and a current probe with a two 
channel scope.  Observe both waveforms simultaneously.  Phase shift 
(PF), amplitude, waveshape, harmonics, etc all at one time.  Most 
digital scopes you can store the waveforms, download them to your 
computer, or just take a photo with your digital camera.


Take a look at BitScope.  www.bitscope.com

See Ya!

Marv
Enphase Energy
707 763-4784 x7016

jay peltz wrote:

Hi All,

I'm looking to upgrade my meter selection.

I'm looking for a powerfactor meter and oscilloscope  to better help in 
diagnostics of inverter/generator issues.


I've seen a pretty inexpensive hand held oscilloscope from Velleman  # 
HPS10 for $135, but its not a power factor rated.


Any other suggestions?

thanks,

jay

peltz power



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