Your typical home meter measures only real power consumed.

 

There is no such thing as "reactive power being delivered to you". Any
reactive power that you may be concerned with will originate on your side of
the meter at the load. You really don't care about it there either as long
as the extra current does not cause excess resistive loss in your wires
going to the meter.

 

You could hang a large capacitor across one of your outlets and draw say 20
amps of current and the power meter would barely move. The only power that
would be consumed would be from any resistive drop in the wire between your
capacitor and the meter and any losses in the capacitor.

 

The power company usually cares about large amounts of reactive power as it
shows up to them as additional line loss.

 

73

Gary K4

FMX

 

  _____  

From: [email protected]
[mailto:[email protected]] On Behalf Of [email protected]
Sent: Monday, February 09, 2009 11:39 AM
To: [email protected]
Subject: Re: [Repeater-Builder] OT Power Factor

 

Very interesting subject.  People don't seem to be concerned about what kind
of energy they are receiving from electric power company suppliers.  I've
asked previously for information about what people get in their homes and
repeater sites with only one response telling me taps are available to solve
a high or low problem.  Do phase shift capacitors have an effect on our home
our test equipment, repeaters? The AC specs here are 115.2 - 124.8. A
calibrated NBS Fluke 77 reads consistently on the high end, and frequently
up as high as 128.  The power company engineer says they can do nothing
about it, that taps do not exist anywhere in the system  to lower the line
voltage. Only phase shift capacitors. Our older test equipment designed
around a 115 volt line plus AC motors, power transformers can have a problem
with saturation.  On a room to room/ garage/ shop investigation how many
transformers, motors are in your dweling? Those big honker 30 amp or higher
power supplies on repeaters going up in smoke. What's in your wallet....I
mean your electric service line?

Gary    K2UQ

 

 

In a message dated 2/9/2009 7:30:24 A.M. Eastern Standard Time,
[email protected] writes:

Depends. Some customers are metered for reactive demand. It would matter
then.

 

Chuck

WB2EDV

----- Original Message ----- 

From: Thomas Oliver <mailto:[email protected]>  

To: repeater-builder@ <mailto:[email protected]>
yahoogroups.com 

Sent: Monday, February 09, 2009 2:43 AM

Subject: [Repeater-Builder] OT Power Factor

 

Question for any electrical engineers out there.

 

Are the meters on the side of buildings metering real power or apparent
power?

 

Is power factor correction worth doing if the power company is not dinging
the customer for low power factor?

 

This article http://powerelectro
<http://powerelectronics.com/power_management/motor_power_management/705PET2
3.pdf> nics.com/power_management/motor_power_management/705PET23.pdf  talks
about residential power factor correction and my conclusion (from this
article) is the savings would never be recouped. 

 

Second conclusion is the only benefit with correction is the wires between
the source and load don't heat up as much. What about the wires in the motor
or transformer? do they also heat less? I would think so.

 

Third conclusion is by correcting power factor you are helping the utility
company more than yourself because these phase differences "standing waves"
exist all the way back to the power generation source therefore the utility
lines have more loss due to their greater length than the customers building
wiring has.

 

The reason I am researching this is a customer of mine has roughly 50 hp of
total motors in his shop and wanted to know if he could save 30% on his
electric bill like some salesman of power factor correction black boxes told
him he could.

 

I realize I am going to have to look at his energy bill to see if there is a
charge for low power factor and maybe call the utility company to see if he
will get a lower rate if he adds PFC devices

 

 

tom

 

 

 

(\__/) ... 

(='.'=) 

(")_(")

 

 


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