Re: AC Power Primer?

[Doug McKean]

From: 
>
> Another potential problem I see with calling both a phase-to-phase
> connection and a phase-to-neutral connection, "single-phase" is that
it
> presumes that all power supplies can be connected either way.  What
if a
> vendor designs a system in which the power supply is changed many
times over
> the years?  Can you be absolutely, 100% sure that any power supply
that you,
> or your successor, select will work with a phase-to-phase
connection?  Would
> you bet your reputation on it?  Would you bet your job on it?

Uh, yes - I have many times and do with the products I've
worked on.  That's part of my job responsibility.

My original statement which may have been lost in translation
was the following -  *IF* you can connect either as input, you
have a single phase system, AFAIC.

Your examples are obviously valid if those are the issues at
hand.  But, they are outside my point and do not contradict
what I originally said.  If however these issues are surprises
in the course of someone's job, then of course there's
reason for concern.

Regards, Doug McKean



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RE: AC Power Primer?

[Scott Lacey]

Rick, and group members,

I thought that I would weigh in with an opinion on this one. The definition
of phase should be determined by the requirements of the equipment. If the
equipment only requires single phase power, regardless of voltage, then that
is what should be specified. It does not matter if this single phase is
derived from a three phase source, it is still single phase.

One way to determine this is to ask yourself if the equipment could be
powered from a single phase electronic ac source. In my experience true two
phase equipment is extremely rare. Instead, what we usually find are racks
of equipment intended to be supplied from split phase (such as the typical
U.S. residential service). This is because the rack either contains a mix of
120V and 240V equipment, or the 120V equipment draws too much current for a
single circuit and must be split into two groups. None of these setups
actually require two phases of the same source and could easily be rewired
to operate from completely separate circuits.

If anyone is still confused, here is some (greatly simplified) background on
electrical power generation. Single phase alternators (often mistakenly
called generators) produce a single sinusoidal cycle for each revolution of
the input shaft. Frequency is determined by rotational speed. If an
additional connection is made at the midpoint of the winding the alternator
becomes a split phase type such as the 120V/240V types commonly sold as
portable power sources.

Three phase alternators have additional windings that each produce a single
sinusoidal cycle for every revolution of the input shaft. These waveforms
are staggered in time so that the peaks do not coincide with each other.
This is the most efficient way to generate electrical power. This is why
power companies use them.

Automobile alternators are also three phase. The outputs are rectified by
diode pairs to produce a pulsating dc output. The battery acts as a filter.
If an oscilloscope lead is placed right at the alternator terminals a slight
trace of the waveform can be seen. It is possible to detect "blown" diodes
that way.

Scott Lacey

-Original Message-
From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf
Of rbus...@es.com
Sent: Wednesday, May 02, 2001 4:31 PM
To: emc-p...@majordomo.ieee.org
Subject: AC Power Primer?



I am in the process of assisting our publications group with documenting an
ac power configuration. As simple as this sounds, it turns out there are
varying opinions in our engineering group regarding the naming convention
for input power, in particular single phase verses two phase.

We all probably agree that a phase to neutral connection is single phase and
devices that use all thee phases, whether they are 208V 60Hz or 400V 50Hz,
are truly three phase. The discussion heats up when you are talking about a
phase to phase connection on a three phase distribution (208 or 400V). Is
this called single phase or two phase? It has been suggested that in the
European community it is called two phase, while in the U.S. we call it
single phase.  I am looking for opinions or discussion on this issue.

On a related note in the U.S. we have 240V 60Hz (two 120V drops) coming into
our into our homes. This is provided by a transformer with a center taped
winding. On the outside legs of the transformer we have 240V but between
either outside leg and neutral (center tap) we have 120V. I would call this
a single phase system with two additive (in phase) 120V windings. Again
others have called this two phase.

My apologies to the group if this is a stupid question. Its just one of
those nagging questions.

Rick Busche
Evans & Sutherland
Salt Lake City, Utah

rbus...@es.com

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RE: AC Power Primer?

[Richardson, William G]

The important thing to note is that a good amount of the utility load is not
constant power.  It is light bulbs, toasters, coffeemakers, hairdryers and
electric heaters and so on. So lowering the voltage 10 % is the first step -
the so-called brown-outs.  Power is a square function, so the new power is
then 90% times 90% or only 81% of the original load. 

Bill Richardson 

-Original Message-
From: Ravinder Ajmani [mailto:ajm...@us.ibm.com]
Sent: Friday, May 04, 2001 12:28 PM
To: emc-p...@ieee.org
Subject: RE: AC Power Primer?




Can someone explain to me how reducing the voltage will lower the power
consumption, if the load is kept constant.  On the contrary, this should
cause an increase in consumption because higher current means increased
copper losses in the wiring.  This is the reason why power distribution is
done at very high voltage levels.

Regards, Ravinder
PCB Development and Design Department
IBM Corporation
Email: ajm...@us.ibm.com
***
Always do right.  This will gratify some people and astonish the rest.
. Mark Twain


Hans Mellberg @ieee.org on 05/04/2001 09:04:41 AM

Please respond to Hans Mellberg 

Sent by:  owner-emc-p...@ieee.org


To:   "Nerad, DarenHS-SNS" , "'Price, Ed'"
  , "'mkel...@es.com'" ,
  emc-p...@ieee.org
cc:
Subject:  RE: AC Power Primer?




Daren, you bring up an interesting point. California's energy woes could
possibly be
band-aid if the voltage was reduced 10%. (maybe that is too big of a
management
issue, does anyone know?) Assuming that a large percentage of the users
don't have
switcher regulators then that would equate to a 5-9% reduction in energy
consumption
hence reducing California's power problems significantly till more power
plants are
built. That might lower the spot market price!


--- "Nerad, DarenHS-SNS"  wrote:
>
> It all boils down to $$$s!
> Notice you don't see 110 V on the lines, probably not even 115 or 117 but
as
> close to 120V as they can keep it (except for you folks in CA, then this
is
> a digital thing, HA!).
>
> WHY?
>
> You consume more Watts if the V is greater!
>
> Check your wall outlet, what does it read?
>
> IT would be interesting to use this forum to do a quick & dirty survey.
> Granted we can only hit where engineers feel like making measurements, &
> when they do, but it would be interesting...
>
> Daren A. Nerad
> EMC Engineer
>


=
Best Regards
Hans Mellberg
Regulatory Compliance Consultant
and Design Services
By the Pacific Coast next to Silicon Valley
Santa Cruz, CA, USA
408-507-9694

__
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Re: Trading Standards UK

[John Woodgate]

<3.0.6.32.20010504170055.00847...@mail.cinepower.com>, Enci
 inimitably wrote:
>In the UK, what scope does a Trading Standards Officer have with regard
>to inspecting compliance with European Directives?  (LVD & EMC)
>
>As I understand it, they can inspect the evidence to support a DoC and
>samples of equipment have to be made available for them if they wish.
>Can they inspect any equipment and related documentation manufactured and
>made available for sale, professional and non-professional equipment,
>bearing CE marking?

Yes.

>Are they entitled to inspect the manufacturing process?

You would be unwise to refuse. I can't say more than that on a public
forum, lest I give some people fresh ideas.
-- 
Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839
Fax +44 (0)1268 777124. http://www.jmwa.demon.co.uk Why not call a vertically-
applied manulo-pedally-operated quasi-planar chernozem-penetrating and 
excavating implement a SPADE?

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RE: Back to batteries

[WOODS]

These batteries are not sealed against the release of hydrogen gas that is
generated during the charging process. I once tested for the concentration
of gas in the battery area in a cash drawer enclosure of an electronic cash
register and found a very high level - less than what is required for
ignition, but still high enough that we added vent holes in order to prevent
flying drawers - that would be a surprise for the clerk!

--
From:  Gary McInturff [SMTP:gary.mcintu...@worldwidepackets.com]
Sent:  Friday, May 04, 2001 1:59 PM
To:  EMC-PSTC (E-mail)
Subject:  Back to batteries


Do sealed Gel-lead acid batteries really require vented
enclosures?
If so why, they don't vent like the "liquid" lead acid batteries do
they?
Thanks - 
Gary

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RE: UL 1419 Earth Leakage

[Andrews, Kurt]

Duncan,

Here is the definition of "Direct Plug-in Equipment" from the EN60950
standard-"Equipment that is intended to be used without a power supply cord;
the mains plug forms an integral part of the equipment enclosure so that the
weight of the equipment is taken by the socket-outlet"

These are what I refer to as wall transformers. They are small (at most
about 3 x 4 x 2") units that plug in the wall and typically have a low
voltage DC output for things like printers, portable radios, etc.

Even if your unit was considered "Direct Plug-in Equipment" that part of the
test would not be applicable since your equipment is Class I and therefore
by definition has an equipment grounding conductor.

I do not know the rationale behind the S1 requirement.

I hope this answers at least some of your questions.

Kurt Andrews
Compliance Engineer

Tracewell Systems, Inc.
567 Enterprise Drive
Westerville, Ohio 43081
voice:  614.846.6175
toll free:  800.848.4525
fax: 614.846.7791

http://www.tracewellsystems.com/  


-Original Message-
From:   duncan.ho...@snellwilcox.com
[SMTP:duncan.ho...@snellwilcox.com]
Sent:   Friday, May 04, 2001 12:18 PM
To: emc-p...@majordomo.ieee.org
Subject:UL 1419 Earth Leakage


Group,
Are there any group members who are familiar with the earth
leakage
requirements of UL1419 (Standard for Safety - Professional Audio and
Visual
equipment) in section 41.1

Our equipment is a detachable power cord connected, class 1
appliance rated at
100 -250 V. 

Section 41.1.9 of the standard clearly states that 'Switch S1 as
shown in figure
41.1 is used only for direct plug in power supply products that do
not employ an
equipment grounding conductor...'   (S1 acually open circuits the
neutral
conductor)

My three questions are:

-   Would they use S1 when leakage testing our type of equipment?
-   What is the definition of 'direct plug in' (it is not mentioned
in the
definitions section)
-   For 'direct plug in' equipment what is the reason for operating
this switch
i.e what is the rationale behind the provision of S1.

Any help or comments would be greatly recieved.

Many thanks in advance,

Duncan Hobbs, Product Safety Engineer
Snell and Wilcox Ltd.


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RE: AC Power Primer?

[mkelson]

It looks like California does run on reduced voltage.  See the following
URL, for instance:

 
http://www.world.std.com/~techbook/seec2_2.htm

It says:

2.2.2 North America

ANSI C84.1 "Electric Power Systems and Equipment - Voltage Ratings (60 Hz)
sets the preferred nominal voltage at 120V and allows a range of 114 - 126V
(240V nominal, range 228 - 252V). Equivalent Canadian spec is CAN3-C235.

Voltage at a 120 volt nominal single phase receptacle should be 110 to 125V
under normal conditions.

However, the California Public Utilities Commission has specified that the
service voltage shall be kept in the range 114-120V, with some exceptions.
This was done because some studies showed a reduction in energy consumption
at the lower voltages.

Max Kelson, Evans & Sutherland
---

To:   "Nerad, DarenHS-SNS" , "'Price, Ed'"
  , "'mkel...@es.com'" ,
  emc-p...@ieee.org
cc:
Subject:  RE: AC Power Primer?




Daren, you bring up an interesting point. California's energy woes could
possibly be
band-aid if the voltage was reduced 10%. (maybe that is too big of a
management
issue, does anyone know?) Assuming that a large percentage of the users
don't have
switcher regulators then that would equate to a 5-9% reduction in energy
consumption
hence reducing California's power problems significantly till more power
plants are
built. That might lower the spot market price!


--- "Nerad, DarenHS-SNS"  wrote:
>
> It all boils down to $$$s!
> Notice you don't see 110 V on the lines, probably not even 115 or 117 but
as
> close to 120V as they can keep it (except for you folks in CA, then this
is
> a digital thing, HA!).
>
> WHY?
>
> You consume more Watts if the V is greater!
>
> Check your wall outlet, what does it read?
>
> IT would be interesting to use this forum to do a quick & dirty survey.
> Granted we can only hit where engineers feel like making measurements, &
> when they do, but it would be interesting...
>
> Daren A. Nerad
> EMC Engineer
>


=
Best Regards
Hans Mellberg
Regulatory Compliance Consultant
and Design Services
By the Pacific Coast next to Silicon Valley
Santa Cruz, CA, USA
408-507-9694

__
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Yahoo! Auctions - buy the things you want at great prices
  http://auctions.yahoo.com/

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RE: Is 36-72VDC power supply input still valid?

[Gary McInturff]

Hopefully, one our European friends will have a better answer, but
my understanding was that in older (don't have a definition of older)
European telco you would find the batter stack with 60 V, rather than 48,
Then you had to worry about the charging voltage and step down power
supplies.
This could also be an old wives tale so I am also anxious to hear
this answer
Gary

-Original Message-
From: Denomme, Paul S. [mailto:paul.deno...@viasystems.com]
Sent: Friday, May 04, 2001 8:37 AM
To: "EMC-PSTC (E-mail)" <
Subject: Is 36-72VDC power supply input still valid?



I have recently had a discussion with someone who stated that people are no
longer specifying a 36-72V input, and that they are specifying 42-56V
because it is more standard for todays applications?  Does anyone know where
the 36-72V input requirement originated and where and when we still need to
design to the old specification of 36-72V?

Any input would be greatly appreciated.

Regards,

Paul S. Denomme
Viasystems



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Back to batteries

[Gary McInturff]

Do sealed Gel-lead acid batteries really require vented enclosures?
If so why, they don't vent like the "liquid" lead acid batteries do they?
Thanks - 
Gary

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Product Safety - Japan

[georgea]

The new Japan DENAN requirements are not completely clear,
and I know of no on-line source in English to clear up certain aspects.

For example, in the past, AC/DC adapters have required certification
and the application of the Dentori-T mark with cert. number.  However,
there was no mandatory Japan certification for most ITE end products,
e.g. the laser and inkjet printers we market.

The attached MS Word file refers to "specified products" (SP) and
"non-specified products" (NSP), and lists 19 product "categories".
However, it does not reveal if ITE might be included in categories 17
(electronic appliances) or 18 (other electronic apparatuses), or even
incuded at all as an SP or NSP product requiring certification.

George


(See attached file: Japan DENAN Scheme.doc)


Japan DENAN Scheme.doc
Description: Mac Word 3.0

RE: Is 36-72VDC power supply input still valid?

[David Spencer]

Hi Paul,
I am assuming that you are speaking about telecommunications switching
equipment.  The upper end of -72 volts supports -60V battery plant found in
a few German offices with (I believe) Siemens switches.  There is every
indication that these systems will not "spread" to other offices and global
standardization on a -48V battery plant will occur through attrition.  Many
companies start down the road of supporting -60V plant equipment until they
realize the additional cost involved in manufacturing/design of a system
with TNV2/Hazardous Secondary (depends who you talk to) input voltage.
Hope this answers your question.
Regards,
Dave Spencer
Oresis Communications

-Original Message-
From: Denomme, Paul S. [mailto:paul.deno...@viasystems.com]
Sent: Friday, May 04, 2001 8:37 AM
To: "EMC-PSTC (E-mail)" <
Subject: Is 36-72VDC power supply input still valid?



I have recently had a discussion with someone who stated that people are no
longer specifying a 36-72V input, and that they are specifying 42-56V
because it is more standard for todays applications?  Does anyone know where
the 36-72V input requirement originated and where and when we still need to
design to the old specification of 36-72V?

Any input would be greatly appreciated.

Regards,

Paul S. Denomme
Viasystems



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RE: AC Power Primer?

[Ravinder Ajmani]

Can someone explain to me how reducing the voltage will lower the power
consumption, if the load is kept constant.  On the contrary, this should
cause an increase in consumption because higher current means increased
copper losses in the wiring.  This is the reason why power distribution is
done at very high voltage levels.

Regards, Ravinder
PCB Development and Design Department
IBM Corporation
Email: ajm...@us.ibm.com
***
Always do right.  This will gratify some people and astonish the rest.
. Mark Twain


Hans Mellberg @ieee.org on 05/04/2001 09:04:41 AM

Please respond to Hans Mellberg 

Sent by:  owner-emc-p...@ieee.org


To:   "Nerad, DarenHS-SNS" , "'Price, Ed'"
  , "'mkel...@es.com'" ,
  emc-p...@ieee.org
cc:
Subject:  RE: AC Power Primer?




Daren, you bring up an interesting point. California's energy woes could
possibly be
band-aid if the voltage was reduced 10%. (maybe that is too big of a
management
issue, does anyone know?) Assuming that a large percentage of the users
don't have
switcher regulators then that would equate to a 5-9% reduction in energy
consumption
hence reducing California's power problems significantly till more power
plants are
built. That might lower the spot market price!


--- "Nerad, DarenHS-SNS"  wrote:
>
> It all boils down to $$$s!
> Notice you don't see 110 V on the lines, probably not even 115 or 117 but
as
> close to 120V as they can keep it (except for you folks in CA, then this
is
> a digital thing, HA!).
>
> WHY?
>
> You consume more Watts if the V is greater!
>
> Check your wall outlet, what does it read?
>
> IT would be interesting to use this forum to do a quick & dirty survey.
> Granted we can only hit where engineers feel like making measurements, &
> when they do, but it would be interesting...
>
> Daren A. Nerad
> EMC Engineer
>


=
Best Regards
Hans Mellberg
Regulatory Compliance Consultant
and Design Services
By the Pacific Coast next to Silicon Valley
Santa Cruz, CA, USA
408-507-9694

__
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UL 1419 Earth Leakage

[duncan . hobbs]

Group,
Are there any group members who are familiar with the earth leakage
requirements of UL1419 (Standard for Safety - Professional Audio and Visual
equipment) in section 41.1

Our equipment is a detachable power cord connected, class 1 appliance rated at
100 -250 V. 

Section 41.1.9 of the standard clearly states that 'Switch S1 as shown in figure
41.1 is used only for direct plug in power supply products that do not employ an
equipment grounding conductor...'   (S1 acually open circuits the neutral
conductor)

My three questions are:

-   Would they use S1 when leakage testing our type of equipment?
-   What is the definition of 'direct plug in' (it is not mentioned in the
definitions section)
-   For 'direct plug in' equipment what is the reason for operating this switch
i.e what is the rationale behind the provision of S1.

Any help or comments would be greatly recieved.

Many thanks in advance,

Duncan Hobbs, Product Safety Engineer
Snell and Wilcox Ltd.


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Trading Standards UK

[Enci]

In the UK, what scope does a Trading Standards Officer have with regard
to inspecting compliance with European Directives?  (LVD & EMC)

As I understand it, they can inspect the evidence to support a DoC and
samples of equipment have to be made available for them if they wish.
Can they inspect any equipment and related documentation manufactured and
made available for sale, professional and non-professional equipment,
bearing CE marking?
Are they entitled to inspect the manufacturing process?

I am curious and would appreciate any experiences or comments either on the
mailing list or off list.

Thank you, 
Enci.


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RE: AC Power Primer?

[Hans Mellberg]

Daren, you bring up an interesting point. California's energy woes could 
possibly be
band-aid if the voltage was reduced 10%. (maybe that is too big of a management
issue, does anyone know?) Assuming that a large percentage of the users don't 
have
switcher regulators then that would equate to a 5-9% reduction in energy 
consumption
hence reducing California's power problems significantly till more power plants 
are
built. That might lower the spot market price!


--- "Nerad, DarenHS-SNS"  wrote:
> 
> It all boils down to $$$s!
> Notice you don't see 110 V on the lines, probably not even 115 or 117 but as
> close to 120V as they can keep it (except for you folks in CA, then this is
> a digital thing, HA!).
> 
> WHY?
> 
> You consume more Watts if the V is greater!
> 
> Check your wall outlet, what does it read?
> 
> IT would be interesting to use this forum to do a quick & dirty survey.
> Granted we can only hit where engineers feel like making measurements, &
> when they do, but it would be interesting...
> 
> Daren A. Nerad
> EMC Engineer
> 


=
Best Regards
Hans Mellberg
Regulatory Compliance Consultant
and Design Services
By the Pacific Coast next to Silicon Valley
Santa Cruz, CA, USA
408-507-9694

__
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RE: AC Power Primer?

[Hans Mellberg]

The US 220 came from the days of single phase split winding transformers 
yielding
110 to Neutral. Not a three phase thing but, the "open-delta" two phase 
transformers
used in residential distribution, were two split winding transformers wound is a
three phase style with the third winding missing. It also provided splits for 
110V
and are truly a two phase system. But a matter of semantics. The open delta
transformer was a cost reduced virtual three phase!!!.

--- mkel...@es.com wrote:
> 
> Just out of curiosity, where does the designation "220V come from?  If you
> measure the potential difference between two phases of a three-phase system,
> you get 208V.  If you measure the difference between the two phases in a
> residential or light commercial area, you would probably get 240V.  
> 
> So, where does the term "220V" come from?
> 
> Thanks,
> 
> Max Kelson
> Evans & Sutherland



=
Best Regards
Hans Mellberg
Regulatory Compliance Consultant
and Design Services
By the Pacific Coast next to Silicon Valley
Santa Cruz, CA, USA
408-507-9694

__
Do You Yahoo!?
Yahoo! Auctions - buy the things you want at great prices
http://auctions.yahoo.com/

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Is 36-72VDC power supply input still valid?

[Denomme, Paul S.]

I have recently had a discussion with someone who stated that people are no
longer specifying a 36-72V input, and that they are specifying 42-56V
because it is more standard for todays applications?  Does anyone know where
the 36-72V input requirement originated and where and when we still need to
design to the old specification of 36-72V?

Any input would be greatly appreciated.

Regards,

Paul S. Denomme
Viasystems



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Re: Radiated emssions equipment to 10 GHz?

[Ken Javor]

The old standby is the HP8566, but it uses harmonic mixing above 2.5 GHz, 
which decreases sensitivity.  Then there is the HP8593 which also has
decreasing sensitivity above 6 GHz. The 8566 is obsolete, but readily
available.  Carnel  (to my knowledge) still makes the excellent EMI receiver
series NM-7, NM-17/27, NM 37/57, and NM-67, which beat any analyzer for
sensitivity, plus they are now HP-IB addressable and can be bought as part
of an integrated automated system. The NM-67 is the device tunable from 1 -
18 GHz (per my recollection).  And Rhode & Schwarz now tries to fill the
hole left by Agilent when they ceased to make full compliance EMI test
equipment.   They make a "receive-alyzer" that tunes to 26.5 GHz.

--
From: "David Gelfand" 
To: 
Subject: Radiated emssions equipment to 10 GHz?
List-Post: emc-pstc@listserv.ieee.org
Date: Fri, May 4, 2001, 8:06 AM


What receivers or spectrum analyzers are used for making radiated emissions
measurements to 10 GHz?

Best regards,

David.

David Gelfand
Regulatory Approvals
Memotec Communications Inc.

RE: AC Power Primer?

[mkelson]

>From the point of view of an electrician or a technician, I can understand,
to some extent, how one could consider a phase-to-phase connection as being
single phase.  From the point of view of a design engineer, however, there
would probably be some differences.  With a system that references neutral
you might only use one circuit breaker for instance and one of the wires
connected to the power supply would be blue.

There is also a potential problem in providing documentation for customers.
If a vendor's documentation specifies a single-phase connection and
indicates that the power supply is auto-ranging, a European customer would
assume that the product was plug and play compatible with European line
voltage.  When he plugged it in, however, the supply would fry with 400V,
phase-to-phase voltage across the inputs.  You could solve this problem, I
suppose, by sending the European customer a "true" single-phase system and
sending the American customer a "pseudo?" single-phase system.

For U.S. customers, you need to add a voltage specification to try to help
the him understand the requirements since some customers might expect that
the term single phase means a phase to neutral connection.  Many (most?)
manufacturer's might say "220 VAC, single-phase" to clarify things.  Now the
plot thickens even more since there is no such thing as "220 VAC" in the
U.S., unless the customer has some unusual facilities wiring.  Standard,
nominal voltages in the US for light-industrial installations are 208 and
120.  At this point, I wouldn't be surprised if the vendor were to get a
call from a customer asking: "Hey do you guys really know what you're
doing?".

Another potential problem I see with calling both a phase-to-phase
connection and a phase-to-neutral connection, "single-phase" is that it
presumes that all power supplies can be connected either way.  What if a
vendor designs a system in which the power supply is changed many times over
the years?  Can you be absolutely, 100% sure that any power supply that you,
or your successor, select will work with a phase-to-phase connection?  Would
you bet your reputation on it?  Would you bet your job on it?  What if the
guy that designed the power supply happened to hang a relatively low-voltage
capacitor from the neutral input to ground, for instance?

It's possible, I suppose, that a technician or electrician might be able to
use the same term to describe two different configurations.  A design
engineer cannot.

Max Kelson
Evans & Sutherland


-Original Message-
From: Doug McKean [mailto:dmck...@corp.auspex.com]
Sent: Thursday, May 03, 2001 7:30 PM
To: emc-p...@majordomo.ieee.org
Subject: Re: AC Power Primer?



In my experience, a system that gets its power from a power
supply which for input has either a transformer or a switcher
with a two port input across which is connected one hot line
and one neutral line or two hots out of phase from each other,
that system is a 'single phase' system.  Even though two phases
may be used as power input, the effectivity is to act as a single
phase input and can operate that way as well.

In other words, if you can plug and chug with no problems by
replacing an input consisting of two hots out of phase from each
other by a single phase hot/neutral input, then you've got a single
phase system.

It's effectively what the primary 'sees', one phase and that's what's
counts, AFAIC.

Regards, Doug McKean



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RE: EMC-PSTC List Archive Site

[UMBDENSTOCK]

New address:

http://www.cfont.com/

> --
> From: Peter G Schreiner III[SMTP:p...@sciatl.com]
> Reply To: Peter G Schreiner III
> Sent: Friday, May 04, 2001 9:09 AM
> To:   emc-p...@ieee.org
> Subject:  EMC-PSTC List Archive Site
> 
> 
> 
> Being new to the list, I would like to search the archives for answers to 
> questions that might have been addressed many times in the past.  I have 
> not been successful in my attempts to link to the archive site that was 
> provided in my introductory message after subscription to the 
> list.  http://www.rcic.com is what I believe I am supposed to contact.
> Any 
> assistance in gaining access to the list archives would certainly be 
> appreciated.
> 
> TIA,
> 
> Pete Schreiner
> 
> 
> ---
> This message is from the IEEE EMC Society Product Safety
> Technical Committee emc-pstc discussion list.
> 
> Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/
> 
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RE: DC/DC Convertor with BASIC INSULATION

[Goldstein, David]

SynQor
Lucent/Tyco
di/dt
Power One  

Hope that this helps

<
David B. Goldstein
Principal Manufacturing Engineer
Cratos Networks
313 Littleton Rd; Suite 20
Chelmsford, MA 01824
978-244-0068 ext. 150
FAX (978) 244-0618
dgoldst...@cratosnetworks.com



-Original Message-
From: Peter Merguerian [mailto:pmerguer...@itl.co.il]
Sent: Friday, May 04, 2001 4:55 AM
To: "EMC-PSTC (E-mail)" <
Subject: DC/DC Convertor with BASIC INSULATION



Dear All,

Does anyone have a list of manufacturers of Approved (UL Recognized/ TUV
Approved) 36-72V range dc/dc convertor with the following characteristics
and at least BASIC INSULATION between the input and output? The dc/dc
converor will be used for a telecom device intended for connection to a
Centralized DC source of supply.
3.3V/20A in Quarter Brick 
3.3V/10A in Quarter Brick 
2.5V/20A in Quarter Brick 
1.8V/40A in Half Brick 


PETER S. MERGUERIAN
Technical Director
I.T.L. (Product Testing) Ltd.
26 Hacharoshet St., POB 211
Or Yehuda 60251, Israel
Tel: 972-3-5339022  Fax: 972-3-5339019
Mobile: 972-54-838175






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<>

Mexico Radios

[Wismer, Sam]

Group,
I need some opinions on shipping radio devices to Mexico.  Information is
very difficult to get from the SCT directly and our distributors play down
the need for type approval, so I am having difficulties in getting a
straight answer to the legal way to ship product.

My understanding is:
- Type approval only issued to company in Mexico.  
- Type approved equipment can only be sold in Mexico by the type approval
holder. 

Here is the scenario I am faced with:

Company A has a radio type approved in Mexico by the SCT.  We intend to OEM
and integrate these radios into our products.  Company A also mfg's products
similar to ours and is our competitor on this level.  This radio is type
approved by with the SCT by Company A's distributor.  

Assuming my understanding above is correct, does that mean we have to ship
our terminals with the integrated radios to Company A's distributor, who is
our direct competitor?

Any help is appreciated.  Safety and EMI is understood so please limit
responses to radios only.  

Thanks Much,

~
Sam Wismer
Lead Regulatory Engineer/
Radio Approvals Engineer
LXE, Inc.
(770) 447-4224 Ext. 3654

Visit Our Website at:
http://www.ems-t.com

 <> 
<>

EMC-PSTC List Archive Site

[Peter G Schreiner III]

Being new to the list, I would like to search the archives for answers to 
questions that might have been addressed many times in the past.  I have 
not been successful in my attempts to link to the archive site that was 
provided in my introductory message after subscription to the 
list.  http://www.rcic.com is what I believe I am supposed to contact.  Any 
assistance in gaining access to the list archives would certainly be 
appreciated.


TIA,

Pete Schreiner


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Radiated emssions equipment to 10 GHz?

[David Gelfand]

What receivers or spectrum analyzers are used for making radiated emissions 
measurements to 10 GHz?

Best regards,

David.

David Gelfand 
Regulatory Approvals
Memotec Communications Inc.

DC/DC Convertor with BASIC INSULATION

[Peter Merguerian]

Dear All,

Does anyone have a list of manufacturers of Approved (UL Recognized/ TUV
Approved) 36-72V range dc/dc convertor with the following characteristics
and at least BASIC INSULATION between the input and output? The dc/dc
converor will be used for a telecom device intended for connection to a
Centralized DC source of supply.
3.3V/20A in Quarter Brick 
3.3V/10A in Quarter Brick 
2.5V/20A in Quarter Brick 
1.8V/40A in Half Brick 


PETER S. MERGUERIAN
Technical Director
I.T.L. (Product Testing) Ltd.
26 Hacharoshet St., POB 211
Or Yehuda 60251, Israel
Tel: 972-3-5339022  Fax: 972-3-5339019
Mobile: 972-54-838175






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Re: Measurement instruments that are installed into a PC

[John Woodgate]

, Chaplis,
Bob  wrote:
>Signametrics makes modular instruments that can be  installed into a PCI
>slot within a PC. Im familiar with only the DMM module at this time. This
>module is capable of measuring voltages to 330v, DC/AC currents to 2.5 a,
>Temperature, Resistance etc. Has anyone out there had experience with this
>type of a product and how it impacts the approval of the pc where you now
>are making a PC  a piece of test equipment? Do I need to submit the PC and
>module for retest as test equipment to the apropriate standard. Any help
>would be appreciated.

Where are you proposing to sell it? If it's in Europe, you are not
compelled to submit anything for 3rd party testing, but the PC and card,
taken as a whole, should meet EN61010-1. You do not have to apply this
standard to anything in the PC not affected by the presence or absence
of the card: EN60950 applies to that.
-- 
Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839
Fax +44 (0)1268 777124. http://www.jmwa.demon.co.uk Why not call a vertically-
applied manulo-pedally-operated quasi-planar chernozem-penetrating and 
excavating implement a SPADE?

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Re: EN60945 - Conducted emission

[John Woodgate]

<20010503173419.30021.qm...@www3.nameplanet.com>, am...@westin.org
inimitably wrote:
>>John Woodgate wrote:
>>According to which standard? Requirements are not identical in different
>>standards, sometimes for good reasons and sometimes for historical
>>reasons.
>>-- 
>
>Standard :EN60945 / IEC945. 
>Is conducted emission på DC power input port mandatory ?

This is a specialized standard, for marine electronic equipment. You
should buy it.
-- 
Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839
Fax +44 (0)1268 777124. http://www.jmwa.demon.co.uk Why not call a vertically-
applied manulo-pedally-operated quasi-planar chernozem-penetrating and 
excavating implement a SPADE?

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Re: AC Power Primer?

[John Woodgate]

, Price, Ed
 wrote:
>The nominal 208 Vrms value exists
>from any phase-to-phase pair. The voltage from any phase to neutral is 115
>Vrms. 

208/sqrt(3) = 120, not 115. 110 V was around in the 1920s, AIUI. By WW2,
the voltage had already crept up to 115 V or thereabouts, witness the
tubes like 117N7GT, with 117 V heaters.
-- 
Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839
Fax +44 (0)1268 777124. http://www.jmwa.demon.co.uk Why not call a vertically-
applied manulo-pedally-operated quasi-planar chernozem-penetrating and 
excavating implement a SPADE?

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Re: AC Power Primer?

[CDUPRES]

Hi Brian.

<< Just to add a little more fuel to the flames! We
 supplied an Instrument to a well known semiconductor Manufacturer in Oregon
 which was powered from two 220 volt phases. I marked the rating plate as 220
 volt one phase as has been suggested. However the local inspector made us
 change it to 220 volt two phase. So what is the correct definition.   >>

I was always encouraged to describe a supply by how many phases were not 
earthed, and a device by how many phases it used.  In that context there is 
no such thing as a two phase device, at least not in the UK, as a two phase 
device would have three wires and the third phase is already there as the 
algebraic sum of the two phases.

In the UK the distribution system is Earthed Neutral 3 phase equal star.  In 
the USA and many other places there are all sorts of systems, e.g. open delta 
- earthed centre tap one phase, close delta earthed on phase, two phase 
earthed centre tap...  the list is long..

In the UK, we use 1 phase and neutral, or three phases with or without 
neutral.   Industrial systems use 2 phases, usually for control transformers 
which are single phase devices running at 415V, as there is no neutral.  In 
the UK neutral and Earth are tied together at the distribution room, but NO 
current is permitted in the local Protective Earth conductor or the 30mA 
RCD's trip.

I think your local inspector was probably OK in asking for the label to say 
Two Phase, as it was a Single phase device connected to Two phases.

Sound reasonable?

Chris Dupres
Surrey, UK.

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Re: AC Power Primer?

[Doug McKean]

In my experience, a system that gets its power from a power
supply which for input has either a transformer or a switcher
with a two port input across which is connected one hot line
and one neutral line or two hots out of phase from each other,
that system is a 'single phase' system.  Even though two phases
may be used as power input, the effectivity is to act as a single
phase input and can operate that way as well.

In other words, if you can plug and chug with no problems by
replacing an input consisting of two hots out of phase from each
other by a single phase hot/neutral input, then you've got a single
phase system.

It's effectively what the primary 'sees', one phase and that's what's
counts, AFAIC.

Regards, Doug McKean



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Re: quiet support equipment

[mike harris]

Hi George,

When I was starting the same kind of search 2 years ago, I asked Dell's EMC
dept. for a suggestion on their quietest desktop pc.  The PC was & is very
quiet, but the video card made some monitors scream at highest rated
resolution & refresh rate. Other video cards will have vastly different
effects on the monitors. This synergism may or may not be an issue for you,
but you may want to ask Dell for suggestions on monitors as well.

Mike Harris/Teccom Co.

-Original Message-
From: George Stults 
To: 'emc-p...@majordomo.ieee.org' 
List-Post: emc-pstc@listserv.ieee.org
Date: Tuesday, May 01, 2001 3:58 PM
Subject: quiet support equipment


>
>Hello All,
>
>I'm testing a Class B computer peripheral and looking for recommendations
as
>to
> 'quiet' support equipment that I can obtain in the USA.
>
>I'm looking for an Intel based computer;  laptop or table top,
>ethernet card (NIC)
>monitor.
>10/100 base-t hub
>printer
>
>So far, I plan to go with a  Dell Dimension 4100 pc, with a 3Com ethernet
>card,
>and a Sony Multisync monitor, and either a Cisco or 3Com Hub.
>I don't have any clue about the printer yet.
>
>Does anyone have any other recommendations?
>Thanks in advance for any info or advice.
>
>
>George Stults
>WatchGuard Technologies Inc.
>
>
>---
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>Technical Committee emc-pstc discussion list.
>
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>
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>
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>http://www.rcic.com/  click on "Virtual Conference Hall,"
>


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RE: AC Power Primer?

[Nerad, Daren HS-SNS]

All right...

I had heard this from a former nuclear power plant worker (NOT Homer
Simpson, opposite end of intelligence spectrum).

Passed it on as a bit of cynical (realist?) humor...  
(the caffeine in the Mountain Dew made me get an early jump on "Friday
Funnies")

Daren A. Nerad
EMC Engineer
815.226.6123


-Original Message-
From: mkel...@es.com [mailto:mkel...@es.com]
Sent: Thursday, May 03, 2001 4:57 PM
To: emc-p...@ieee.org
Subject: RE: AC Power Primer?



Look at the bright side.  With a higher voltage, your wife can buy more
kitchen appliances and put more of them on the same circuit :)

-Original Message-
From: Nerad, Daren HS-SNS [mailto:daren.ne...@hs.utc.com]
Sent: Thursday, May 03, 2001 2:32 PM
To: 'Price, Ed'; 'mkel...@es.com'; emc-p...@ieee.org
Subject: RE: AC Power Primer?



It all boils down to $$$s!
Notice you don't see 110 V on the lines, probably not even 115 or 117 but as
close to 120V as they can keep it (except for you folks in CA, then this is
a digital thing, HA!).

WHY?

You consume more Watts if the V is greater!

Check your wall outlet, what does it read?

IT would be interesting to use this forum to do a quick & dirty survey.
Granted we can only hit where engineers feel like making measurements, &
when they do, but it would be interesting...

Daren A. Nerad
EMC Engineer



-Original Message-
From: Price, Ed [mailto:ed.pr...@cubic.com]
Sent: Thursday, May 03, 2001 1:05 PM
To: 'mkel...@es.com'; emc-p...@ieee.org
Subject: RE: AC Power Primer?



>-Original Message-
>From: mkel...@es.com [mailto:mkel...@es.com]
>Sent: Thursday, May 03, 2001 8:22 AM
>To: brian.harl...@vgscientific.com; emc-p...@ieee.org
>Subject: RE: AC Power Primer?
>
>
>
>Just out of curiosity, where does the designation "220V come 
>from?  If you
>measure the potential difference between two phases of a 
>three-phase system,
>you get 208V.  If you measure the difference between the two 
>phases in a
>residential or light commercial area, you would probably get 240V.  
>
>So, where does the term "220V" come from?
>
>Thanks,
>
>Max Kelson
>Evans & Sutherland
>

[SNIP]

Max:


There's many more expert than I on this subject, but

The USA has several "standard" powers available to non-heavy industrial
consumers.

A typical home is supplied with a three-wire drop (although the trend is not
to drop, but to bury the feeders) that consists of two hot wires and a
return. The return line is grounded. The voltage from hot to hot is 240
Vrms, and is a single phase. The transformer that supplies the several homes
on the last power branch has a center-tapped secondary, so the voltage from
either hot to the center-tap is 120 Vrms.

I have heard the hot-to-center-tap voltage called 110 V, 115 V, 117 V and
120 V. That would mean the hot-to-hot voltage would be either 220 V, 230 V
234 V or 240 V. FWIW, the voltage at my home (between blackouts, I live in
Southern California) consistently runs about 119 Vrms.

High-power appliances (air conditioning, range, heating) are usually
designed to draw from the hot-to-hot 240 Vrms (this minimizes losses).
Lesser loads are connected from one hot to the neutral, hopefully with some
thought toward balancing the total load.

Light industrial users are often fed by a five-wire three-phase wye system
(three phases, neutral and safety ground). The nominal 208 Vrms value exists
from any phase-to-phase pair. The voltage from any phase to neutral is 115
Vrms. Heavy loads (large motors) are usually 3-phase models, and other heavy
loads (like industrial ovens) also draw phase-to-phase power. The
phase-to-neutral voltage is close enough to residential values that ordinary
lights, appliances and computers can be fed from this circuit. Again, you
should try to balance the phase-to-neutral loads. 

Regards,

Ed



Ed Price
ed.pr...@cubic.com
Electromagnetic Compatibility Lab
Cubic Defense Systems
San Diego, CA  USA
858-505-2780  (Voice)
858-505-1583  (Fax)
Military & Avionics EMC Services Is Our Specialty
Shake-Bake-Shock - Metrology - Reliability Analysis

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