I read in !emc-pstc that Rich Nute wrote (in
<200307011612.jaa01...@epgc264.sdd.hp.com>) about 'The transformer
screen/shield conundrum' on Tue, 1 Jul 2003:
>So, you can't really consider North American 240 V
>mains circuits in this discussion. We don't.
>
&g
Hi John:
> >If the breakers are 230 V/16 A and 120 V/15 A, then
> >the power distributed at 230 V is roughly twice that
> >at 120 V.
>
> But your '120 V' is also '240 V' for some equipment. Besides, I think I
> was being 'generous'; electrical energy consumption per head in USA i
I read in !emc-pstc that Rich Nute wrote (in
<200306302129.oaa24...@epgc264.sdd.hp.com>) about 'The transformer
screen/shield conundrum' on Mon, 30 Jun 2003:
>I disagree that the same power is distributed at
>230 V and 120 V.
We have a certain amount of misunderstandi
Hi John:
> >For 3% voltage drop at maximum rated load, the
> >source resistance is about 0.2 ohm. So the
> >maximum rms current would be system nominal
> >voltage divided by 0.2 ohm, or 600 amps for 120
> >V and 1150 amps for 230 V.
>
> For 230V, there are two modificatio
I read in !emc-pstc that Rich Nute wrote (in
<200306301811.laa23...@epgc264.sdd.hp.com>) about 'The transformer
screen/shield conundrum' on Mon, 30 Jun 2003:
>For 3% voltage drop at maximum rated load, the
>source resistance is about 0.2 ohm. So the
>maximum rm
Hi Richard and John:
> >[R_Hughes >] I know it as prospective short-circuit current, but maybe I
go
> >boldly whereas you boldly go?
>
> Do we know what the current values are in various countries, for
> equipment connected to wall-sockets? Assuming that the mains lead has
> the r
I read in !emc-pstc that richhug...@aol.com wrote (in <6C87B93E.0C9D7087
.0ba45...@aol.com>) about 'The transformer screen/shield conundrum' on
Sat, 28 Jun 2003:
>[R_Hughes >] I know it as prospective short-circuit current, but maybe I go
>boldly whereas you boldly
Rich,
RN> I'm surprised that, today, a SMPS would used screen/
shield construction.
[R_Hughes >] Not all power supplies are switch mode, even today. I bet that
the HiFi addicts who say that they can hear the difference between a valve
amp and a transistor amp would absolutely hate the idea o
I read in !emc-pstc that Rich Nute wrote (in
<200306271743.kaa29...@epgc264.sdd.hp.com>) about 'The transformer
screen/shield conundrum' on Fri, 27 Jun 2003:
>The screen/shield must be capable of carrying
>the full fault current and is often tested
>using the 25-amp t
I read in !emc-pstc that Rich Nute wrote (in
<200306271956.maa00...@epgc264.sdd.hp.com>) about 'The transformer
screen/shield conundrum' on Fri, 27 Jun 2003:
>I would agree that this current, at a very small
>contact area, is the driver for the hole in the
>screen
Hi Richard:
> You mention a few times the 25 Amp test. The designs I have seen that try
> and use this approach (and I don't ever recall seeing a design I was happy
> with) were all switch mode power supplies where there was an input fuse of
> about 2A, meaning that the test would be
bject: The transformer screen/shield conundrum
Hi John and Richard:
The transformer screen/shield between primary
and secondary windings is intended to carry
the fault current in the event of a failure
of basic insulation between the primary and
the screen/shield.
The screen/shield must be
Hi John and Richard:
The transformer screen/shield between primary
and secondary windings is intended to carry
the fault current in the event of a failure
of basic insulation between the primary and
the screen/shield.
The screen/shield must be capable of carrying
the full fault current and
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