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Constant Voltage Transformer Question

D

David Lesher

Jan 1, 1970
0
At work I've found this happens with three phase, and I've seen the
neutral wire carrying substantial current, especially when I measure the
current near areas where there is one or more copiers. They seem to
have a very high current draw at times, when the fuser comes on.

When HP-35's and such were first appearing; I read a story about a
building where HVAC motors, fluorescent lamps, elevators, and you
name it all failed regularly. Only clue was TI calculators would
regularly crash if plugged in.

After a large effort; turns out the Mini-sized (as in British car)
copier machine was putting nasty spikes on the line/neutral, nasty
enough to degrade motor insulation and other windings. They fitted
it with (!) lightning protection (Poly-phaser or such) and that
solved the issue. One wonders how ?Xerox? got UL approval....
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that David Lesher <[email protected]>
After a large effort; turns out the Mini-sized (as in British car)
copier machine was putting nasty spikes on the line/neutral, nasty
enough to degrade motor insulation and other windings. They fitted it
with (!) lightning protection (Poly-phaser or such) and that solved the
issue. One wonders how ?Xerox? got UL approval....

UL approval for what? There is no product safety issue. There IS an EMC
issue, but the US has not adopted IEC/EN 61000-3-3, which would probably
have caught the problem.
 
R

Rich Grise

Jan 1, 1970
0
And inside the microwave is a ferroresonant xfmr.....

It turns out, at least in the last one I took apart, it _looks_ like a
ferro, but that oil-filled cap is merely the filter cap in a half-wave
doubler. The tranny looks like a ferro, because the primary and secondary
are separate windings, with a space between them. But there are no shunts,
and no resonant winding. )-;

It's a linear transformer, and the cap is only a HV oil-filled cap.

How mundane. ;-)

The maggie _is_, however, the other diode in the half-wave doubler. ;-)

Cheers!
Rich
 
M

Mark Zenier

Jan 1, 1970
0
It turns out, at least in the last one I took apart, it _looks_ like a
ferro, but that oil-filled cap is merely the filter cap in a half-wave
doubler. The tranny looks like a ferro, because the primary and secondary
are separate windings, with a space between them. But there are no shunts,
and no resonant winding. )-;

It's a linear transformer, and the cap is only a HV oil-filled cap.
The maggie _is_, however, the other diode in the half-wave doubler. ;-)

There are shunts (or some sort of welding trick), so that the transformer
current limits. It's like a Neon sign transformer.

Mark Zenier [email protected] Washington State resident
 
R

Rich Grise

Jan 1, 1970
0
Mark said:
There are shunts (or some sort of welding trick), so that the transformer
current limits. It's like a Neon sign transformer.

Mark Zenier [email protected] Washington State resident

I tried to post this as an attachment, but my post seems to have gone
to the bit bucket. As I said in the other post, I stand corrected.
Thank you. I realized I have a uWT right here, so "I'll take a picture
to prove my point," I sez to meself.

Imagine my surprise! :)
http://www.neodruid.com/images/dscf0145.jpg

Cheers!
Rich
 

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