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power supply electronics query

C

clay

Jan 1, 1970
0
Need some help identifying several power supply capacitors that are
blown, inside a 200V DC power supply. The caps are axial (Poly film?)
and are labeled 103KV 630.

What are these? They are mounted across what appears to be a darlington
power transistor.

ca
 
C

caveat

Jan 1, 1970
0
clay said:
Need some help identifying several power supply capacitors that are blown,
inside a 200V DC power supply. The caps are axial (Poly film?) and are
labeled 103KV 630.

What are these? They are mounted across what appears to be a darlington
power transistor.

ca

You could try . . .

www.crosscomponents.com

I don't know that specific part number but they might be able to help you
with that.
 
V

Verizon News Group Server

Jan 1, 1970
0
These Are 10000PF Capacatiors (103) used as snubbers and depending on what
is connected to the Darlington configuration they may be film but my guess
would be paper to prevent power up surges that would POP the Collector
Emitter junctions since they are rated for 630 Volts in 200 VDC supply.
Paper caps would be hard to find these days but you can use a Mylar film
type to replace them. If they went more than likely your Darlingtons were
cooked. Check the surrounding circuitry there was a reason they cooked. Good
Luck.

Cliffybaby
 
C

clay

Jan 1, 1970
0
Cliffy,

A few more details. I don't think they are Darlingtons. According to a
service tech, they are 3 phase bridge rectifiers instead. There is
continuity (.4V drop) BOTH directions, tested in-circuit. So that is
probably bad news.

The Line voltage measures 250V, the wild leg on the rotary phase
converter measures 260V. The machines are rated for 208V, so that is bad
too. (working to resolve that) The paper/film caps are rated 630V DC,
250V AC, so that answers one of the failure questions. t
The have been running at 250V-260V for five years.

How do you size buck-boost transformers? Load KVA x Voltage drop% =
transformer KVA?

http://www.elliottelectric.com/References/buck_boost_transformers.aspx
 
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