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Series Caps, a cuationary note
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To: mail11:;-at-cimcad.enet.dec-dot-com (-at-teslatech)
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Subject: Series Caps, a cuationary note
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From: I am the NRA <pierson-at-cimcad.enet.dec-dot-com>
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Date: Mon, 14 Nov 94 12:49:09 EST
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Cc: pierson-at-cimcad.enet.dec-dot-com
When pros use series caps (or series anythings... 8)>>) for HV work, they
take one precation i did not see mentioned:
Pu a HIGH VALUE resistor in parallel with each element of the stack, that is
with each cap. This forces the voltage to divide equally across them which
may not otherwise happen. As a side effect, it will drain down the caps after
use. It adds a samll loss, but if it saves the bank (or the operator...)....
Thus:
V
|
+-+
| |
C R
| |
+-+
| |
C R
| |
+-+
| |
C R
| |
+-+
|
V
The exact value of the R is not critical, tho it should be high to avoid
losses (and avvoid expensive resistors. Depending on teh voltage on the caps,
a spark gap, set a smidge above the normal operating votlage (and below the
failure voltage...) of the cap(s) is also easy to do and may save the bank...
Individual gaps can be made of wire, and, if a series bank is employed one can
be placed across each element...
regards
dwp