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Re: HV Xfmr Protection networks
From: Mark S Graalman[SMTP:wb8jkr-at-juno-dot-com]
Sent: Thursday, June 26, 1997 4:19 AM
To: tesla-at-pupman-dot-com
Subject: Re: HV Xfmr Protection networks
Gary,
Actually the old recommendations of having "lossy" caps as bypasses are
false, the choke system is what should be "lossy" not the bypass. The
idea
you suggest will work just fine provided the circuit board material will
withstand
the voltages. Safety gaps need not be critical in construction, but I
would
recommend using rounded electrodes rather than pieces of wire or a
pointed
shape. I usually set the safety gap just a bit wider than the transformer
is
capable of firing.
Mark Graalman
Toledo, Ohio
Callsign: WB8JKR
Member: Society of Telecomunications Engineers
TCBA member # 1399
On Wed, 25 Jun 1997 23:42:59 -0500 Tesla List <tesla-at-pupman-dot-com> writes:
>
>From: gary Lau[SMTP:lau-at-hdecad.ENET.dec-dot-com]
>Sent: Wednesday, June 25, 1997 10:51 AM
>To: tesla-at-pupman-dot-com
>Cc: lau-at-hdecad.ENET.dec-dot-com
>Subject: HV Xfmr Protection networks
>
>All of the archived materials I've seen on this subject
>recommends using 3-4 barium titanate doorknob caps in series
>for the bypass caps. I understand that these are considered
>"lossy" at high frequencies, desirable in this application.
>
>But is this necessary? I was planning on making caps from
>.09" thick fiberglass circuit board stock, easy to work with and
>easy to get any reasonable value. With a dielectric rating of
>11.8 pf/sq inch (measured) and 700V/mil (from MATH.TXT), this
>should be good to 63KV DC, maybe 30KV AC? As I'm using OBIT's
>which have a center ground, I'd use a pair of these caps,
>shooting for ~700 pf each to RF ground.
>
>For the safety Gaps, do these need to be anything more robust or
>complex than a short piece of heavy copper wire at the proper (?)
>spacing across each bypass cap?
>
>Gary Lau
>Waltham, MA
>
>
>
>