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Re: Dump the RSG
From: David Sharpe[SMTP:sccr4us-at-erols-dot-com]
Reply To: sccr4us-at-erols-dot-com
Sent: Saturday, November 08, 1997 2:08 PM
To: Chip Atkinson
Subject: Dump the RSG
Chip, All
About 3 or 4 years ago (Richard, correct me if my memory is wrong),
Richard built a small quench gap using one bottle of a 12kV GE vacuum
interrupter. The electrode assembly was forced open by a threaded rod
assembly to 1mm. Gap worked ok up to 1kVA input, but ran HOT :^C
As mentioned by Charles, mechanical inertia will probably limit you
to 100pps, more likely much less. Heating may be a big bugaboo,
unless oil immersed, or force air cooled. Too much heating will
probably break the vacuum seal, ruining the interrupter.
600A is continuous current rating, usually the interrupters are rated
by asymmetric interruption capacity (AIC) in kA. Obviously a one-time
event. Usually with medium voltage breakers, interruption capacity is
measured in MVA, with 200, 350, 400 being common in the industry.
My math is slow today (after vacation) but even if multiphase, single
phase, PF not withstanding, many kA can be successfully interrupted
usually in less than 1 cycle. This is why vacuum interruption
technology has become a very big business in power switchgear. Another
advantage is size, compare a 600A vacuum bottle 15kV class breaker
to an old GE AK series roll out 15kV mechanical air blast breaker.
In size, mechanical and electrical performance benchmarks, ongoing
maintenance costs, vacuum will win hands down. Even 600VAC units are
now available for high horsepower 480V,3ph motors (250 - 1000HP).
DAVE SHARPE, TCBOR