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Spark Over Voltage
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To: mail11:;-at-cimcad.enet.dec-dot-com (-at-teslatech)
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Subject: Spark Over Voltage
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From: I am the NRA <pierson-at-cimcad.enet.dec-dot-com>
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Date: Wed, 22 Feb 95 18:19:40 EST
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Cc: pierson-at-cimcad.enet.dec-dot-com
Short version:
Sparkover voltage is affected by a LOT of things: electrode shape, spacing,
air temperature, humidity, illumination (yes...). Its not linear with gap
length. It falls as air pressure falls, then rises as a hard vacuum is reached.
It ALSO rises as air pressure is inreased. When gaps are used for measurements
they are carefully calibrated. HF/RF will jump larger gaps than the same DC of
60 Hz.
Details/refs:
Dielectric Phenomena in High Voltage Engineneering
F W Peek
1915
(STILL cited as a source.)
5 cm (?) spheres. Spheres, anyway.
Spacing
0.1cm/0.0395" 1.0cm/0.395"
60 Hz 4.95KV 31.8KV
40KHz 3.65KV 28. KV
voltages are peak.
AC from a HF alternator.
Electrical Engineer's Handbook, Fink & Beatty
1 cm, 31.4KV, peak
(which is close to Peek, above...)
(I remembered it as more like 25KVAC/Inch. Live & learn...)
=====================================
My impression is that natural lighting does not follow a mumble v/cm type
relation, but proceeds in rapid steps, a few 10s of meters per step, with the
hot channel statign ionized & low drop behind the leading point...
regards
dwp