130kW Coil Update
From: Greg Leyh[SMTP:lod-at-pacbell-dot-net]
Sent: Monday, January 19, 1998 2:49 PM
To: Tesla List
Subject: 130kW Coil Update
We did some hi-pot testing of the primary ckt, and found
a few corona trouble spots, and a couple of flashover spots
(including the safety relay!) These have been dealt with
for the most part, except for the pri-sec insulating sleeve,
whose altitude needs to be adjusted. After hipotting to
45kV we did some single-shot tuning of the coil set using
a static gap, starting at 5kV and increasing in 5kV steps.
No excessive induced voltages (<30Vpk) were found on the
LV AC equipment, except on the busbars of the SCR bank.
Here we saw about 130Vpk of voltage coupled by the electric
field. Two caps to pwr gnd fixed that.
In the sgl-shot mode at 40kV primary firing voltage, the
peak current at the base of the sec coil is about 51 Amps,
and the beat period is about 125-140 usec. When standing
outside on a plastic crate, P. Butterfield was measured to
be at about 400VAC RF above gnd, due to the electric field.
A gnd wire to Paul's arm confirmed the presence of voltage.
Single-shot streamers of about 6ft in length were observed
launching from the sphere at Vpri = 40kV.
Given that the primary energy is 216J and the rep rate is
about 0.75Hz, then the figure of merit of ArcLength/InputPower
for this coil is 288W per 6ft, or 48W/ft in the tuning mode!!!
Yet another example of why this is a silly Figure of Merit.
The next couple of days will involve work on the insulating
sleeve and on the rotary gap, with perhaps some low power
delta-mode tests in the < 50kW range.