From: "Barton B. Anderson"
Date: Fri, 17 May 2002 00:52:58 +0000
Subject: Re: [TSSP] Topload breakout potentials
Hi Paul, All, I performed an arc voltage test tonight to find the cap voltage. I used 2 brass spheres of 1.25" diameter. This is my safety gap and it was used as the sparkgap with little effort as it's across my rsg. I checked calibration of the Simpson panel meter against a calibrated Fluke. A very slight adjustment (not enough to count). It was on the money from 0 to 240Vac. I ran the SRSG as before at 180Vac input and increased ballast current. When the toroid broke out, I logged left the variac in position and dropped the voltage back to zero. For the arc gap, I used a dial caliper for accuracy of gap measurements. I also cleaned between electrodes with steel wool between tests (I blew out fibers after each cleaning). I started at 0.5" and turned the voltage up to 180Vac. At 0.35", the gap arced which should be near the SRSG voltage. With a sphere diameter of 1.25" spaced at 0.35", the arc voltage should be around 22.3kV using the equations from the North report (chapter 7 - HV Insulation). E*4*d/(d/R+1+sqrt((d/R+1)^2+8)) Where E is 3,000,000, d is total gap spacing in meters, and R is electrode radius in meters. So Paul, if North is correct, then cap voltage is 22.3kV (about 34% higher than the transformer voltage). I'm not sure why this is (suspect STR charging), but it definately broke out on the toroid at 0.35" with 180Vac input. Take care, Bart Paul wrote: > John, Bart, > > Thanks for the details on the primary winding, that's very helpful. > I'll work through those this evening. > > John wrote: > > I seem to see about 220kHz which doesn't seem correct. > > For the larger toroid, that sounds a bit high. I've had to > guess a few things...can you measure the secondary inductance? > > > you mention a base height of 20 something > > inches. What does this base height refer to? > > Height of the secondary base above the ground plane. In you case > it's hard to decide what to call the ground, so I'm happy to > tweak the base height, wall distances, etc in order to get a > match with measured resonances. > > Bart's secondary Fres was about 5% higher than predicted, which is > a big discrepancy. I had the walls at 60" and the roof at 120". > I took these away altogether and got > > Measured Modeled Error > ba0: 69.8 kHz 69.9 kHz +0.1% > > which is more like it. I guess that even though there is a wall > and a ceiling present, they are not terminating much of the E-field. > > Bart's coil present an even bigger mystery now, because as well as > the good match on the secondary we also have for the primary > > Measured Modeled Error > ba0: 61.3 kHz 61.5 kHz +0.3% > > so the -12% tuning is genuine and we ought to be getting less than > 17kV/cm on the toroid. > > Is there any possibility that some resonant effect in the charging > circuit is giving a larger than expected bang? Bart, can you confirm > the toroid dimensions 30"x9", sorry if I've asked before but so > much stuff crosses my desk at the moment I'm losing track! > -- > Paul Nicholson, > --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.