From: Paul
Date: Wed, 30 May 2001 18:37:01 +0100
Subject: Re: [TSSP] Secondary in motion
More movies. This time showing voltage *gradient*, both around 1.7 Mbyte, http://www.abelian.demon.co.uk/tssp/tfsm2-pdv-k=0.12.mpeg http://www.abelian.demon.co.uk/tssp/tfsm2-pdv-k=0.20.mpeg The vertical FSD for both movies is 0 to 425 V/turn for a primary bang voltage of 10kV. The gradient has been full-wave rectified, so its always +ve on the graph. I've left off all the trimmings they considerable increase the mpeg size. Trace duration, both movies, is 0 (bang) to 31uS. The corresponding static plots (with 100V firing voltage) are in http://www.abelian.demon.co.uk/tssp/tfsm2-p-k=0.12.gif http://www.abelian.demon.co.uk/tssp/tfsm2-p-k=0.20.gif and the secondary voltage movies, which you've already seen, are in http://www.abelian.demon.co.uk/tssp/tfsm2-p-k=0.12.mpeg http://www.abelian.demon.co.uk/tssp/tfsm2-p-k=0.20.mpeg The actual peak gradients are, k=0.12: max=400V/turn @ 24% height, 17.75uS, frame 59 k=0.20: max=410V/turn @ 90% height, 11.29uS, frame 37 Not a vast difference there in the peak turn/turn voltage. You have 17.72 turns/cm on this coil, so if you exceed 1.47kV/turn you will be exceeding 26kV/cm longitudinally. With some naive reasoning along these lines, you should be comfortably immune from turn/turn breakdown (insulation permitting?) up to a firing voltage of 10kV * 1470/410 ~= 36kV. Would be interesting to find someone who's having real trouble with racing arcs - a well tuned, bottom heavy coil that has an aggressive primary, and put their setup through the mill - see how that comes out. PS, by 'bottom heavy' I mean a coil that has a fair amount of its distributed capacitance near the bottom of the coil, resulting in a more rapid rise in voltage in that region, as illustrated by the exaggerated artifical example #5 in http://www.abelian.demon.co.uk/tssp/pn1710/ So far, to me, it doesn't look like k=0.2 is a problem for your coil Terry, I'll attempt to contrive a k=0.3 arrangement and run that one. Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.