Re: Gap Dwell Times (formerly: Beating Solved)

To: tesla-at-pupman-dot-com
Subject: Re: Gap Dwell Times (formerly: Beating Solved)
From: Jim Fosse <jim.fosse-at-bdt-dot-com>
Date: Fri, 27 Sep 1996 07:21:00 GMT

>Date: Fri, 27 Sep 1996 08:13:59 +1200
>From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
>To: tesla-at-pupman-dot-com
>Subject: Re: Gap Dwell Times (formerly: Beating Solved)
>
[snip]
>I started from k approx dF/F, and ringup time = 1/2dF so you can see 
>how I derived that. The problem when cutting the gap off (if you 
>could) when Ip is maximum is that with k<1, most of the primary 
>energy is coupled to the primary. I tried doing exactly this with the 
>MOSFET gap and the spikes hit the roof. Virtually none of that energy 
>was coupled to the secondary. The spikes in a real gap would have re-
>ignited it anyway.
Malcolm,
	That artifact is called "leakage inductance" and it behaves
exactly like one had put an inductor in series with the transformer.
To make matters worse, it follows V= Ldi/dt, so the faster you quench
your gap, the higher V will be!

>I found the ideal dwell to be when the secondary was fully rung-up 
>and the primary had virtually nothing left. Even then, quenching at a 
>primary zero-crossing is a no-no because of spike generation. I sent
>some photos I took of this process to several people. 
>
Would anyone like these scanned and posted if acceptable to Malcolm?

	jim