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Re: 2 questions on resonance
In a message dated 99-04-08 05:33:22 EDT, you write:
<<
> Malcolm and all,
> One can! Probably the best analysis of this was done by Glasoe in "Pulse
> Generators", section 9.5 (AC Resonant Charging). Although the math is
fairly tedious, the result is that the capacitor voltage can reach Pi/2
> or 1.57 times the peak of the applied sinusoidal voltage for the
> lossless case. This means the output can reach up to 2.22 times the RMS
> faceplate voltage (or 33 kV) for the lossless case. While Ohmic losses
> will reduce this a bit, this implies that a 15 kV transformer might
> stress the tank cap to over 30 kV. Upon oscillatory discharge, the
> dielectric will be stresses to 2X this value, or about 60 kV. This is
> another way of looking at why the tank cap's DC rating should be at
> least 3-4X the expected applied RMS voltage. And it can get worse... if
> the gap missfires and we catch the NEXT peak, the voltage could be Pi
> times the peak of the input sinusoidal voltage (approaching 66 kV!).
> Practically speaking, I believe this voltage multiplication effect
> occurs in my resonant charging system, since I'm running with 18 gaps
> (0.54") off a pair of 15-60's, and at full power the system is actually
> firing at between 3-4X per half cycle (albeit somewhat chaotically).
> -- Bert --
>>
Bert, Malcolm, all,
The Glasoe reference is the one I used also. I have measured a
substantial resonant rise in my TC system with the sync gap. I do find
that usually a cap that is somewhat larger than that predicted by the
resonance formula is better. Usually the resonant curve for the NST
is pretty broad. I'll try some more tests using different sized caps
and see what happens.
John Freau