Jim Mora wrote:
I don't know what total capacitance this puts across your transformer [assume it was loaded only with the filter] but I gather you are increasing the voltage from zero with a variac. I observed something similar with a 16 kV, 60 ma transformer loaded with an 0.006 ufd mica transmitting capacitor. Had my Simpson VM connected across the secondary and started to raise the voltage from zero. The secondary voltage increased as expected until the primary voltage reached about 30 volts at which time the voltage jumped high enough to blow out the HV multiplier in the meter. On closer investigation I found that there was a nonlinear ferromagnetic effect. Apparently the leakage inductance changed [probably increased] as the voltage increased until it went into series resonance with the capacitor. Easy enough effect to duplicate. I wonder if you experienced a similar phenomenon?Hello, I was adjusting safety gap for my used Terry filter. This will be for 4" demo coil which has a block diagram what stuff is and the wire path. Independent of that, I was setting my safety gaps to fire at 140v (measured) in, on the bench. Wow, just before the safeties fire, I get a 2" hot snap accross the filter input. It is a very dry out and that stress has to be seen across the outputs of my 12KV, 30+ma repotted neon. They safties start firing immediately afterwards. I closed them a bit, about right, and it still happens unless I ramp the voltage up very slowly. Is this a reverse resonance rise and a discharge of the filter caps? I should mention that I need to shunt some transorbs as they are set up for a 15KV PSU. I'm Glad the tranny is still working! Has anyone else ever seen this happen with the classic filter? Thanks, Jim Mora
As far as I'm concerned anyone running a capacitor-loaded NST without a suitably adjusted safety gap is just waiting for disaster and it will certainly strike some time. Terry's "filter" is perfectly safe but I've never figured out whether it is really necessary. Only reason I can see would be because a transformer can sometimes fail even with a properly adjusted gap.
Ed _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla