Hi DC,I'm not sure if the chokes helped or not, if it was the main gap setting, but 9 MOV's is about an 18000 volt "assumption of conduction". Terry designed the MOV's in the Terry Filter to be just below the NST's peak voltage. Not quite linear across the NST voltages, but still below it. I think 8 MOV's on a 12kV NST would be about max. On the 15kV, we could probably go as high as 10 as a max.
As we add more MOV's, it's similar to opening up a safety gap. There is a point where the safety gap is too wide and does no good, or where the MOV's are too many and also do no good. From a TCML overall recommendation, I would say keep the MOV quantity based on the rms allowable voltage (1000V) of the MOV (as per Gary's post) and based on the peak voltage of the NST to just be under it as a maximum for the number of MOV's. Here is my suggestion.
Vp/MOV allowable rms voltage/2 = Maximum MOV quantity.Vrms/MOV allowable rms voltage/2 = Minimum MOV quantity (we don't want MOV's firing too often).
Terry's filter is simple but also very well thought out. Not only does it have a sort of solid state safety gap, but it also incorporates a mechanical safety gap as a backup. And this is above and beyond the filtering portion. Kudo's to Terry!!!!
Take care, Bart DC Cox wrote:
I use 9 MOVs in each leg with 12/60s. No nst failures, but I also use air core chokes on the other end of the filter. Dr. Resonance On Fri, Jun 20, 2008 at 10:40 AM, b alex pettit jr <a_pettit_jr@xxxxxxxxx> wrote:On a related topic, How may MOVs are required for safe operation in the Terry Filter ? I have 8 per leg for the 12KV/60ma - just used the full set of MOVs provided in the kit, maybe too many ? Since they are rated at 1800v, 6000/1800 = 3.33 per side, but seems as if most use many more than that ... ?? Whats the consensus ? Thanks, Alex P _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
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