RE: RSG and NST's

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <gary.lau@xxxxxx>

Hi David:

I'm sure you know better, but I still have to ask this to cover all
bases.  Can you say with certainty that prior to the NST failures, that
you were careful to ensure that the RSG was spinning at 120BPS or
greater before energizing the NST's?  Was there a reasonably set safety
gap in parallel with the RSG?  And any possibility that the RSG gap
clearance was excessively wide?

I would agree with you on the cap feeling the stress more-so than the
transformer at higher BPS, due to the higher Irms.  But I also think
that this would be a greater problem in pig-powered systems.  With NST's
or other lower powered sources, the bang voltage will diminish with
higher BPS's.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Saturday, November 27, 2004 2:18 PM
> To: tesla@xxxxxxxxxx
> Subject: Re: RSG and NST's
>
> Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
>
> Hi Gary, Dr,
>
> I'm not too sure which one of you are "right" on this ;^) I have
> experienced near cascading failure of an NST farm when try-
> ing to run an asynch rotary gap with them! I'm not too sure
> what the BPS rate was but I think it was in the 300 to 350
> range - 6 rotary electrodes on a 3450 rpm motor. Anyway,
> I had (6) 15/30 NSTs in parallel and almost as soon as I
> fired it off, the output quickly went down to almost zero. In-
> spection revealed that one of the transformers had failed.
> Once this transformer was removed and I was operating
> on 5, the same thing happened again almost immediately
> after power up. So now I had 4. Didn't take long to figure
> out that this was NOT going to work :^O I don't think 300
> or so bps would be considered LOW bps. One thing that
> I am pretty sure of is that whether or not high bps is more
> stressful on the transformer from resonant rise or whatever,
> it is more stressful on the primary capacitor due to higher
> RMS currents. This particular .083 uFd, 84 kV cap was
> quite robust though and never even "hiccupped" then or
> for the next several years after that after I had finally upgraded
> the transformer(s) to a single 10 kVA, 14,400 volt pole
> pig and got bright, thick 8 to 10 ft. sparks for runs of se-
> veral minutes of non-stop operation at a time. So for me,
> NSTs are just too fragile for serious coiling and since
> using pole pigs, transformer failures have ceased , with or
> without any type of protection/filter circuitry ;^)
>
> David Rieben

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