Re: Low-voltage NST

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jason Petrou by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jasonp-at-btinternet-dot-com>

Antonio
There are a number of possibilities:

> I obtained recently a NST rated 5000 V x 30 mA. It has two high-voltage
> terminals with ceramic insulators, two input terminals for 115 V,
> and no ground connection at the case or anywhere.
It is posible that the centre tap on the secondary is going to the mains
earth - although i have never seen this before! Perhaps you could post the
make of the transformer up so that someone with a similar power supply could
have a look...

> I imagine that without a ground connection I can operate it with
> one of the output terminals grounded. Do someone have experience
> with similar NSTs?
It is possible to operate the NST with one of the terminals grounded, but
probably pointless. The main reason for a centre tap on NSTs is this...

Take a standard 12/60 transformer. The voltage difference at peak between
the two terminals (open circuit) is 12KV. If the transformer is centre
tapped to ground, this difference still occurs - but one terminal is +6KV
and one is -6KV. This pust much less strain on the windings of the NST. If
the transformer should be grounded but isnt, then you get +12KV at one
terminal, +6KV at the other, and a 0KV terminal. (this oscillates at line
frequency - 50/60Hz)

I would find out the make, and see if the case needs grounding. If it does
and yourre ruing it with no ground, then it could float at HV, then 'bad
stuff' starts to happen!!!

Regards,
Jason