Re: Series-ing Potential Transformers

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

Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 


No, this won't work.  In a NST one winding is wound in a different direction
than the first winding.  This means that the outer end of one winding hits a
60 Hz positive peak as the winding wound in the opposite direction is
hitting the 60 Hz negative peak.  The peak to peak voltage is twice what a
single winding would be.

In the case of 2 PTs hooked with a common center ground and each PT has the
same winding direction, each PT would hit a postive peak and negative peak
at the same time so the output would not be twice what the single xmfr would
give.  Each PT would hit 14.4 kV and then back to 0 kV as their phased
outputs would be exactly matched.

You can try it, but unless you have a very strange PT this won't work.

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913

 > >
 > >Bert is correct. I have (2) butyl rubber 7200 volt PTs.
 > >One of them only has one HV bushing terminal while the
 > >other has two. As I mentioned in an earlier post re-
 > >garding this issue, I series the two together for 14.4
 > >kVAC out to my HV rectifier for up to 20 kVDC to charge
 > >my 10 kJ can crusher/quarter shrinker capacitors w/in
 > >20 seconds. I run the single bushing one from ground and
 > >take the "floating" 7200 volts off of the single bushing
 > >of it and run it "piggie-back" to one side of the double
 > >bushing one, making sure it's properly phased and get 14,400
 > >volts out of the second PT's second bushing. I have had
 > >no problems with this setup as I know the BIL rating of
 > >both of the HV terminals of the second PT should easily
 > >hold off up to 14,400 volts.
 > >
 > >David Rieben