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RE: NST phasing questions

Original poster: "Loudner, Godfrey by way of Terry Fritz <twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>

Hi Ed

The coiler with the 15KV/60MA and the 12KV/120MA wanted to connect the 120V
primaries in series for 240V operation. Then he wanted to connect the
secondaries in parallel. I think that his intention was to reduce current
draw from the service mains, and to get more current for a tesla coil. If
the primary impedances are different, then the 240V will not be shared
evenly by the primaries connected in series. This in turn will cause
voltages different from the ratings to appear at the secondaries. There are
potential problems with phasing together transformers which are not
identical. I was attempting a partial matching of the two NSTs on the
secondary sides. My previous calculation did not take into account the
secondary impedance of the 15KV/60MA. The new calculation gives a 62,500 ohm
resistor to produce a phased combination of 12KV/168MA. This calculation
assumes that the primary impedances are equal, and therefore is simply an
educated quess. 

Godfrey Loudner

> -----Original Message-----
> From:	Tesla list [SMTP:tesla-at-pupman-dot-com]
> Sent:	Sunday, May 27, 2001 1:53 PM
> To:	tesla-at-pupman-dot-com
> Subject:	Re: NST phasing questions
> Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <evp-at-pacbell-dot-net>
> Tesla list wrote:
> > 
> > Original poster: "Loudner, Godfrey by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>
> > 
> > Hi All
> > 
> > You have a 15KV/60MA and 12KV/120MA . Why not place a 50,000 ohms
> resistor
> > in series with the HV leads from the 15KV/60MA to reduce the output to
> > 12KV/60MA. Then you can parallel the two NST for a 12KV/180MA supply.
> Make
> > the resistor rated much above 720 watts to reduce losses from heating
> the
> > resistor. As to where to get such a HV resistor, I don't know.
> > 
> > Godfrey Loudner
> 	You can connect them in parallel without ANY resistor!
> Ed