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NST Max Ratings and Mains Resonance (fwd)
---------- Forwarded message ----------
Date: Thu, 12 Feb 1998 15:54:09 -0500
From: Thomas McGahee <tom_mcgahee-at-sigmais-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Cc: MALCOLM-at-directorate.wnp.ac.nz, Wysock-at-courier8.aero-dot-org
Subject: NST Max Ratings and Mains Resonance
Bill, Malcolm, and other interested coilers,
Besides the resonant rise that Malcolm mentions, there is also
the fact that when the main cap and the transformer are set to
resonate at the mains frequency, the transformer is capable
of providing current levels that are several times the usual
'current-limited' value. If the wire in the secondary is too
thin, then you can actually burn out the secondary winding
under these mains-resonant conditions.
Thus, with the proper resonant conditions a 15KV 60 MA
NST can charge the mains cap up to voltages in excess of
40KV, and at a rate that is much greater than the 60 MA
rating would suggest. Note that both the extra voltage and
extra current can contribute to the NST failing prematurely.
Hope this helps.
Fr. Tom McGahee
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: capacitor energy vs pwr factor
> Date: Thursday, February 12, 1998 12:55 AM
>
>
> ----------
> From: Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> Sent: Wednesday, February 11, 1998 5:10 PM
> To: Tesla List
> Subject: Re: capacitor energy vs pwr factor
>
> Hi Bill,
>
> > From: Wysock, William C. [SMTP:Wysock-at-courier8.aero-dot-org]
> > Sent: Tuesday, February 10, 1998 12:57 PM
> > To: Tesla List
> > Cc: ttr
> > Subject: RE: capacitor energy vs pwr factor
> >
> >
> > To all working with NST's as a power source.
> >
> > With any NST (containing a magnetic leakage shunt in its core;
> > whether it be "stock" or "modified" for higher current) and
> > irrespective of using external a.c. electrolytic power factor
> > correction capacitors, there seems to be something
> > fundamental missing in everyone's calculations. Remember,
> > you can hard-wire short the secondary terminals on an NST
> > without burning the thing up. If your NST was rated for example,
> > at 60 ma., you will have 60 ma. flowing in the short circuit. BUT,
> > you will have "0" volts. The voltage output of an NST is
> > inversely proportional to the amount of current being drawn.
> > The only time you have say, 15 KV rms at the output terminals
> > is when NO current is being drawn. The bottom line is that
> > at no point do you have 15 KV *and* 60 ma., at the same time.
>
> I think that only applies to a resistive load. I've seen a
> transformer ringing up with a capacitive load. I've seen Q's in the
> vicinity of 6 at mains frequency with one combination I checked.
>
> ?
> Malcolm
>
> > The load voltage and current will be less (for the point where
> > the current sine wave phase angle crosses the voltage sine
> > wave phase angle,) to yield maximum usable power.
> >
> > Bill Wysock
> > -------------------------------------------
> > Tesla Technology Research
> <snip>
>