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Re: PFC & NST question

Hi Jan,

At 07:31 PM 02/11/2000 +0200, you wrote:
>Hi,
>
>if I connect a completely matching PFC capacitor to the primary side of my
>NST so I get resonance at line frequency, do I need current limiting for
>the NST? I have the impression the PFC cap will also match/null out the
>effect from the chokes?

No.  A PFC cap is place in parallel with a low impedance voltage source(the
AC line) and the NST primary.  The system cannot resonant up in that case
since the low impedance AC line will act as a giant loss.  Never put a PFC
cap in series with the NST.  That would be very "bad"!...

A PFC cap simply pulls current at a different time than the inductor of the
NST primary and keeps it in sync with the voltage.  The NST current is the
same as before but the AC equipment supplying the PFC and NST sees far less
current stress.

>
>Does resonant charging have the same effect as a PFC capacitor?

No.  The secondary case really is a series resonant circuit where the
voltages and currents can "ring up".  The placement of a PFC cap in the
circuit makes this impossible.  The difference really lies in the addition
of source and load resistances to our typically simple LC circuits.

Cheers,

	Terry 

>
>thanks,
>Jan
>
>
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