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Re: New NST-sync tests, (Resonant charging effects)
In a message dated 99-06-24 05:07:35 EDT, you write:
<< > .. a little later, the voltage rise is less. I did not expect this
> > 135 degree ASVP phasing requirement.
>
> This makes sense, because your cap size is now larger than that required
> for resonance at 60Hz. As a result the phase is radically different. The
> cap size was much less than resonant size with your ballasted PT. As
> Malcolm pointed out the optimum phase can be calculated knowing the
> resonant charging frequency. It is however easier to reference the firing
> angle to the supply voltage zero crossing, so I will use ZC (zero
> crossing.)
> If Tank cap < Resonant size then best firing is just before supply ZC.
> If Tank cap = Resonant size then best firing is at or near supply ZC.
> If Tank cap > Resonant size then best firing is just after supply ZC.
> If Tank cap < Resonant size then little resonant voltage rise but big IK.
> If Tank cap = Resonant size then big resonant voltage rise and moderate IK
> If Tank cap > Resonant size then little resonant voltage rise & little IK
Richie,
Yes, this does make it clear to me now. I hadn't really thought it
through enough. But now i can't understand Terry's results with the
75 degree after-supply-peak-firing since he's using a LTR cap too of
the same basic size ratio as mine.
Thanks a bunch,
John Freau
> The further your cap value is from resonant size, the further the optimum
> firing angle moves from the supply voltage zero crossing. The graph of
> optimum firing angle against cap size is actually an inverse tangent !
> You can easily tell if a given ballast and capacitor is resonating above
> or below 60Hz by looking at the firing angle.
> I hope this makes the whole resonant charging thing a bit clearer.
>
- Richie,