Re: Inductive Kick Effects

Hi John, Terry, Malcolm, Reinhard, all,

>From what I remember the biggest inductive voltage kick occurs if a 100BPS
rotary is set to fire near the peak of the SUPPLY voltage waveform.  This
is in contrast with the usual setting near the zero crossing with a
matched resonant capacitor.  Maybe that is why it has only just become
noticed now !

As the firing approaches the peak of the supply voltage,  more voltage is
slammed across the ballast when the gap closes.  This gives the greatest
voltage flyback on the charging cycle that follows.  However firing near
the peak in the supply voltage gives poor results because although the
capacitor voltage rings up to a high voltage it then falls to a lower
voltage before the bang,  resulting in poor power throughput,  and lousy
power factor.

BTW John,

My simulation showed about 13% voltage in the opposite direction before
the next firing,  and the power factor was pretty good at about 0.86.  I
also noticed that the bang ocurred slightly after the maximum voltage
point ?

PS. Thanks for reporting this phenomena with all the measurements.  It
makes it easier to guess what is going on.


						- Richie,

						- In sunny Newcastle.