Re: Capacitor Help

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Ed Phillips <evp@xxxxxxxxxxx>


Hi Malcolm,

YES, however, the steady state response from spice using LTR of 
1.6*Cres is close to that of an unloaded NST (I just cant remember 
whether higher or lower).  It takes either a transient or 
feroresonance (as Ed mentioned) to get the voltage higher.  Now that 
I'm thinking about the subject, it seems if ferroresonance occurs at 
2.6*Cres, it will occur more at 1.6*Cres cause more of the inductive 
reactance of the transformer is cancelled by the capacitive reactance 
of the load (results in higher current limits) and the transformer 
inductance doesnt need to be reduced as much due to saturation. I 
just may experiment with this next summer to see where ferroresonance 
occurs with respect to Cp values.

Gerry R."

   It is easy to get ferroresonance even if the capacitance is less 
than  "Cres" based on leakage reactance calculated from ratio of 
rated terminal voltage to rated short-circuit current.  The 
permeability is higher at low voltages than at operating voltage, or 
at least it was in my case.  The particular experiment involved a 15 
kV, 60 ma transformer with a 0.006ufd 30 kV mica transmitting 
capacitor across it.  That's a lot less than "official" Cres.  In 
thinking back I believe the critical primary voltage was less than 
30.  Anyhow, the high-voltage range on that poor VOM is still shot!

Ed