Re: PFC Question

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Ed,

The pig is close to an ideal transformer and the impedance it 
presents at its input is a reflection of the load impedance it is 
driving (a short when the SG fires, a capacitance when the TC caps 
are charging).  If Cp is LTR, the impedance of the ballast will 
dominate and the impedance presented to the variac will look 
inductive.  This is why the PFC caps need to be in parallel with the 
combined load the ballast and pig presents.  The PFC caps only 
correct for inductive loads.  If you are running the pig with a STR 
Cp value, then  PFC caps wont work cause the load presented to the 
variac will be capacitive (maybe a PFC inductor will help here).  PFC 
caps can also be placed upstream of the variac as well to correct for 
the inductance added by the variac itself.  However, the variac 
inductance will be a function of the variac setting (zero inductance 
when variac_out = variac_in)

You can calculate the PF (without PFC) by taking the TC Cp and 
transforming it to the primary of the pig (multiply the Cp by N^2 to 
get lower capacitive reactance at the pig primary).  You can figure 
the resulting reactance from the combination of the ballast inductive 
reactance and the capacitive reactance at the pig input. Use this 
resulting reactance with an equivalant resistance in series with it 
where the resistance will model the real power draw (bps * bang energy).

Gerry R.


> Original poster: Esondrmn@xxxxxxx
> Does anyone know or venture to guess how far off the power factor is 
> on this kind of set up.  The transformer is primarily an inductive 
> load, but does some of that get canceled by