Re: PFC Question

• To: tesla@xxxxxxxxxx
• Subject: Re: PFC Question
• From: "Tesla list" <tesla@xxxxxxxxxx>
• Date: Thu, 03 Nov 2005 21:09:01 -0700
• Delivered-to: chip@pupman.com
• Delivered-to: tesla@pupman.com
• Old-return-path: <vardin@twfpowerelectronics.com>
• Resent-date: Thu, 3 Nov 2005 21:09:43 -0700 (MST)
• Resent-from: tesla@xxxxxxxxxx
• Resent-sender: tesla-request@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