PFC Discharge Resistors Switching

Yeah, I think that second one.....

http://www.electronicproducts.com/Passive_Components/Resistors_and_Potentiometers/Cap-discharge_resistors_stabilize_PFC_operation.aspx

Ugh... Stepped PFC control. Cruizin' for a bruizin'.

If if they are called "Discharge" resistors, then that inherently means after the caps are switched out. Otherwise, they would be called "precharge" resistors used to soften the capacitor charging current inrush. Sometimes though, the design may use them for both functions.

Thanks gents for the clarification. your replies were helpful. Well last week i did some thermography for a sister plant and i found out that in some steps, all the 3 risitors for the 3 phases were approximately at the same temperaure about 178 degrees and in other steps i found one resistor or 2 are at room temperature. The majority have high temperatures which implies that that's their normal operating temperatures. I was suprised the PFC cubicles were lacking any means of cooling, like fans. They once had a fire at one PFC cubicle (the one with 1 or 2 resistors at room temperature) and their capacitors keep on bulging.