Electrical Systems: Power Factor Correction (2)

Power Factor Charges
Many utilities charge for low power. To measure power factor, the most common type of utility meter measures the total kVAr-hours and kVA-hours over the billing period and calculates the average power factor as:

PF = Cos [ ArcSin (kVArh / kVAh) ]

The most common methods of charging for low power factor are:

1. Adding a demand penalty when the power factor dips below a set amount (usually 90%)

2. Basing the demand charge on the supplied power Ps (kVA), rather than the actual power used Pa (kW).

3. Basing part of the overall charge on the reactive power kVAr, which increases as power factor decreases.