Technique of increasing the power factor of a power supply. Switching power supplies without power factor correction draw current in short, high-magnitude pulses. These pulses can be smoothed out by using active or passive techniques. This reduces the input rms current and apparent input power, thereby increasing the power factor.
Electricity supply require that the companies require that the power factor at which the supply is used shall be maintained at not less than 0.9 lagging, on average between one meter reading and the next. For any given wave shape, the power factor is defined as the ratio of Watts/(volts rms x ampsrms) Low power factors increase the KVa demand from the supply, reduces the useful load that can be safely handled by the cables and distribution equipment, and in some cases can attract additional tariff penalties. Lamp circuits which incorporate a choke, leakage reactance transformer, or an electronic ballast can have low power factors, often between 0.3 and 0.6. Low power factor from these circuits can be corrected by the addition of a compensation capacitor. These can be placed at the central point of the supply, locally for each group of luminaries , or integral within each luminaire.