Causes of Low Power Factor

Causes of Low Power Factor

Low power factor is undesirable from economic point of view. Normally, power factor of the whole load on the supply system in lower than 0·8. The following are the causes of low power factor:

1. Most of the a.c. motors are of induction type (1φ and 3φ induction motors) which have low lagging power factor. These motors work at a power factor which is extremely small onlight load (0·2 to 0·3) and rises to 0·8 or 0·9 at full load.
2. Arc lamps, electric discharge lamps and industrial heating furnaces operate at low lagging power factor.
3. The load on the power system is varying ; being high during morning and evening and low at other times. During low load period, supply voltage is increased which increases the magnetization current. This results in the decreased power factor.