Power Factor Improvement

Power Factor Improvement

(i) Causes of low power factor

(1) Induction motor is the most commonly used AC motor. At full load 3 phase induction motor operates at PF (0.8) Lagging, while the PF of single phase motor of (0.6) lagging.

(2) The transformer draws a magnetizing current from the system, this current is about (0) lagging, other equipment like arc lamps, welding contribute to low PF in the system.

(ii) Effects of low power factor

(1) To meet the load requirement at low PF, the capacity of power plant, transmission &distribution equipment, has to be more than that which be necessary if the load where demanded at unity PF.

(2) For same active power, operation on existing power system at a low PF means over leading the equipment at times of full load.

(3) For the same active power, a low PF means greater current & higher energy losses & lower efficiency.

(4) Low PF causes the voltage regulation to be poor.

(iii) Advantage of power factor improvement

In installation of PF improvement device to rise PF results in the following effects& advantages:

(1) Reduction in circuit current







(2)Increase voltage level at load.

(3) Reduction of copper losses due to reduction of current.

(4)Reduction of investment of system facilities per KW in load supplied.

(5) Improvement in PF of generator.
(6) Reduction of kVA loading of generators & circuitsthis reduction of kVA may get rid of over loaded condition or release capacity for addition growth load.

(7) Reduction of kVA demand charge consumers.

(iv )How to improve power factor?

(1) Using static capacitors bank.

(2) Using synchronous condenser.

(3) Using static VAR compensator.