What is Power Factor Correction?

Power Factor of an electrical installation is the ratio of the “real” power consumed and the “apparent” power supplied to the installation. Real power is expressed in kilowatts (kW) and apparent power expressed in kilo Volt Amps (KVA). A power factor of 0.8 means that an installation is using 80% of the power being supplied to it, so improving the power factor can have some good benefits.

Example

An electrical installation has a “real” (kW) demand for electrical energy of 500kW and a power factor of 0.8.  Power factor is expressed as kW/KVA, so the “apparent” power required to produce this “real” power would be

500/0.8 = 625KVA.  Improving the power factor will reduce this KVA and therefore reduce the supply transformer requirements or increase the available “real” power from the transformer.

The power factor can be improved by using “Power Factor Correction Equipment”, which contain capacitors and related protection and control equipment and are connected to the main switchboard. Following improvement of the power factor to, say, 0.99 the apparent power required to produce 500kW of real power is reduced to 505 KVA, a saving of 120KVA (at 415 Volts 3 phase, this is a reduction in switchboard current of 166 Amps per phase).

If the installation were being charged on a “KVA” demand basis then a real saving can be achieved eg. If the KVA demand charge is $5/KVA/Mth, then a reduction in electricity charges of $600/Mth would be available.