Attention all large use electricity customers – what’s your power factor?
Most big businesses in Western Australia which consume at least 1 million kWh (1 GW) of electricity per year are not aware their power factor could be costing tens of thousands of dollars in network charges every year, and this can be prevented.
Power Factor (PF) is a measure of how effectively incoming power is used at your site and is the ratio of real (working) power to apparent (total) power. PF is described as a value between -1 and 1 and can be either inductive (lagging) or capacitive (leading). A power factor of 1 means all of the supplied power is used for productive work. For example, a PF of 0.7 means 70% of power is used effectively and 30% is being wasted, resulting in additional network charges.
Real power (kW) performs useful, productive work (like powering equipment). It is also referred to as actual power, true power, active power or working power.
Reactive power (kVAR) is used to provide the voltage levels needed for real power to do useful work. It is needed by some equipment (e.g. transformers, motors and relays) to produce a magnetic field to enable real work to be done. However, you don’t see any result for its use.
Apparent power (kVA) is the vector sum of real power (kW) and reactive power (kVAR) and is the total power supplied through the power mains that is required to produce the relevant amount of real power for the load.
To help understand, we can use a well-known analogy of a glass of beer. The thirst-quenching liquid portion of the beer represents real power (kW). The non-drinkable portion, the froth, represents reactive power (kVAR).
The total content of the beer glass (KVA) is the sum of kW (the beer) and kVAR (the froth).
Therefore, for a given power supply (kVA):
- The more froth you have (the higher the percentage of kVAR), the lower your ratio of kW (beer) to kVA (beer plus froth). Therefore, more froth equals lower power factor.
- The less froth you have (the lower the percentage of kVAR), the higher your ratio of kW (beer) to kVA to kVA (beer plus froth) and the better your power factor.
- As your froth (or kVAR) approaches zero, your power factor approaches 1.0.
Power conditioning – the solution to poor power factor
A low power factor, usually under 0.8, equates to significant network charges that are passed through by Western Power. A customer with a PF of 0.8 is paying approximately 20% more in network charges.
Installing power conditioning equipment to machinery and equipment can lead to big savings. Here is a real example from one of our customers:
The rules are currently being reviewed to allow max kVA levels to be reset and let customers start saving immediately from power conditioning. Importantly, inefficiencies shorten the life span of machinery and equipment. Improving PF will also improve the life of capital equipment.
What is your power factor? Contact us today on 6245 6493 to find out.