Power Factor

Who doesn’t love power? Everybody wants it; few understand it.

Power factor is a very important parameter that should be understood not only for fluorescent and HID light sources, but also for LED lamps and fittings. It is the capacity of lamps to output active power.

What is Power Factor?

A measure of how effectively electrical power is being used, power factor is the ratio of the real power to apparent power and represents how much real power electrical equipment utilises.

It is always between 0.0 and 1.0, and commercial installations with a low power factor and on a kVA tariff will have a greater energy consumption than a similar installation with a high power factor.

How Much Energy Is Really Being Used?

Power is the measure of energy transmission rate; it is the product of voltage (V) and current (A) in direct current (DC) circuit.

Power Factor (PF)   =

Active Power (W)

Apparent Power (VA)

PF = > 0.0 / < 1.0

However, in an alternating current (AC) circuit, it is much more complicated. AC power contains three components:

  • Real (Active) Power - measured in watts
  • Apparent Power - measured in volt-amperes
  • Reactive Power - measured in reactive volt-amperes

A Cup of Power

In the video above, we explain this in a simplified manner by using a cup of white coffee as an example.

  • The coffee cup represents active power.
  • The milk represents reactive power.
  • The entire contents within the cup represent the apparent power.

The more milk in the cup, the lower the strength of the coffee. In other words, the more reactive power, the less efficient the lamp!

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