Saving money with good power factor

What is power factor and what do I do about it?

Power factor is the ratio of real power flowing to the load divided by the apparent power in the circuit. It is a dimensionless number in the closed interval of -1 to 1.  It is the ratio between Watts and VARs consumed (normally kW and kVAR). In an electrical power system, loads with low power factor (such as motors, fluorescent lamp ballasts, lightly loaded transformers, and other devices that generate a magnetic field) draw more current for the same amount of useful power as a load with a higher power factor.

Lagging power factor is penalized by utilities. Low (lagging) power factor draws more current than a load with a higher power. Utilities must use larger conductors and other equipment when their system has a low power factor.

Low power factor appears on a utility bill as a penalty or surcharge normally applied when a customer’s average power factor dips below 0.90 for a given period.

Power factor correction capacitors can be added to a system to correct the power factor and return it to a non-penalty value.

Leading power factor is a situation where too much capacitance is applied. High (leading) power factor can cause overvoltage and can amplify existing system harmonics.

Automatic Power Factor Correction Systems detect the correction required and dynamically add and remove capacitors or inductors from the system to achieve the target power factor.

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How does BC Hydro penalize poor power factor?

BC Hydro customers on the Medium General Service or Large General Service tariff may be subject to surcharges if their power factor dips below 90% in a billing period.

POWER FACTOR SURCHARGE
90% – 100% None
88% – 90% 2%
85% – 88% 4%
80% – 85% 9%
75% – 80% 16%
70% – 75% 24%
65% – 70% 34%
60% – 65% 44%
55% – 60% 57%
50% – 55% 72%
< 50% 80%

Where will I see if I have a penalty?

Check line number 8 your BC Hydro utility statement. If your power factor is 89% or lower or you have a non-zero dollar value in the Power Factor row, you may be needlessly paying a surcharge!

PF must be >90% or you will be charged!

Email a copy of your usage statement showing a surcharge to [email protected] and our engineering team would be glad to make a capacitor sizing calculation for you. Payback on a power factor correction capacitor install can be as fast as 3 months!