Power Factor

What is Power Factor?

Power factor is a measurement of how efficiently electrical energy is being consumed. It is measured on a scale of 0.00 to 1.00, and it represents the decimal percentage of the efficiency of the load. Therefore, a device with a power factor of 1.00 is a 100% efficient load (incandescent light bulb). A device with a power factor of 0.85 is an 85% efficient load (electric motor).

Why is low Power Factor a problem for the customer?

Due to the problems low power factor causes the utility, Commercial and Industrial customers with metered power demand greater than 50kW are charged when their power factor falls below 0.95. These charges can be minimal or in many cases substantial. Low power factor can also cause other electrical problems for the consumer including excessive voltage reduction and shortened equipment life.

Ultimately, Lewis County PUD reserves the right to discontinue service to any customer with a power factor of less than 0.8.

Why is low Power Factor a problem for the Utility?

While a low power factor does not result in the consumer using additional energy it does unnecessarily consume additional capacity of all the electric utilities facilities from the point of generation to the end user. Without proper steps taken to mitigate this problem the system would have to be rebuilt with additional capacity to accommodate the existing loads.

Additionally, the energy losses in transporting the power from generator to end user would increase, resulting in the need for additional generation resources.

How to determine if Power Factor Correction is needed.

For commercial and industrial customers with a demand greater than 50 kW the PUD monitors and records power factor each time the meter is read. If power factor falls below 0.95 a line item will appear on the bill showing what the power factor was for the billing cycle and the associated cost.

Most customers show concerns over the financial impact when the “Power Factor Adjustment” reaches a dollar amount equal to 10% of their total bill. However, we encourage any customer receiving a power factor adjustment charge to contact an electrician about correction. In some cases, mitigation costs can be recovered in as little as 6-12 months.

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