What is power factor?

Power factor (PF) is the ratio of real power (kW) to apparent power (kVA). It ranges from 0 to 1, where 1 (unity) means all energy is doing useful work. A PF below 1 indicates reactive power is present, causing extra current to flow without doing useful work.

What is the difference between leading and lagging power factor?

A lagging power factor occurs when the load is inductive (motors, transformers) — current lags behind voltage. A leading power factor occurs when the load is capacitive — current leads voltage. Most industrial loads are inductive with a lagging power factor.

How is power factor related to phase angle?

Power factor equals the cosine of the phase angle (theta) between voltage and current: PF = cos(θ). A phase angle of 0° gives PF = 1 (unity), while 90° gives PF = 0.

What is a good power factor for industrial systems?

Most utilities require a power factor of 0.90 or higher. Below this threshold, penalty charges may apply. A power factor of 0.95 or above is generally considered excellent for industrial applications.

What is reactive power and why does it matter?

Reactive power (kVAR) is the power stored and released by inductive or capacitive components in a circuit. It does no useful work but causes extra current to flow, increasing conductor losses and reducing system capacity. Capacitor banks are used to cancel inductive reactive power and improve power factor.

Can power factor exceed 1?

No. Power factor is always between 0 and 1 (inclusive). A value greater than 1 indicates incorrect measurements or calculation errors. By definition, apparent power (kVA) is always greater than or equal to real power (kW).

What is the power factor of a 10 hp motor?

A typical 10 hp (7.5 kW) induction motor runs at a power factor of about 0.84 to 0.86 at full load, falling toward 0.5 at light load. Check the motor nameplate for its rated PF, then use this calculator to size correction capacitors.

Power Factor Calculator

Enter voltage, current, and phase angle (or any two power values) to instantly calculate real power, reactive power, apparent power, and power factor.