Power factor

Definition

Power factor is the ratio of real power (P) to apparent power (S) in an AC circuit. It indicates how effectively the electrical power is being converted into useful work output.

5 Must Know Facts For Your Next Test

1. Power factor ranges from 0 to 1, where a power factor of 1 indicates that all the power is effectively used.
2. It can be calculated using the formula $\text{Power Factor} = \cos(\phi)$, where $\phi$ is the phase angle between voltage and current.
3. A low power factor indicates poor efficiency and results in higher energy losses in the system.
4. Inductive loads (like motors and transformers) usually cause a lagging power factor, while capacitive loads cause a leading power factor.
5. Improving the power factor can reduce electricity costs and improve system stability.

Review Questions

• What is the formula for calculating power factor?
• How does a low power factor affect an electrical system?
• What types of loads typically cause a lagging power factor?

Related terms

Real Power:

The actual amount of power consumed by a circuit to perform useful work, measured in watts (W).

Apparent Power: The product of the root-mean-square (RMS) values of voltage and current, representing total power flow in an AC circuit, measured in volt-amperes (VA).

Reactive Power: $Q$ represents the imaginary component of apparent power that does not perform any useful work but sustains electric and magnetic fields, measured in volt-amperes reactive (VAR).