What is the leading power factor

Power factor

The power factor is defined as the ratio of active power (P) and volt amperes. Real power is the actual power assumed in an AC circuit, while volts amps is the apparent power produced in the circuit when the waves of voltage or current are out of phase.

For sine waveforms, the power factor is the cosine of the angle (phase angle) between voltage and current.

Equation (1) shows that the current is affected by the power factor. Therefore, for a given power P due to the load, the current I consumed by the load changes inversely as the load power factor cos. Thus, a given load will require more current at a low power factor than at a high power factor.

Disadvantages of the low power factor

The undesirable effect of operating a low load at a low power factor is due to the high current required for a low power factor. The main disadvantages of the low power factor are

  • The equipment requires a higher current, which increases the economic cost of the equipment.
  • With a low power factor, the current is high, which leads to high copper losses in the system and therefore reduces the efficiency of the system.
  • A higher current created a large voltage drop in the device. This leads to poor voltage regulation.

Because both capital and operating costs are increased, the system is uneconomical to operate at a low power factor (whether it is a lag or a leading value) from the supplier's point of view.

Causes of low power factor

The common reason for the low power factor is because of the inductive load. The current in the inductive load lags behind the voltage. The power factor therefore remains behind. The main inductive loads that are responsible for the low power factor are the three-phase induction motors (which operate with a power factor of 0.8), transformers, lamps and welding machines operate with low power factors. Power factor improvement methods are used to improve the value of the power factor in an energy system.