# Difference between Leading and Lagging Power Factor

DifferencesDigital ElectronicsElectronics & Electrical

In electrical engineering, the power factor of an AC system is the expression of energy efficiency. The power factor (PF) is defined as the ratio of active power (measured in Watts) to the apparent power (measured in VA).

The power factor expresses the ratio of true power which is used in an AC circuit to the total power delivered to the circuit. Mathematically, the power factor can be expressed using the following formula −

$$\mathrm{Power \: factor \, \mathrm{=}\,\frac{Active \: power}{Apparent \: power}}$$

There are two major terms are associated with the power factor of an AC circuit viz. Lagging and Leading. These two terms show the relation between the current and voltage in the circuit.

## What is Leading Power Factor? The leading power factor can also be described as the load current that attains its peak value upto 90° ahead of the voltage. A leading power factor also means that the same voltage across the load terminals can be maintained with a lower internal induced voltage. An inductive load is used to correct the leading power factor.

## What is Lagging Power Factor?

When the load current lags behind the supply voltage, then the load is said to have lagging power factor. In other words, power factor of the load is said to be lagging if the current waveform is behind the voltage waveform. The lagging power factor of the load signifies that the load is inductive and it will consume the reactive power. The lagging power factor can also be described as the load current that attains its peak value upto 90° later of the voltage. In order to correct the lagging power factor capacitive loads are employed.

## Difference between Lagging and Leading Power Factor

The following table shows the key differences between the lagging power factor and leading power factor.