There are two types of current. These currents are direct current and alternating current. Today’s, the electrical energy generated, transmitted and distributed in the form alternating current. When, we talk about alternating current, the term of power factor immediately comes to mind. Most of the loads are inductive in nature. The inductive loads have low lagging power factor. Low power factor causes an increase in current demand. This results increase in losses on the power system. In this article, we will discuss about power factor and power triangle.

Power Factor

The smallest cosine of the angle between voltage and current in an AC system, termed as power factor or pf. It denotes by cosΦ. 

There are three types of loads. These loads are inductive load, capacitive load and resistive load. If the load is inductive, the current lags behind the voltage and power factor is referred to as lagging. In case of capacitive loads, current leads the voltage and pf is referred as leading. However, in resistive load power factor is said to be unity.

Consider a phasor diagram of inductive load. Inductive load takes a lagging current I from the supply voltage V, that is IcosΦ. This component is known as ‘wattful’ component. Reactive component that is which in quadrature with V, that is IsinΦ . It refers to ‘wattless’ or ‘idle’ component. Pf(CosΦ) depends on reactive component of the current. If the reactive is small and hence CosΦ will be high. Therefore, a circuit having small reactive current will have high Power factor and vice versa. 

Power Triangle

The circuit draw a current of I by applying voltage V. Suppose, that current I lags behind the applied voltage V.  The three powers drawn by the circuit are as follows:-

power factor and power triangle
power triangle

Apparant Power

It is product of r.m.s. voltage  V and current I, that is VI. It represents in VA or KVA.

Active Power

It products of Voltage V, current I and cosΦ, that is VIcosΦ.Hence, it represents in watts or KW. It is useful for working of system. Active power actually dissipates in the circuit.

Reactive Power

VIsinΦ refers as reactive power, represents in VAR or KVAR. This power develops inductive reactance in the circuit.