Electric Power in Electrical Engineering

The Electric Power or Energy

In simple words, It is the rate at which electrical energy consumed or absorbed or transferred by an electrical circuit. Electric Power or Electrical energy can be provided by batteries or Electric Generators & Power can be consumed by the load connected to the circuit. In other words, Electric Power is also defined as the product of voltage and current in an electric circuit. The SI unit of Electric Power is watt and which means one joule per second. For the measurement of electric power or connected load, we used the watt-meter.

The electrical power measured in KWh in energy meter in which Units counts as per connected load. If 1000 watts consumed in one hour by connected load then it will be 1 unit in energy wattmeter. We can say 1 KWh is equal to 1 unit.

There are three types of Electric Power:

 (i) Actual or Real Power 
(ii) Apparent Power
(iii) Reactive Power

(i) Actual or Real Power:  Actual power is the product of the voltage applied, a current flowing, and power a factor of the circuit.

The actual power has the maximum value when the phase difference between voltage and current is 0° i.e. when p.f. 1 and minimum value when the angle between voltage and current vectors is 90° i.e. when p.f. = 0.

The actual power is also known as Active power and is expressed in Watts (W) or Kilowatts (KW).

1 KW = 1000 W

(ii) Apparent Power: Apparent power is defined as the product of voltage and current

i.e. Apparent Power V. I

This is a special case of power when the power factor is equal to unity.

Apparent power is expressed in Volt-Ampere (VA) or Kilo-Volt Ampere {KVA)

1KVA = 1000 VA

(iii) Reactive Power: The product of Voltage, Current and and sine of the angle between voltage current is called Reactive power i.e. Reactive power = VI sin o

The Unit of Reactive Power is VAR or KVAR

1KVAR = 1000 VAR