Electric Power:
- In terms of physics, power is defined as the rate of doing work & Rate of energy transferred per unit of time. Power is also defined as how fast work is done. In terms of electrical engineering, power is defined as the product of voltage and current.
P=VI
Where, V is the voltageI is the current
- In the case of AC, power also depends on power angle, ie. Active power & Reactive Power.
- In the case of AC power can be divided into 3 types, That is shown below.
- To know the active, reactive and apparent power we must have to understand that. Let be explained with an example as shown in the figure below.
- In the above figure, a horse pulling a wagon which is placed on the track. When the horse pulled the wagon at some angle of its own direction the wagon change its own position in its own direction as shown in the figure. After pulling the wagon by horse the wagon comes to point P.
- Here the power required for moving the wagon from the initial point to at point P is Real (Active power). The total effort provided by the horse is Apparent Power and the waste power which is the act between the horse and point P is reactive power.
Now we have to determine the Active, Reactive and Apparent power by power triangle as shown below.
The figure is shown above the right angle triangle.
Apparent power = VI
Now by trigonometry,
Active power = VIcosϕ
Reactive power = VIsinϕ
ACTIVE POWER:
- It is measured in kilo-watt(KW), It is the work provided for motion, torque, force etc whatever system is required.
REACTIVE POWER:
- It is measured in kilovolt-amperes-reactive(KVAR), it is not useful work.
APPARENT POWER:
- Normally measured in Kilovolt-amperes (KVA), the real power and reactive power together make up apparent power.