*Apparent power is defined as the product of current time voltage passing through an AC circuit.***The basic formula to calculate apparent power in any circuit is:**

S = VI

where S = Apparent power measured in VA (volt-amperes)

V = Voltage

I = Current

Also learn top 100 Basic Electrical Engineering Formulas

### Industrial unit

Unit VA is very small for heavy equipment and practically kVA is used instead of VA.

Where S (kVA) = VI / 1000

In single and three phase circuit the kVA formulas are:

**Single phase kVA = [V * I] / 1000**

**Three phase kVA = [E * I * 1.73] / 1000**

Example 1: Find the apparent power in kVA drawn by a 200 V single phase generator having 2 Amps current passing through it.

Solution: kVA = 200 * 2 / 1000 = 0.4 kVA

Example 2: Find the current drawn by 500 kVA transformer @ rated voltage 5 kV.

Solution: By cross multiplication:

I = (500 * 1000) / (1.732 * 5k) = 57.73 Amps

Other useful formulas:

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