Motor Power Calculation: Understanding Reactive Power

What is the reactive power drawn by a motor if the 20 hp motor draws an apparent power of 20 kva?

Reactive power is a component of electrical power that represents the energy exchange between reactive elements, such as inductors and capacitors, in an alternating current (AC) circuit. It is measured in units called volt-ampere reactive (VAR).

How can we calculate the reactive power drawn by the motor based on the given data?

Calculation of Reactive Power for the Motor:

Given data: Apparent Power (S) = 20 kVA

Since the power factor is not provided, we will assume a common power factor of 0.85 for motors.

Reactive Power (Q) = Apparent Power (S) x sine(arccos(power factor))

For power factor 0.85:

Reactive Power (Q) = 20 kVA x sine(arccos(0.85))

Calculating the reactive power:

Reactive Power (Q) = 20 kVA x sine(30.58 degrees)

This calculation will give us the estimated reactive power drawn by the motor.

Reactive power is crucial in understanding the full power consumption in electrical systems and ensuring efficient operation.

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