A 3,5kW 240V single-phase motor draws 22,5A from the supply while operating at full load and efficiency of 90°. Calculate

a) The power factor at which the motor is operating
b) The phase angle at which the motor is operating

1 answer

a) To calculate the power factor, we can use the formula:

Power factor = Real Power / Apparent Power

The real power can be calculated using the formula:

Real Power = Input Power x Efficiency

The input power can be calculated using the formula:

Input Power = Voltage x Current

Therefore, Real Power = 240V x 22.5A = 5400W

The apparent power can be calculated using the formula:

Apparent Power = Voltage x Current

Therefore, Apparent Power = 240V x 22.5A = 5400VA

Now we can calculate the power factor:

Power factor = Real Power / Apparent Power = 5400W / 5400VA = 1

Therefore, the power factor at which the motor is operating is 1.

b) To calculate the phase angle, we can use the formula:

Phase angle = arccos(Power factor)

Therefore, Phase angle = arccos(1) = 0°

Therefore, the phase angle at which the motor is operating is 0°.