If the power factor of 500 KVA, 21 KW, 3-phase star connected alternator is increased from its initial value, then the efficiency of the synchronous generator will _______.

Effect of Power Factor on Efficiency of a Synchronous Generator:

The efficiency of a synchronous generator is defined as the ratio of its output power to its input power. It is given by the formula:

η = (P_out / P_in) × 100%

Where,

• P_out = Output power (in kW)
• P_in = Input power (in kW)

The power factor (PF) of a synchronous generator is the cosine of the phase angle (ϕ) between the voltage and the current. It affects the real power (P) delivered by the generator, which is given by:

P = S × PF

Where,

• S = Apparent power (in kVA)
• PF = Power factor

Given Data:

• Apparent power (S) = 500 kVA
• Output power (P_out) = 21 kW

When the power factor is increased, the real power (P) output of the generator increases for the same apparent power. This is because:

P = S × PF

As PF increases, P increases.

Since the real power output (P_out) increases while the input power remains relatively constant, the efficiency (η) of the generator will increase.

Conclusion:

If the power factor of the 500 kVA, 21 kW, 3-phase star connected alternator is increased from its initial value, the efficiency of the synchronous generator will increase.

Therefore, the correct option is:

1) Increase