A 30 MVA, 15 kV alternator will have a per phase nominal impedance of ______

Question

RRB Paper · Accepted Answer

To calculate the per-phase nominal impedance of an alternator, we can use the formula:

Z = V² / S

where Z is the per-phase nominal impedance, V is the rated voltage, and S is the rated apparent power.

Given data:

Rated power = 30 MVA = 30,000,000 VA Rated voltage = 15 kV = 15,000 V

Using the formula:

Z = (15,000 V)² / 30,000,000 VA Z = 7.5 ohms

Therefore, the per-phase nominal impedance of the alternator is 7.5 ohms.

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