Free Tool

Generator Synchronous Speed Calculator

Calculate a generator's synchronous speed in revolutions per minute (rpm) from the grid frequency and pole count, or leave any field empty to calculate it from the other two — based on the formula N = 120f / P.

Enter any two values and leave the third field empty, then click Calculate to find the missing value.

The number of poles must be an even integer (2, 4, 6, ...). An approximate pole-count result is rounded to the nearest even integer.

Equation Used

N (rpm) = 120 × f (Hz) / P

Where N is the synchronous speed in revolutions per minute, f is the grid frequency in hertz, and P is the number of poles (always an even number).

Worked Example

A generator with four poles (P = 4) connected to a grid with a frequency of 50 Hz:

N = 120 × 50 / 4 = 1500 rpm

This means the generator must rotate at exactly 1500 revolutions per minute to produce a synchronous frequency of 50 Hz.

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