What is the percent slip for a 6-pole, 60 Hz motor with a nameplate speed of 1170 RPM?

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Multiple Choice

What is the percent slip for a 6-pole, 60 Hz motor with a nameplate speed of 1170 RPM?

Explanation:
Slip is how much the rotor lags the synchronous speed, shown as a percent of the synchronous speed. For a 6-pole machine at 60 Hz, the synchronous speed is Ns = 120 f / P = 120 × 60 / 6 = 1200 rpm. With a rotor speed of 1170 rpm, the slip is s = (Ns − Nr)/Ns × 100% = (1200 − 1170)/1200 × 100% = 30/1200 × 100% = 2.5%. So the percent slip is 2.5%. If it were 0%, there would be no slip and no load; a larger difference (like 5% or 7.5%) would imply greater lag than is present here.

Slip is how much the rotor lags the synchronous speed, shown as a percent of the synchronous speed. For a 6-pole machine at 60 Hz, the synchronous speed is Ns = 120 f / P = 120 × 60 / 6 = 1200 rpm. With a rotor speed of 1170 rpm, the slip is s = (Ns − Nr)/Ns × 100% = (1200 − 1170)/1200 × 100% = 30/1200 × 100% = 2.5%. So the percent slip is 2.5%. If it were 0%, there would be no slip and no load; a larger difference (like 5% or 7.5%) would imply greater lag than is present here.

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