Question 531Electricity & Electronics - Assistant Engineer

70% to pass

A six-pole three-phase squirrel-cage induction motor operating at 60 Hz is running at 1155 rpm. What is the percentage slip in this case?

A3.0%
B3.75%
C4.25%
D5.0%
AI Explanation

The correct answer is B) 3.75%. To calculate the percentage slip, we can use the formula: Slip (%) = (Synchronous Speed - Actual Speed) / Synchronous Speed x 100. The synchronous speed of a 6-pole, 60 Hz motor is given by the formula: Synchronous Speed (rpm) = (120 x Frequency) / Number of Poles, which in this case is 1200 rpm. The actual speed of the motor is given as 1155 rpm. Plugging these values into the slip formula, we get: Slip (%) = (1200 - 1155) / 1200 x 100 = 3.75% The other options are incorrect because: A) 3.0% is too low C) 4.25% is too high D) 5.0% is too high

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