Question 261Electricity/Electronics - Assistant Engineer70% to pass
Which of the listed motors will operate at the highest RPM, assuming that each operates at the same frequency?
AI Explanation
The correct answer is A) A four-pole synchronous motor under normal load.
Synchronous motors operate at a fixed speed that is directly proportional to the frequency of the power supply and the number of poles in the motor. For a four-pole synchronous motor, the speed is determined by the formula: Speed (RPM) = (120 x Frequency) / Number of Poles. Assuming the same frequency, a four-pole synchronous motor will operate at a higher RPM compared to a six-pole synchronous motor or induction motors, which have variable speeds depending on the load.
The other options are incorrect because: B) A four-pole induction motor under no load would operate at a lower RPM than a synchronous motor, C) A six-pole synchronous motor under normal load would operate at a lower RPM than a four-pole synchronous motor, and D) A six-pole induction motor under full load would operate at a lower RPM than a four-pole synchronous motor.
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