Question 213Electricity & Electronics - QMED

The correct answer is B) running current would increase and the motor would run hotter. When an induction motor is operated at 90% of its rated voltage, the magnetic flux in the motor will decrease, which in turn will increase the current required to produce the rated torque. This increased current will cause the motor to run hotter, as the copper losses in the windings will be higher. The starting torque may also decrease slightly due to the reduced voltage, but the running current will increase, leading to higher temperatures in the motor. The other options are incorrect because: A) the starting current would actually decrease due to the reduced voltage; C) the synchronous speed would remain the same, as it is determined by the frequency of the power supply; and D) the starting torque would decrease, not increase, with the reduced voltage.