The shaft torque of a dc motor is less than the electromagnetic torque because of
A. mechanical losses.
B. hysteresis losses.
C. ohmic losses.
D. eddy current losses.
Answer: B
Share your understanding of this question with the correct explanation.
The shaft torque of a DC motor is less than the electromagnetic torque because of hysteresis losses.
Hysteresis losses occur in the core material of the motor due to the continuous reversal of magnetic flux during operation. These losses result in the conversion of electrical energy into heat within the core material, leading to a reduction in the overall efficiency of the motor.
When the electromagnetic torque is generated in the motor, it is partially lost as hysteresis losses in the core. As a result, the torque available at the motor shaft, known as the shaft torque, is lower than the electromagnetic torque produced by the interaction of the magnetic fields.
It’s worth noting that mechanical losses, such as friction and windage losses, can also contribute to the difference between electromagnetic torque and shaft torque. However, in the context of the given options, the most appropriate answer is B: hysteresis losses.
Therefore, the correct answer is B: hysteresis losses. Hysteresis losses in the core material of a DC motor result in a reduction of the shaft torque compared to the electromagnetic torque generated by the motor.