Synchronous Motor MCQ Part 7

Multiple choice questions on Synchronous motor with brief explanatory answers.

Synchronous Motor MCQ Part 7

The pull-out torque of a 3 phase synchronous motor varies as

The pull-out torque of a synchronous motor varies as:

1. 1/V
2. Voltage
3. Square of voltage
4. Square root of voltage

Correct answer: 2. Voltage

Explanation:

The pull-out torque of a synchronous motor is mathematically defined as:

The steady-state speed of the motor is constant from no load to the maximum torque that the motor can supply: which is called the pull-out
torque.

The maximum or pull-out torque of motor is given by the following relationship:

τ = (3 V_ϕ.E_A)/(ω_m.X_s)

From above equation one can understand that the pull-out torque of motor varies as the voltage.