Exams › GATE › Technical

A three-phase, three-stack variable reluctance step motor has 20 poles on each rotor and stator stack. The step angle of this step motor is

1. 3°
2. 6°
3. 9°
4. 18°

Correct answer: 6°

Solution

For a variable reluctance step motor, the step angle is determined by the pole pitch mismatch between stator and rotor. Using the standard relation for a three-stack, three-phase motor with 20 poles on each stack gives a step angle of 6°.

Related GATE Technical questions

• The following arrangement consists of an ideal transformer and an attenuator that attenuates by a factor of 0.8. An AC voltage $V_{WX}=100$ V is applied across $WX$ to get an open-circuit voltage $V_{YZ}$ across $YZ$. Next, an AC voltage $V_{YZ}=100$ V is applied across $YZ$ to get an open-circuit voltage $V_{WX}$ across $WX$. Then, $V_{YZ}/V_{WX}$ and $V'_{WX}/V'_{YZ}$ are respectively.
• In a transformer, zero voltage regulation at full load is
• The DC motor that can provide zero speed regulation at full load without any controller is
• A voltage-source inverter is used to control the speed of a three-phase, 50 Hz squirrel-cage induction motor. Its slip for rated torque is 4%. The flux is maintained at the rated value. If the stator resistance and rotational losses are neglected, then the frequency of the impressed voltage required to obtain twice the rated torque at starting should be:
• A three-phase synchronous motor connected to AC mains is running at full load and unity power factor. If its shaft load is reduced by half, with field current held constant, its new power factor will be
• A single-phase 50 kVA, 250 V/500 V two-winding transformer has an efficiency of 95% at full load, unity power factor. If it is reconfigured as a 500 V/750 V autotransformer, its efficiency at its new rated load at unity power factor will be

⚔️ Practice GATE Technical free + battle 1v1 →