Consider the following statements about characteristics of reluctance motor and select the suitable combination of correct choices.

a. Reluctance motors cannot accelerate high inertia loads to the synchronous speed.

b. Reluctance motors can accelerate high inertia loads to the synchronous speed.

c. Reluctance motors are cheaper than any other kind of synchronous machines.

d. Reluctance motors have constant speed characteristics.

The correct answer is option 2): (a, c and d are correct)

Concept:

Reluctance motor:

• The stator of the reluctance motor has the main and auxiliary winding
• The stator of the single-phase reluctance and induction motor are the same
• The rotor of a reluctance motor is a squirrel cage with some rotor teeth removed in certain places to provide the desired number of salient rotor poles
• The rotor needs no dc excitation It is a self-starting machine and it rotates with constant speed It can operate on ac supply only
• Reluctance motors can deliver very high-power density at a low cost, making them ideal for timing devices and control apparatus.
• The other applications of reluctance motors are Signalling devices Recording instruments Phonographs Analog electric meters
•  These motors cannot accelerate high-inertia loads to synchronous speed.The pull-in and pull-out torques of such motors are weak.
• Reluctance motors have poor efficiency and torque.
• Reluctance motors have low power factor.
• Reluctance motors are cheaper than any other kind of synchronous motors.