The efficiency of the reluctance motor is around
Right Answer is:
70 to 80%
The reluctance motor is a cheap and reliable synchronous motor that requires no d.c. excitation. Commercial motors are available in ratings of 20 kW or more.
The machine has a 3-phase stator winding similar to that of an induction motor, and a rotor without windings.
For a given frame the output is about 70 to 80% of that of an induction machine, and the motor has slightly lower efficiency.
For a motor of 5 kW rating typical data are:
Reluctance ratio, 3 − 6;
Power factor, 0.6 − 0.75 lagging
Pull-out torque, 2 − 2.5 p.u
Pull-in torque, 0.9 − 1.2 p.u.
Motors with change-speed windings are possible, and motors can be built for variable frequency (2 − 200 Hz) but these are liable to instability at the lower end of the range.