A synchronous reluctance motor on over-load runs as
Right Answer is:
A synchronous reluctance motor on over-load runs as an Induction motor
In a synchronous reluctance Motor when the stator is energized. the rotor accelerates as a squirrel-cage induction motor. As the rotor approaches synchronous speed, the slip is very small and the rotating flux of the stator moves slowly past the salient poles of the rotor. At some critical speed, the low-reluctance paths provided by the salient poles cause them to snap into synchronism with the rotating flux of the stator. When this occurs, the slip is zero, induction-motor action ceases, and the rotor is pulled around by simple magnetic attraction called reluctance torque.
Reluctance torque increases with increasing torque angle, attaining its maximum value at δ = 45°.
If the shaft load is increased to a value that causes δ > 45°, the increased length of the magnetic flux path between the centerline of the rotating staler poles and the centerline of the corresponding rotor poles causes a decrease in flux and hence a decrease in magnetic attraction. In effect, the flux lines are “over-stretched,” the rotor falls out of synchronism, and the machine runs as an induction motor at a slip speed determined by the amount of overload.