A hysteresis motor is a synchronous motor without salient (or projected) poles and without
dc excitation which starts by virtue of the hysteresis losses induced in its hardened steel secondary
member by the revolving filed of the primary and operates normally at synchronous speed and runs on
hysteresis torque because of the retentivity of the secondary core.
It is a single-phase motor whose operation depends upon the hysteresis effect i.e., magnetization
produced in a ferromagnetic material lags behind the magnetizing force.