Minor loop

In a hysteresis motor the magnetic states (B/H relations) trace a major loop and many minor loops; that is, before the rotor speed reaches the rotating field speed, the B/H operating point traces on the major loop altering magnetic polarization, but after the speed has reached synchronism, the operating point travels on minor loops corresponding to the load torque at each part of the ring. Minor loops cause increase in hysteresis loss and torque. However, in a hysteresis brake minor loops contribute to increased retarding torque.