What is Cogging and Crawling?


The rotor of a squirrel cage motor sometimes refuses to start at all, particularly when the voltage is low. This happens when the number of stator teeth is equal to the number of rotor teeth and is due to the magnetic locking (cogging) between the stator and rotor teeth


Induction motors, especially the squirrel cage type, sometimes exhibit a tendency to run stably at speeds as low as one-seventh of their synchronous speed Ns. This phenomenon is known as crawling of an induction motor