what is cogging and crawling

Answer Posted / shweta gupta

When the voltage is low, the rotor of Squirrel-Cage motor
refuses to start at all. This happens when the number of
stator teeth S1 is equal to the number of rotor teeth S2
and is due to the magnetic locking between the stator and
rotor teeth.This is why this phenomenon also known as teeth-
locking or cogging.

The Squirrel- Cage type motor sometimes exhibit a tendency
to run stably at speeds as low as one-seventh of their
synchoronous speed Ns. This phenomenon is known as Crawling.

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