A 3 phase squirrel cage induction motor is a type of three-phase induction motor which functions based on Faraday's law of electromagnetic induction. It is called a 'squirrel cage' motor because the rotor inside of it – known as a 'squirrel cage rotor' – looks like a squirrel cage.
The most common method of starting squirrel cage three-phase motors is across the line (direct-on-line). Some applications require limiting the motor starting current and/or torque to reduce the stress on the electrical and mechanical systems.