SOLUTION

Starting winding of a single-phase motor of a refrigerator is disconnected from the circuit by means of a Magnetic Relay.

Electromagnetic relay in Split phase Induction motor

Starting relay

The function of starting relay provided in the refrigerator is to start the split-phase induction motor by connecting the auxiliary winding or starting winding across the main supply in addition to the main winding at the time of starting. This helps to make the split-phase induction motor as the self-induction motor is unable to start.

During starting the relay picks up due to the high starting current and connects the auxiliary winding in the circuit. When the motor reaches normal speed, current drops to normal value, and the electromagnetic relay is dropped and therefore the auxiliary winding gets disconnected from the supply.

In Refrigerator the motor is a single voltage non-reversible type that means the direction cannot be reversed unless the motor is taken apart and the leads of the starting winding are reversed. Therefore instead of a centrifugal switch magnetic relay is used to disconnect the start winding when the motor reaches 75% of its rated speed.