What is the main function of a motor start relay in a single-phase motor?

The main function of a motor start relay in a single-phase motor is to temporarily provide power to the start winding until full speed is reached. This process is essential because single-phase motors require an additional winding and circuit (the start winding) to initiate motion. The start relay activates this winding during startup, allowing the motor to gain the necessary speed to operate effectively.

Once the motor reaches a predetermined speed, the relay disengages the start winding, preventing it from drawing unnecessary current and potentially burning out. This action is crucial for the efficient operation and longevity of the motor. The relay ensures that the additional power provided to the start winding is only utilized during the initial phase of startup, making it an integral component in the functioning of single-phase motors.