DOL starter is a device consisting of main contactor, protective devices and overload relay which is used for motor starting operations. In a direct online starter, the motor stator windings are directly connected to the main supply. These types of starters are used in small motors.
Following is the basic wiring diagram of a DOL (Direct Online Starter).
The DOL starter is made of a circuit breaker or MCCB or fuse, an overload relay and contactor or coil. The circuit breaker is used for protection against short circuits while the overload relay protects the motor from overloading. The contactor is used for starting and stopping the motor where the green and red buttons are connected
What is the typical starting current for an asynchronous motor with a DOL starter?
Starting current is about 5 to7 times the normal running current, and 1.5 times the rated
torque.