DOL Starter (Direct On Line Starter)
DOL Starter (Direct On Line Starter) Diagram & Working Principle What is DOL Starter? A DOL starter (or Direct On Line starter or across the line starter ) is a method of starting of a 3 phase induction motor . In DOL Starter an induction motor is connected directly across its 3-phase supply, and the DOL starter applies the full line voltage to the motor terminals. Despite this direct connection, no harm is done to the motor . A DOL motor starter contains protection devices, and in some cases, condition monitoring. A wiring diagram of a DOL starter is shown below: Since the DOL starter connects the motor directly to the main supply line, the motor draws a very high inrush current compared to the full load current of the motor (up to 5-8 times higher). The value of this large current decreases as the motor reaches its rated speed. A direct online starter can only be used if the high inrush current of the motor does not cause an excessive voltage drop in the supply circuit. If