Description:
A Direct Online Starter (DOL starter) is an electrical device used to start and control electric motors, especially three-phase induction motors. It is one of the simplest and most commonly used motor starters, designed to connect the motor directly to the power supply. A DOL starter typically consists of a contactor, overload relay, and start/stop push buttons enclosed in a protective casing. It is widely used in small to medium-sized machines where high starting current does not cause major issues.

Operation:
The DOL starter operates by directly applying full supply voltage to the motor when the start button is pressed. This energizes the contactor coil, which closes the main contacts and allows current to flow to the motor, causing it to start running. At the same time, the overload relay monitors the current drawn by the motor. If the motor draws excessive current due to overload or fault conditions, the relay trips and disconnects the power to protect the motor from damage. Pressing the stop button de-energizes the contactor, opening the circuit and stopping the motor.