In DOL starting, the motor is connected directly to the power supply without any external devices such as soft starters or variable frequency drives. The DOL starting method is simple and cost-effective, making it the most common method used for starting small and medium-sized motors.
The DOL starting method consists of a contactor, an overload relay, and a start and stop button. When the start button is pressed, the contactor closes, and the motor is connected directly to the power supply. The overload relay protects the motor from overcurrent and overheating. The stop button is used to disconnect the motor from the power supply.
The advantages of DOL starting are its simplicity, low cost, and high efficiency. It is suitable for starting small and medium-sized motors that do not require speed control. However, DOL starting can cause a high inrush current, which can result in voltage dips and cause disturbances to other electrical equipment connected to the same supply. Additionally, DOL starting can cause mechanical stresses on the motor and the driven machinery due to the high starting torque.
In summary, DOL starting is a simple and cost-effective method of starting three-phase induction motors. It is suitable for small and medium-sized motors that do not require speed control. However, it can cause voltage dips and mechanical stresses on the motor and driven machinery. Therefore, it is important to consider the specific requirements of the motor and driven machinery when selecting the starting method.