Hello friends, today I am going to tell you DOL Starter Scheme and Wiring Diagram: If you also want to know, then keep reading this article completely.
DOL Starter Scheme and Wiring Diagram
Two types of schematics and wiring diagrams are drawn for any electrical circuit. The contactor control circuit is used to control the motor, which is as follows.
A starter is required to start a three-phase induction motor. Low power motors can be supplied voltage directly. Starters are needed to start the motor, shut it down, automatically shut off when overloaded, the motor does not start again after the supply is turned off, run the motor in a protective way, etc. In this type of starter, the supply to the motor is given directly through the contactor. In this starter, the motor gets full line voltage, and there is no control on the starting current of the motor. This starter is used only for overload and short circuit protection. D.O.L. for the electric motor The schematic diagram of the starter’s control circuit and the complete wiring diagram is shown in the figure.
The combination of a 3 phase supply, main switch, contactor, and a thermal overload relay to the motor is described through a schematic diagram. As soon as the ON push button is pressed to start the motor, the control supply, moving forward from the control fuse, meets the coil A of the relay through the contact of O.L.R. (Over Load Relay). The contactor pick-up is done as soon as the supply is received, which closes the main contacts of the contactor, and 3 phase supply gets to the motor, which starts the motor.
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When the contactor is picked up, its auxiliary contacts also change their position, such as the contact which is NO (Normally Open) is closed and the one which is N.C. (Normally Close) becomes open. Here only one auxiliary contact c is used. It is clear from figure (a) that it is installed parallel to the ON push button. Hence, even when the ON push button is pressed and released, the power supply through auxiliary contact c continues to be supplied to coil A of the contractor, and the main contractor remains in the pick-up position. Due to this, the motor keeps running. When the motor is to be turned off, the OFF push button is pressed, which breaks the supply of contactor coil A, resulting in its drops, and the contactors are opened, which stops supply to the motor and stops the motor. It becomes Along with the power contacts; the auxiliary contact c is also opened so that it operates only when the ON push button is pressed; now, the motor starts again.
Two protections have been used in this circuit: first short circuit, second overload. If for any reason, there is a short circuit in the motor or cable, the fuse in the power circuit will burn, and the motor will be turned off. Similarly, if the motor is overloaded, the contact of the overload relay gets opened as soon as the value is increased from the previously set current and the supply of coil A of the contactor is broken, due to which the contactor drops and the motor is turned off. And the motor is saved from burning on overload. The thermal overload relay is reset after it has cooled down to make the motor run again. By resetting, the contact of the relay comes back to its former position, that is, in the series of contactor coil A. Due to this, whenever the ON push button is pressed, the contactor coil A gets supply. Before resetting the thermal overload relay, it is important to check whether the motor overloading that caused the motor has been rectified.
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Now you must know DOL Starter Scheme and Wiring Diagram.