Motor Connections

Motor Connections

Connecting to 3 phase electric motors is various, namely:

• 1. Connection of DOL starter
• 2. Star Delta Connection

Before I discuss about star delta connections

first I will explain the relationship of the DOL starter

DOL starter or Direct On line is the connection of an electric motor directly with the source by combining 3 x-y-z terminals in series between one another

in general, this starter DOL only requires 1 contactor to help connect the source current to the 3 phase electric motor load

for the series of controls and their own power can be seen below.

Continue to the main topic, namely Connection or Star Delta connection

The star delta circuit is the most commonly used circuit for operating three-phase motors that have sufficient power. To move the motor indeed requires a large initial power, and with this type of circuit where the star circuit is used until everything becomes stable, the circuit is converted into a delta.

 This circuit has the function of reducing the number of start currents when the motor is first turned on. Because of this function, star delta is most widely used in the starting system in electric motors. The use of this circuit will reduce the surge of electric current when the motor is in the starter. The principle works is to make the initial star not be subjected to full voltage, that is by connecting with star. Then when the motor has rotated and the current has decreased, the timer function is running which will automatically replace the circuit into a delta. By changing into a delta, the current through the motor will be full.

this terminal connection is combined with the power circuit and controls as follows.

for this control circuit uses a timer to regulate how long the motor runs with a star or star system. With this timer it can be ascertained that this circuit works semi-automatically. so after the pb or push button is pressed, the current will turn on contactors 1 and 2 where contactor 2 is a star with a certain set time and then forward with a triangle or delta connection. why use 3 contactors?

actually this is for standardization and security of the motor so that it is more durable and not quickly damaged.

Can it star delta with 2 contactors?

of course you can because 1 contactor in star delta is useful for helpers and other contactors are star and delta contactors.