Star Connection in Motor

The star connection, also known as the Y-connection, is a common wiring configuration used in three-phase electric motors.

In a star connection, the three windings of the motor are connected at a common point, often referred to as the neutral point. The other ends of the windings are connected to the three phases of the power supply.

One of the main advantages of the star connection is that it reduces the voltage across each winding. The voltage across each winding is approximately 57.7% (or 1/√3 times) of the line voltage. This lower voltage per winding can be beneficial in certain situations, such as when the motor insulation is not rated for high voltages.

It also provides a balanced phase current and reduces the starting current compared to a delta connection. This makes it suitable for applications where a reduced starting current is desired to avoid excessive voltage drops in the power supply system.

For example, in large industrial motors where starting current needs to be controlled to minimize disturbances in the power grid, a star connection might be used during the starting phase and then switched to a delta connection for normal operation.

In summary, the star connection in motors offers specific electrical characteristics that make it a valuable option in many three-phase motor applications, depending on the requirements of the system.