Star-Delta Connection: Understanding Three-Phase Motor Starting

A Star-Delta starter is used with suitable three-phase induction motors to reduce the starting current by initially connecting the motor windings in Star and then changing to Delta (A) for normal operation.

The basic sequence is:

Start

Star connection

Transition Delta

connection

Normal running

A typical Star-Delta control system involves components such as:

Contactors

Timer

Overload relay

Start/Stop push buttons

Motor

Control and power circuits.