Star Delta Auto Transformer Starter Diagram

The starting current 6 to 8 times the rated current and this can cause voltage dip in supply and also motor and motor driven equipment experience large torque surge which can damage the motor as well as connected equipment.

Star delta auto transformer starter diagram. In contrast to the star delta connection only three motor leads and terminals are required. After the main contactor has been switched in the motor windings are applied to the full mains voltage finally the transformer is disconnected from the mains circuit. In this tutorial we will show the star delta y δ 3 phase induction ac motor starting method by automatic star delta starter with timer with schematic power control and wiring diagram as well as how star delta starter works and their applications with advantages and disadvantages. In the diagram of power circuit of star delta starter u2 and v2 of 3 phase motor should be connect to 4 and 6 respectively instead of u2 and v2 are connected to 6 and 4 of delta contector km2.

Star delta connection circuit diagram. Auto transformer starter diagram control circuit working autotransformer starter wiring diagram. The figure below shows the motor with the auto transformer starter. When a star delta starter changes the motor connections from star to delta a high transient current is generated that may cause false tripping of the other machines connected to the same line.

Auto transformer starter an auto transformer starter is suitable for both star and delta connected motors. There is minor correction is require to change printed in boxes sequence of 3 phase wires from w2 v2 u2 to w2 u2 v2 to get delta connection properly. Star delta starters consist of a power circuit and control circuit. The power circuit uses to create contact between the motor and three phase power supply.

Automatic star delta starter with timer for 3 phase ac motors. An auto transformer starter makes it possible to start squirrel cage induction motors with reduced starting current as the voltage across the motor is reduced during starting. The transformer s partial windings act as chokes in series to the motor windings and therefore like the uninterrupted star delta connection the motor speed does not drop during switch over. Auto transformer starter can be used for both star delta connected induction motors.