Which type of starter is recommended for 100 hp, 440 V, 50 Hz, 3 phase Star connected squirrel cage induction motor for agriculture water pump application?

Which type of starter is recommended for 100 hp, 440 V, 50 Hz, 3 phase Star connected squirrel cage induction motor for agriculture water pump application? Correct Answer Auto transformer starter

Auto Transformer starter:

• An Autotransformer Starter is suitable for both star and delta connected motors.
• An Autotransformer starter is used to decrease the applied voltage to a motor throughout its beginning.
• In this method, the starting current is limited by using a three-phase autotransformer to reduce the initial stator applied voltage.

The figure below shows the motor with the autotransformer starter:

Additional Information

 Advantages of an Autotransformer starter:

• The inrush current can be restricted by using this transformer
• The starting voltage adjustment can be done through the choice of an appropriate tap on the transformer.
• The supply current is less as compared to the motor current
• The usage of excitation current is less
• While designing this transformer, less copper is required.
• Its efficiency is high as compared to the conventional one.
• Voltage regulation is much better.

Disadvantages of Autotransformer starter:

• Less power factor.
• The circuit is fairly complex & involves a comparatively expensive autotransformer.

Applications of Autotransformer:

• It is used to reduce voltage starter in induction motor
• Used as starting device for particular kinds of fluorescent light fixtures
• This transformer is used in induction & synchronous motors like a part for triggering purposes.
• Used to activate squirrel cage & slip-ring induction motors.