Autotransformer starter theory

An Auto transformer Starter is suitable for both star and delta connected motors. An auto-transformer starter makes it possible to start squirrel-cage induction motors with reduced starting current, as the voltage across the. This motor starting method has been updated and improved by Hilton Raymond Bacon . In the autotransformer , part of the energy is transferred by induction and the rest is by conduction. There are three types of auto transformers: step-up, step-down, and variable auto transformers which can be either step-up or .

In Auto Transformer , one single winding is used as primary winding as well as secondary winding.

But in two windings transformer two different windings are used for primary and secondary purpose.

A diagram of auto transformer is shown below. The winding AB of total turns Nis considered as . To start the induction motor using 3-phase auto-transformer. This starter produces high efficiency and have the option to be adjusted to obtain the necessary torque and in accordance with the system. It very efficiency stater but the disadvantage is it very high cost to setup control panel stater.

It can improved torque ratio is achieved and starting current is typically 3 . To limit this high starting current of Induction Motor, different starting methods are used.

Applications, Features, Description. An autotransformer is an electrical transformer with only one winding. The auto ( Greek for self) prefix refers to the single coil acting alone and not to any kind of automatic mechanism.

In an autotransformer , portions of the same winding act as both the primary and secondary sides of . This is another starting method that reduces the starting current and starting torque but contrary to Star-Delta starting where this starting method needs three wires and three terminals on the motor.

Auto-transformers are also known as auto- starters. Autotransformer Starter Starting Method. They can be used for both star connected or delta connected squirrel cage motors.

With auto-transformer starting, . Two methods used for reduction of starting voltage are: Star-delta starting and auto transformer starting.

In open transition the power is. Two methods are used for reduction of starting voltage are star delta starting and auto transformer stating. The currents through the winding are . ATL - Across The Line Starters.