Autotransformer starter ppt

YPeS of Starter for 3-Ph InductIon motorS For slip-ring induction motors: Rotor rheostat starter For squirrel cage induction motors: D. StartIng of SlIP rIng InductIon motor In . When the motor speed reaches the desired level, autotransformer is disconnected and motor is connected directly across the supply. The stator of the motor is connected . In contrast to the star-delta connection, only three motor leads and terminals are required.

Major disadvantage is the high in-rush current.

Large voltage drops occur, dimming lights and forcing computers off-line.

Autotransformer Starter Starting Method. 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. Benefits Soft start and soft stop Reduced . As the starting torque is low, it should be raised by increasing the offset between the two fields the coils produce.

Keywords: Direct-on-Line (DOL) starter, Star-delta starter, auto- transformer starter , rotor resistance starter, starting current, starting torque, starters for squirrel cage and wound rotor induction motor, need for starters. Line current and starting torque vary with the square of the voltage applied to the motor, so the percent tap will deliver only percent of the full- voltage . Motors AC-Motors Parts of an Electric Motor A. Rotor : Revolving Part The rotary motion in an ac-motor is caused by the fundamental law of magnetism.

This law states that like poles repel and unlike poles attract. Across the Line Starting of Induction Motors. Auto-transformers are also known as auto- starters.

They can be used for both star connected or delta connected squirrel cage motors.

With auto-transformer starting, . An auto-transformer starter makes it possible to start squirrel-cage induction motors with reduced starting current, as the voltage across the. DOL(Direct on Line) RDOL (Reverse Direct on Line) Start Delta starter Soft starter (Drive) Auto transformer To provide starting but to reduce heavy starting currents . DISADVANTAGE OF DOL Starting current of an induction motor can be 6-times the running current. DOL starter is typically only used for motors with a . Also, a Wye-Delta start is similar in its effect on torque as would be seen on . DC and AC motor starter Necessity of starter Function of starter Dc motor starter Ac motor starter.

Applications of Auto transformer. The low-voltage control compartment is isolated from medium voltage by grounded steel barriers. This type of starter circuit uses an autotransformer to apply reduced voltage across the windings of the motor during startup.

Squirrel cage, primary reactor. Three autotransformers are connected in the star configuration and taps are selecte to provide an adequate starting . Indian Institute of Technology Madras.