A star delta starter is the most commonly used method for the starting of a 3 phase induction motor. In star delta starting an induction motor is connected in through a star connection throughout the starting period. Then once the motor reaches the required speed, the motor is connected in through a delta connection.
A star delta starter will start a motor with a star connected stator winding. When motor reaches about 80% of its full load speed, it will begin to run in a delta connected stator winding.
Star Delta Starter Relay Range , Contactor size and many more things are given in the chart
The contactor consists of a fixed contact system with a magnetic core and solenoid coil, a moving contact system with armature. These Air Break Contactors are of bounce free double break design with sllver contact tips. Springs used are of stainless steel and contacts are tested for millions of operations.
The triple pole bimetallic thermal overload relay is of the hand reset type, it unmistakably indicates overload. A temperature compensation device prevents the relay from being affected by variation in ambient temperature, housed in a bakelite enclosure. The entire relay unit is accurately calibrated and individually tested on an automatic test bench. Setting can be adjusted by means of a pointer. Relays are availble in different ranges to suit motors up to 25HP.
Under voltage protection is provided by the coil of the contactor. machine wound. vacuum impregneted and baked. PE-1 coils are tested for inter- turnshort citcuit. they undergo a 4000 v impulse test.
Shrouded start and stop push buttons are mounted on the front cover. The stop button which can be latched in the pressed position from outside also acts as the reset button for hand reset of the OVERLOAD RELAYS.
TO DOWNLOAD THE STARDELATA SELECTION CHART CLICK ON THE LINK - star delta starter.docx