STAR DELTA STARTER
Star delta starter is a most common type of starter which used to start the three phase induction motor. In this method the motor winding are connected first in star connection for reducing starting phase voltage to achieving low starting current. When motor reaches at a certain speed than motor connected in delta connection. So this type of starting method is known as the Star Delta starter.
The power and control diagram of Star Delta starter is shown below.
1) Power diagram of Star Delta starter.
2) Control diagram of Star Delta starter
Components required in Star Delta starter
Some components are showing in below.
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1) PUSH BUTTON - Two push button are used in this starter. One is use to start the motor NO ( Normally Open) and second is use to stop the motor NC ( Normally Close).
2) MCB - Single pole and Three pole MCB are used in this starting method.
Singal pole MCB is use in control wiring and and Three pole MCB is use in power wiring.
3) OVER LOAD RELAY (OLR) - A thermal overload relay is used to protect the motor against different types of faults like as over voltage, under voltage, overload and single phase etc.
4) TIMER - In star delta starter ON delay timer used.
Advantages of Star Delta starter
1) Star Delta starter is the cheapest method to start a three phase induction motor.
2)Star Delta starter have a good torque and current performance.
3)The operation of star delta starter method is very simple.
4) The starting current is reducing to 33% of direct online starter.
5) Star Delta starter do not require any voltage reduction equipment.
Disadvantages of Star Delta starter.
1) Star Delta starter have low starting torque.
2)It required 2 set of cable from starter to motor.
3) It is unable to control the speed and unsuitable for aplication required speed control