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What is Star-Delta Starter?

Star-Delta Starter is the most commonly used method that reduces the starting current and starting torque of an electrical motor.  The star/delta are used in an attempt to reduce the start current applied to the motor for reducing the trouble and intervention on the electrical supply.  Star/delta are consist of three contactors- An overload relay or circuit breaker and a timer. For the functioning of the delta starter, a motor must be connected to the delta.  In the star-delta starter, starting current is 33% during direct online start, and starting torque is reduced by about 33% of the torque available at a direct online starter. 

Types of Star-Delta Starter -

There are 3 types of star-delta starter:

1. Manual Star-Delta Starter - 

Manual star delta is a perfect solution for Oil mills, Flour mills and Agro Industries. It gives assurance of same dependability and protection.

2. Semi-Automatic Star-Delta Starter -

These starters work with a 3-push button system. The third push yellow button is used to change the sequence of the running motor from Star to Delta. To protect against overloading and single phasing problem bimetallic thermal overload Relay is fitted in these starters.

3. Fully Automatic Star Delta Starter (wye delta) -

These starters work automatically with the help of the timer fitted inside the starter. The time period can be adjusted between 7 to 15 sec.

Star-Delta Starter working principle: 

1. When Star/Delta motor starts working, the start-up of the three-phase induction motor is applied by a changeover of windings.  2. All 6 winding connections are attached to the main supply with the help of Star-Delta Switch and, jumpers in the motor terminal box are excluded.  3. The windings of the motor are connected throughout the operating connection.  4. The winding voltage (WV) must be equal to the phase voltage of the three-phase system. 5. In a star connection, the mains voltage (ULN) on the individual motor windings is lower by a factor of 0.58.

Advantages of Star-Delta Starter: 

Star Delta-Starter are widely used because of their low price. 

There is no limit on operating them. 

The components of star/delta do not require much space. 

It reduces mechanical stress on the motors. 

The operating function of star/delta is simple.

Disadvantages of Star-Delta Starter: 

The star/delta can only be applied to motors where the six leads and terminals can be accessed. 

Once the starting torque is reduced to 33% it cannot be adjusted. 

There are many devices and much wiring. 

It requires higher maintenance. 

When the starting current is reduced to approximately one-third of the rated current, the starting torque is also reduced to one-third.

To know more, visit : https://www.gotosage.in/