Differences between star, delta connection

 Star (Y) and Delta (Δ) connections are methods of connecting the windings of a three-phase system in electrical engineering. Here are the key differences between them:

 Star Connection (Y)

1. Configuration:

 - Each of the three phases is connected to a common point called the neutral point.

 - The other end of each phase winding is connected to the line terminals.

2. Voltage:

 - Line voltage (voltage between any two lines) is √3 times the phase voltage (voltage between any line and the neutral point).

 - Line voltage = √3 × Phase voltage.

3. Current:

 - Line current is equal to the phase current.

4. Application:

 - Commonly used in applications requiring a neutral for returning currents, such as distribution systems.

 - Suitable for long-distance power transmission because it can operate with lower current and thus has reduced line losses.

5. Starting Method:

 - Often used in the starting method for motors where a star-delta starter is employed to reduce the initial current surge.

 Delta Connection (Δ)

1. Configuration:

 - The end of each phase winding is connected to the start of the next, forming a closed loop or triangle.

 - No neutral point is present.

2. Voltage:

 - Line voltage is equal to the phase voltage.

 - Line voltage = Phase voltage.

3. Current:

 - Line current (current through each line) is √3 times the phase current.

 - Line current = √3 × Phase current.

4. Application:

 - Commonly used in applications where a neutral is not required, such as in motor windings.

 - Suitable for systems requiring high starting torque, such as industrial motors.

5. Starting Method:

 - Used for the running configuration of motors when high torque is needed.

Summary

-Voltage Relation: 

In star connection, line voltage is √3 times the phase voltage. In delta connection, line voltage is equal to the phase voltage.

-Current Relation:

 In star connection, line current is equal to the phase current. In delta connection, line current is √3 times the phase current.

Neutral Availability: 

Star connection provides a neutral point; delta connection does not.

Applications: 

Star is used for long-distance transmission and distribution systems, delta is used for high-torque motor applications.

Choosing between star and delta configurations depends on the specific requirements of the electrical system, such as the need for a neutral point, voltage and current specifications, and the type of load being powered.