What Is Star Connection And Delta Connection?

What is Star Connection and Delta Connection? | How is the star connection and delta connection done?

Discover the basics of Star and Delta connections with clear diagrams. Learn about Star Connection, its star point, properties, and total power formula. Explore Delta Connection, its diagram, and the differences between Star and Delta connections.

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The 3 Phase Winding connection is carefully configured to enhance the efficiency of the 3 Phase Supply System. This configuration is referred to as the internal connection of the 3 Phase system. The proper internal connection of the 3 Phase is of utmost importance for the effective transmission, distribution, and utilization of three-phase power.

Star Delta connection Diagram

Star Delta connection Diagram

This internal connection is made by Star & Delta  in these two ways.

Star Connection

This setup is known as a Star Connection or (Y) Connection. In the picture, you can see that there are two groups of terminals: U1, V1, W1, and U2, V2, W2. You connect all three terminals in one of these groups together, and the other three terminals are used for power supply.

Star Point Of Star Connection

 Properties of Star Connection

The Star Point of a Star Connection is where all the wires come together. We take the Neutral wire from this point.

Properties Of Star Connection

  • In Star Connection, phase current and line current are the same (IL = Iph) because of how it’s set up.
  • The line voltage is 3 times higher than the phase voltage (√3 times).
  • There’s a 60° phase difference between two of the wires, one with a negative phase voltage (-Vph) and the other with a positive phase voltage (Vph).
  • The line voltage is 30° higher than the phase voltage.
  • The total power in Star Connection equals the combined power of all three phases.


Formula for Total Power of Star Connection

Where Is Star Connection Used?

  • Star Connection is a way to connect wires in a 3-phase 4-wire system.
  • This system is used to distribute electricity.
  • It has 3 phase wires (R, Y, B) and a neutral wire (N) that connects to the star point.
  • Generating stations use star connection for alternators.
  • Star connection is useful for starting big 3-phase induction motors.

Delta Connection

Delta connection diagram

Delta Connection Diagram

How Is The Delta Connection Done?

A Delta connection is sometimes called a mesh connection.

In the picture above, you can see that in a Delta connection, certain points in a 3 Phase Winding are connected together. Then, three wires are connected to these joined points for electricity to flow through. These wires are labeled U, V, and W in a 3 phase winding, and they connect in a way like this: U1 to V2, V1 to W2, and W1 to U2. This setup is what makes the Delta connection.

Properties Of Delta Connection

  • In this connection, each phase winding has parallel phases of 2 phase, due to which the phase voltage and line voltage are the same.
  • The line current is √3 times higher than the phase current.

What Is The Difference Between A Star And A Delta Connection?

Star ConnectionDelta Connection
Line current is the same as phase current.Line current is √3 times the phase current.
Line voltage is √3 times the phase voltage.Line Voltage equals Phase Voltage.
Total power = √3 times VL × IL × power factor.Total power = √3 times VL × IL × power factor.
High number of turns due to the same line and phase voltage, saving copper.Lower number of turns.
Neutral is available.No neutral.
240V phase voltage and 415V line voltage available, suitable for combined lighting and power loads.Only 415V 3-phase available, not suitable for single-phase loads.
Line current leads phase current by 30°.Line current lags phase current by 30°.
Lower breakdown voltage.Low breakdown voltage.
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