14 Difference Between Star And Delta Connection

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What Is Star Connection?

In star connection, one end of all the three wires are connected to a common point in the shape of Y, such that all the three ends of the three wires form the three phases and the common point forms the neutral.  Star connection is preferred for long distance power transmission because it is having the neutral point.

In star connection, the line voltage is √3 times of phase voltage. Line voltage is the voltage between two phases in three phase circuit and phase voltage is the voltage between one phase to the neutral line. And the current is same for both line and phase.

Star Connection

What You Need To Know About Star Connection

  1. In star connection, one end of all the three wires are connected to a common point in the shape of Y, such that all the three ends of the three wires form the three phases and the common point forms the neutral.
  2. In star connection, 3 out of the 4 wires are phases whereas 1 is the neutral.
  3. In star connection, there is a neutral point and it can be earthed.
  4. The line current is equal to the phase current in star connection.
  5. The amount of insulation required in star connection is low.
  6. Star configuration is primarily used in power transmission.
  7. In star connection, the phase voltage is low as 1∕√3 of the line voltage therefore it needs low number of turns hence saving in copper.
  8. In star connection each winding receives 230 volts.
  9. Both 3 phase 4 wire and 3 phase 3 wire system can be derived in the star connection.
  10. The speed of star connected motors is slow as they receive 1/√3 of the voltage.
  11. Star connections are mainly required for the Power Transmission Network for longer distance.
  12. Star connections are often used in applications which require less starting current.
  13. In star connection, smooth starting and operation with nominal power, normal operation without overheating can be achieved.
  14. Total power of three phases in a star connection can be calculated using the following formulae: P=3 X VP X IP X Cos(Ɵ) or P= √3 X VL X IL X Cos (Ɵ).

Also Read: Difference Between Single-Phase And Three-Phase Power Supply

Delta Connection

In delta connection, every wire is connected to two adjacent wires in the form of a triangle and all the three common points of the connection form the three phases. Normally, delta connection is preferred for short distance due to the problem of unbalanced current in the circuit. In delta connection, the line voltage is the same as that of phase voltage. And the line current is √3 times of phase current. 

In a three-phase circuit, star and delta connection can be arranged in four ways:

  • Star-star connection
  • Star-delta connection
  • Delta-star connection
  • Delta-delta connection
Delta Connection

What You Need To Know About Delta Connection

  1. In delta connection, every wire is connected to two adjacent wires in the form of a triangle and all the three common points of the connection form the three phases.
  2. In delta connection, all the three wires are phases.
  3. There is no neutral point in delta connection.
  4. The line current is equal to the root three times of the phase current.
  5. The amount of insulation required in delta connection is high.
  6. Delta configuration is generally used in power distribution and various industrial setups.
  7. In delta connection, the phase voltage is equal to the line voltage hence it requires more number of turns.
  8. In delta connection, each winding receives 415 volts.
  9. In delta connection only 3 phase 4 wire system can be derived.
  10. The speed of delta connected motors is high because each phase gets the total of the line voltage.
  11. In delta connection mainly in distribution networks and is used for shorter distances.
  12. Delta connections are often used in applications which require high starting torque.
  13. In delta connection, motor receives highest power output.
  14. Total power of three phases in a delta connection can be calculated using the following formulae: P= 3 X VP X IP X Cos (Ɵ) or P= √3 X VL X IL X Cos (Ɵ).

Also Read: Difference Between Single-Phase And Three-Phase Power Supply

Difference Between Star And Delta Connection In Tabular Form

BASIS OF COMPARISON STAR CONNECTION DELTA CONNECTION
Description In star connection, one end of all the three wires are connected to a common point in the shape of Y, such that all the three ends of the three wires form the three phases and the common point forms the neutral.   In delta connection, every wire is connected to two adjacent wires in the form of a triangle and all the three common points of the connection form the three phases.  
Wires In star connection, 3 out of the 4 wires are phases whereas 1 is the neutral.   In delta connection, all the three wires are phases.  
Neutral Point In star connection, there is a neutral point and it can be earthed.   There is no neutral point in delta connection.  
Line Current The line current is equal to the phase current in star connection.   The line current is equal to the root three times of the phase current.  
 Insulation The amount of insulation required in star connection is low.   The amount of insulation required in delta connection is high.  
Use Star configuration is primarily used in power transmission.   Delta configuration is generally used in power distribution and various industrial setups.  
Phase Voltage In star connection, the phase voltage is low as 1∕√3 of the line voltage therefore it needs low number of turns hence saving in copper.   In delta connection, the phase voltage is equal to the line voltage hence it requires more number of turns.  
Winding In star connection each winding receives 230 volts.   In delta connection, each winding receives 415 volts.  
Phase Wire System Both 3 phase 4 wire and 3 phase 3 wire system can be derived in the star connection.   In delta connection only 3 phase 4 wire system can be derived.  
Speed Of Motors The speed of star connected motors is slow as they receive 1/√3 of the voltage.     The speed of delta connected motors is high because each phase gets the total of the line voltage.  
Application Star connections are mainly required for the Power Transmission Network for longer distance.   Delta connection is mainly used in distribution networks and is used for shorter distances.  
Use Star connections are often used in applications which require less starting current.   Delta connections are often used in applications which require high starting torque.  
Power In star connection, smooth starting and operation with nominal power, normal operation without overheating can be achieved.   In delta connection, motor receives highest power output.  
Formulae Total power of three phases in a star connection can be calculated using the following formulae: P=3 X VP X IP X Cos(Ɵ) or P= √3 X VL X IL X Cos (Ɵ).   Total power of three phases in a delta connection can be calculated using the following formulae: P= 3 X VP X IP X Cos (Ɵ) or P= √3 X VL X IL X Cos (Ɵ).  

Also Read: Difference Between Relay And Contactor