Star (Y) Connection
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In star connection,the starting or finishing ends (Similar ends) of three coils are connected together to form the neutral point. A common wire is taken out from the neutral point which is called neutral.
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There is a neutral or star point
3.Three phase four wire system is derived from star connection
4.Line current equal to phase current
5.Line voltage is √3 times of phase voltage
6.The speed of star connected motors are slow as they receive 1/√3 voltage
7.In star connection the phase voltage is low as 1/√3 of the line voltage so it needs low number of turns hence saving in copper
8.Low insulation required as phase voltage is low
9.In power transmission star connection system is general and typical to be used.
Delta ( Δ) Connection
1.In delta connection,the opposite ends of three coils are connected together.In other words,the end of each coil is connected with the start of another coil and three wires are taken out from the coil joints.
2.No neutral points in delta connection
3.Three phase three wire system derived from star connection
4.Line voltage is equal to phase voltage
5.Line current is √3 times of phase current
6.The speed of delta connected motors are high because each phase gets the total of line voltage
7.In delta connection the phase voltage is to the line voltage hence it needs more number of turns
8.Heavy insulation required as phase voltage = line voltage
9.In power distribution and industries delta connection is general and typical to be used