Here we short the three terminals of one side (W2, U2, V2) and give our electrical supply to the remaining three points. As shown in the above image.

Difference between Star & Delta.

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Star Connected System.

• Star connection is used where we require Neutral terminal to obtain Phase voltage like above image.
• in a star connected system VL=√3Vph,mean Phase voltage is root 3 times less than line voltage.
• In a star Connected system IL=I phase.
• Star connected system require less insulation level.
• Star Connected system is used where low starting current is required.

Delta Connected System.

• In a Delta Connected system Line Voltage is equal to Phase Voltage.
• While phase current is √3 times less than Line current.
• Insulation level is high because line voltage = Phase Voltage.
• is generally used where high starting Torque is required.