11-differences between star connection and delta connections


11-differences between start connection and delta connections

Sl No.

Star connection

Delta connection


Two types of star connections are possible

A-4-wire, 3-phase system

B-3 wire. 3-phase system

Only 3 wire. 3-phase system is possible


Out of 4 wires, 3 wires are the phases and one is neutral

All 3 wires are phases in Delta connection


In Star  connection, one end of all the three wires are connected to a common point in the shape of Y to form neutral

In Delta connection every wire is connected to two adjacent wires in the form of triangle.And all the three common points of the connection form the three phases


Line current and phase currents are same

Line current and phase current are different.Line current =Phase current


Line voltage and phase voltages are different, Line voltage =Phase voltage

Line voltage and phase voltages are same


Since line voltage is more than phase voltage, insulation required for each phase is less

In Delta connection line and phase voltages are same hence more insulation is required


Star connections are used for both transmission and distribution applications/networks

This connection is generally used for distribution networks


Since insulation required is less, these connections are used for longer distances

Since insulation required is more, these connections are used for shorter distances


Star  connections are used where less starting current and starting torque is required

Delta connections are used where starting current and Torque is more


Power calculation in Start connections.


P = 3 X Vp X Ip X Cosθ




P = (√3 X VL) X IL X Cosθ

Power calculation in Delta connections.


P = 3 X Vp X Ip X Cosθ




P = (√3 X IL) X VL X Cosθ




In star connections different voltage levels are used as line voltage & phase voltages are different

In Delta connections, only single voltage is used

For more articles on power plant and calculations read >>>>power plant and calculations

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