Star Point

In order for three phase currents to result in zero at the star connection, they must be 120 degrees out of phase and equal magnitudes. Why would you think Kirchhoff's Law would not work? read all of this.

Note that Star point will be zero only at balanced load. Also you can use the Kirchoff's current law to any node of current analyse. Here also you can use the Kirchoff's Current Law...

Abdullah.

Kirchoff's law can be applied anywhere that there are not electrons spewing out the ends or sides of conductors.

Quote Abdullah "Note that Star point will be zero only at balanced load."

The loads must have the same power factor. You could have all 3 phases reading 100 amps but have different phase angles and would not sum to zero at the star node.

I said Balance Load. I does consider the phase angle too....

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I think that some of this stuff you must just think it over...may be you ment that your voltage in the star point is zero...your current are summulating through your star point at 50cps

AP#1 I believe if you add Ia /0 deg + Ib /120 deg + Ic /ang 240 deg you will get zero. You can add them using vectors very easily. If you assume the magnitude of I = 1 then

Ia = 1 + j0

Ib = -0.5 + J 0.886

Ic = -0.5 - j 0.866

total = 0

you already mentioned kirchof's current law...the basic principle is taking a node (a point perhaps) where you start your assumptions of your calculations...note that in kirchof's method you emphasize the direction in which current flows...now, consider a star connection....each phase consist a phase current having a magnitude and direction (say 120 elect. degrees), now this quantity becomes a vector quantity...and finally, consider the star point as your "node", apply kirchof's law and consider the directions..sum it up...then your answer will still be zero....

..ps...assume a balanced system....

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