# Power Engineering Unbalanced 3 Phase

Discussion in 'Homework Help' started by cable, Aug 25, 2007.

1. ### cable Thread Starter New Member

Aug 25, 2007
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Three 230volt single phase resistive loads 20ohm 40ohm and 60ohm are powered from a 400volt Y 4 wire supply. What would be the phase voltages on the three loads if the supply neutral to ground connection was interrupted. What would be the neutral voltage.

2. ### recca02 Senior Member

Apr 2, 2007
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i would attempt it in this way. (but m not sure if that is the proper way to go)
or u can always take time and learn symmetrical components.

consider line values i;e r-y,y-b,b-r in order with 120 deg angle between them in increasing order.
now solve with V = IR for each line combination i;e r-y,y-b,b-r in order.
now take vector sum of all voltages at neutral point arrived with three combn.
i think that shud do it.

edit :congrats mr hgmjr on 2000    Jan 28, 2005
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4. ### Newton1Law Member

Aug 22, 2007
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Create two current loops. Solve the loop equations to get Vr20= 30.6 angle -67.58, Vr60= 378.96 angle 81.5, Vr40 = 193.80 angle -85.86. This assumes 20 ohms resistor supplied by 230 volts angle 0, 60 ohms resistor by 230 volts angle 120, and the 40 ohm resistor is supplied by 230 volts abgle 240.

Neutral voltage will be 173.63 angle 61.94.