rseee Posted June 5, 2008 Report Share Posted June 5, 2008 what are the causes of Unbalanced load in 3 phase circuits? How large unbalanced load causes burning of motor? Link to comment Share on other sites More sharing options...
subrao Posted July 17, 2008 Report Share Posted July 17, 2008 There are basically two sources of unbalanced currents in a 3-phase system driving motor loads 1 From source voltage source voltage is not perfectly balanced.Either magnitudes of the phase voltages are not exactly equal or the phase angle between them is not exactly 120 degrees 2.From load side There is unbalance in connected load 3. Defective motor No .of turns on all phase windings are not exactly same. windings are not distributed equally in space may be due to problem in number of slots that is number of slots not divisible by phase-pole belts. Generally speaking a standard motor can take an unbalance voltage of 1%. Beyond this it has to be de-rated and used up to 5% unbalance. Above 5% unbalance it should not be operated Link to comment Share on other sites More sharing options...
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