We have 800KW motor operating at 6600Volt,50 Hz
supply.During 1st startup it tripped on overcurrent
trip.It's FLA is 88 Amps.The K factor of Thermal overloaaad
was set on .94 initially.then we set at 0.97 and then it
started fine.i dont understand why it tripped first?What
are the protections which comes in picture during starting ?

Answer Posted / karthik_elec

u did'nt mention which type of starter you used,and which type of operation no load or full load, this type large motors always used soft starter only, auto transformer will not use, any way at the time of starting auto transformer only gradually increase the applied voltage , at that time the motor will take more amps to obtain the specific torque, due to that only, after obtain normal amps it will not take 88 amps also, because this is 100% efficiency current, below that only....

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