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 ?
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Answer Posted / parveen garg
I DO NOT KNOW ABOUT 6.6KV MOTORS & ALSO ABOUT K FACTOR.BUT
ACCORDING TO UR QUESTION IT LOOKS THAT MOTOR DRAW MORE
INSTANTANOUS CURRENT THAN ASSUMED BY THE CALCULATION & AT
THIS STARTING CURRENT OLR TRIPPED,WHEN U INCREASE THE
SETTING OF OLR.IT DO NOT TRIP.
FOR THE PROTECTION POINT OF VIEW ONE EXTRA CONTACTOR MAY BE
PROVIDE IN PARALLEL TO THE OPERATING CONACTOR WITH TIMER
WHICH WILL MADE OFF THE CONATCTOR(PROVIDED NEWLY)&ALSO THIS
CONTANCTOR WILL DRAW POWER FROM MAIN BUSBAR WITH EXTRA OLR .
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