Answer / prabhukumar

we all know that the starting current of motor is 5 times
more than of rated current.
for the starting current also some settings will be their
in that the starting current time may be less and the
starting time the heat will be their.

You just check it out and tell me.

prabhu.jsw@gmail.com

Answer / ghani

It is right that starting current of this much big motor is
very high whihc varies as per data from 6 to 8 times, so if
the protection relay is of static or digital then there
must be a restraining setting for starting current with
time delay, so you can increas both values keeping the data
sheet of motor in view.

Answer / kiran patil

You have increased thermal overload settings to .97 I think
because of load motor gets hot early and after incresing
the themal rating it will sustain.

Answer / a.kossay

FIRST OF ALL THIS MOTOR MUST HAVE A SOFT STARTER BECAUSE
STARTING THIS MOTOR WILL DRAW A HUGE AMOUNT OF INRUSH
CURRENT + HUGE AMOUNT OF STARTING CURRENT, SO YOU HAVE TO
USE SOFT STARTER , AND YOU HAVE TO USE SMART RELAY BECAUSE
STARTING AND INRUSH CURRENT CONATINS A HUGE AMOUNT OF
HARMONIC CONTENTS SPECIALLY THIRD HARMONIC SO THIS SMART
RELAY WILL DETECT THE VALUE OF THE THIRD HARMONIC COMPONENT
AND IF IT EXCEEDS ITS VALUE IT WILL TRIP

Answer / 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....

Answer / 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 .

how can i use REF and diffrencial relay both in 1 CT core for transformer protection?

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