Answer / ranjit kumar mallick

In induction motor the rotor movement is due to it's
interaction with the stator resultant rotating magnetic
field flux and the resultant magnetic flux is due to the
three phase closed circuit. Once we ground the star point
the resultant magnetic field will drop and it becomes
extremely dangerous in case of fault as motor will run at
low speed without triping due to the current path available
to ground.So it will draw high current

Answer / sarwar

Star point of motor is not necessary to ground because a
motor is a balanced load.So,no current will flow through
star point to nutral.

Answer / vishwanath chothe

Grounding a motor star point will create an earth path for earth leakage current to flow through that motor's star point. If there are 10 motors in a process plant and their star points are all grounded, there are 10 additional paths for earth leakage currents to flow through.
If all the motors' star points are grounded in this way the earth fault current detections by the protection relays will be complicated and likely they will trip at the incorrect locations because earth fault currents are flowing in many directions toward multiple grounded neutral points.

Therefore the electrical consumers (ie the load, including the capacitor banks), even if they are star connected, are not to be grounded.

Answer / nadeem

Bcoz star point make additinal loop to source volatge and leads to burst the motor...

Answer / suresh

if unbalance current in motor then motoe burnt due to the
y point earthed

Answer / raju_

STAR CONNECTED WINDING IS CLOSE LOOP CIRCUIT IT SELF IF
YOU TRY TO GROUNDED THEN CRIRCUIT NOT GOING CLOSE THEN
MOTER WINDING IS NOT GENRETED E M F AND MOTER
CANT'PERFORMING WELL! THATS WHY WE CANT GROUNDED THE STAR
CONNECTED WINDING.

Answer / rsjendran

The star point of the motor can not be earthed since fault
currents from other systems may enter in to the motor
circuit ....

but normally motors are not protected againest this...

since it is advisable to ground the star point of the motor

thanks

Answer / sai

In the internal winding of the terminals shorted as a
nutral is Act to as earth.

why we testing the core balance of the transformer before comissioning?

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