Motor protection
Motor protection
(OP)
When using a GE multilin 469 relay to protect a motor which has power factor capacitor installed where must the CT be installed.
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RE: Motor protection
If your protection CT is upstream of the capacitors, the measured current will be less than the actual current into the motor. You will need to compensate for this somehow, such as by adjusting the motor full load current that is entered into the relay. The relay's overload protection model depends on the measured current being equal to the current into the motor.
RE: Motor protection
RE: Motor protection
When the line power factor is corrected to 1.0 (maximum, but not the ideal), the total line current I2 reaches the minimum value:
I2 = I1*PF.
Were;
Il = Motor rms current without capacitors.
PF = Motor power factor.
RE: Motor protection
Accidentally dropped in a manual revision maybe? I purged myself of all my out-of-date manuals unfortunately (I told my wife that I would need them!). It would be interesting to see if that information was in there pre-GE.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: Motor protection
yours