Overcurrent Protection

Dear Experts

We have a SPM. Spindle motor is thro Star Delta contactor and overload relay with Main Contactor
Spindle stopped running as its bearing sieged very badly

Request to suggest better protective device having faster response to trip and avoid such seizure of bearings etc

Thanks and Regards

There should be a thermal overload relay between the contactor and the motor. The relay should be selected and adjusted for the nominal current of the motor.

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Quote:

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Originally Posted by M.RISHIKESH

Dear Experts

We have a SPM. Spindle motor is thro Star Delta contactor and overload relay with Main Contactor
Spindle stopped running as its bearing sieged very badly

Request to suggest better protective device having faster response to trip and avoid such seizure of bearings etc

Thanks and Regards

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A Bearing can seize at any time, a thermocouple can be added to the bearing housing and set for to trip the contactor once it reaches it's max operating temperature most large AC motors already have overtemperature protection with built in thermistors if wired in to the system they to would of protected the motor

If you are running a VFD Drive this is easy to setup to shut down if it see an over current, so as the bearing was getting hotter it would of been drawing a higher current and the VFD Drive would of shut down as an over current fault