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  1. #1
    Registered
    Join Date
    Dec 2006
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    305

    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

  2. #2
    Registered
    Join Date
    Nov 2012
    Posts
    1013

    Re: Overcurrent Protection

    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.






  3. #3
    Member
    Join Date
    Jan 2005
    Posts
    11899

    Re: Overcurrent Protection

    Quote Originally Posted by M.RISHIKESH View Post
    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
    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
    Mactec54

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