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What is the function of the shorting contactor for an ATS48? Is it a required component?

Published date: 20 May 2020

Is the shorting contactor for an ATS48 a required component?

Product Line:
Altistart 48




A shorting contactor engages when the motor is running at full speed.  The starter provides proper sequencing of this contactor by the ``end of starting`` relay (R2).  When the start is completed, the shorting contactor will be commanded to close.  The starter will continue to monitor the motor thermal state and provide motor overload protection.  Upon a stop command, the KM3 (shorting contactor designation) contactor will open, transferring the motor current to the SCRs to allow for a controlled deceleration if desired.

The shorting contactor is not required, but there are definite advantages to using one:
  • It extends the life of the internal electronics and SCRs due to the reduced heat effects of the current and SCR firing.
  • It reduces the heat dissipated by the controller.


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