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Thread: Replacement 3 phase On/Off Safety Switch

  1. #1
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    Replacement 3 phase On/Off Safety Switch

    We have a 10" 3 Hp 3 Phase Powermatic cabinet saw where I work. Currently the saw does not have the proper disconnect power protection nor does it have an off/on switch that has a large OFF button. We are looking for a Safety type on/off switch to put on this saw. Has anyone replaced their factory on off switch on a three phase saw?
    Lee Schierer
    USNA '71
    Go Navy!

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  2. #2
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    You will need to determine the kind of contactor the saw uses. The on/off switch is generally a remote control for the magnetic contactor for the saw. If it is in a commercial environment, it may require a licensed electrician to do it, and that person will know what you need.

  3. #3
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    Our electrician is the one that discovered the improper protection starter. He is not familiar with tables saw safety switches.
    Lee Schierer
    USNA '71
    Go Navy!

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  4. #4
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    A disconnect is easy enough to add between the saw and the power source. Your 3hp, 3-phase saw would need at least a 20A 3-pole knife switch. Some disconnects also include fuses on each leg, sized to protect the motor. Depending on code, disconnects are usually added when machinery is *hard-wired* to a circuit, with no plug and receptacle.

    Depending on how old, your PM should have a magnetic Furnas or Gould starter switch with overload heaters to protect the motor. The pushbuttons make or break current to the starter coil which starts/stops the motor. Of course, some other type of switch without overload protection could have been added, OR the heaters could have been replaced by only a jumper. A Pic would tell what kind of starter is installed on the saw.

    IF the starter is magnetic type, any momentary on/off pushbutton station (with big mushroom stop button) can be wired into it, and attached to the saw where most convenient.
    Last edited by Chip Lindley; 03-31-2010 at 4:14 AM.
    [/SIGPIC]Necessisity is the Mother of Invention, But If it Ain't Broke don't Fix It !!

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