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Thread: extruder lockout/estop

  1. #11
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    Quote Originally Posted by Besoeker3 View Post
    Why not on the input supply to the VFD? Wouldn't that be simpler/more effective?
    Usually simpler, if there is any need/desire to have the disconnect within sight of the motor/driven machine may not be so practical if the drive is in a remote location.
    I live for today, I'm just a day behind.

  2. #12
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    Quote Originally Posted by Besoeker3 View Post
    Why not on the input supply to the VFD? Wouldn't that be simpler/more effective?
    I usually figure on the drive being in a cabinet somewhere else and if you put the disconnect near the motor being serviced, you won't have to run your power leads back and forth. As Kwired mentioned, the aux contacts provide no safety benefit but if it saves a drive, or prevents opening or closing the disconnect under load, it's cheap insurance in my book.

  3. #13
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    Quote Originally Posted by cpickett View Post
    I usually figure on the drive being in a cabinet somewhere else and if you put the disconnect near the motor being serviced, you won't have to run your power leads back and forth. As Kwired mentioned, the aux contacts provide no safety benefit but if it saves a drive, or prevents opening or closing the disconnect under load, it's cheap insurance in my book.
    No running back and forth of power cables. The normal arrangement for the installations is a 3-phase supply to the drive and a 3-phase supply from the drive to the motor. The input to the drive got locked off, tagged off, padlocked. Usually there was a device so that multiple padlocks could be attached. The guy(s) working on the motor or driven plant would have their own keys.

    I carried my own set of padlocks. As did my guys.
    Just the way we did it.

  4. #14
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    Quote Originally Posted by Besoeker3 View Post
    No running back and forth of power cables. The normal arrangement for the installations is a 3-phase supply to the drive and a 3-phase supply from the drive to the motor. The input to the drive got locked off, tagged off, padlocked. Usually there was a device so that multiple padlocks could be attached. The guy(s) working on the motor or driven plant would have their own keys.

    I carried my own set of padlocks. As did my guys.
    Just the way we did it.
    lock with multiple padlocks for each worker is common thing and basically what OSHA would like to see as a general rule.

    The issue is NEC calls for a disconnect within sight of the motor, though when there is a VFD it potentially can trigger an exception to that rule, but the fact that one can put an aux contact in the disconnect to switch the VFD control circuit kind of eliminates any impracticality issue that triggers the exception.
    I live for today, I'm just a day behind.

  5. #15
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    Quote Originally Posted by kwired View Post
    lock with multiple padlocks for each worker is common thing and basically what OSHA would like to see as a general rule.

    The issue is NEC calls for a disconnect within sight of the motor, though when there is a VFD it potentially can trigger an exception to that rule, but the fact that one can put an aux contact in the disconnect to switch the VFD control circuit kind of eliminates any impracticality issue that triggers the exception.
    We have done that too, the line of sight disconnect. Just isolators not rated to make or break load current. But then you have auxiliaries like cooling fans, anti-condensation heaters. winding thermistors, and etc.

  6. #16
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    Quote Originally Posted by Besoeker3 View Post
    We have done that too, the line of sight disconnect. Just isolators not rated to make or break load current. But then you have auxiliaries like cooling fans, anti-condensation heaters. winding thermistors, and etc.
    Many those auxiliaries the NEC doesn't require disconnect to be within sight, but motors over 300VA or 1/8 HP it does.
    I live for today, I'm just a day behind.

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