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Thread: Phase rotation

  1. #11
    Join Date
    Aug 2017
    Location
    Maui
    Posts
    16
    Am I correct in saying you can switch any two phases to reverse the rotation?
    Also, do you guys qualify bumping the motor in the presence of a mechanical contractor and potentially having him sign off or is that a bit overkill?

  2. #12
    Join Date
    Dec 2010
    Location
    Tennessee NEC:2008
    Posts
    4,840
    Quote Originally Posted by follybeacher View Post
    Am I correct in saying you can switch any two phases to reverse the rotation?
    Also, do you guys qualify bumping the motor in the presence of a mechanical contractor and potentially having him sign off or is that a bit overkill?
    Yes, swapping any two conductors will reverse the rotation.
    I don't always have a witness when checking rotation but I don't think it is overkill.
    If you aim at nothing, you will hit it every time!

  3. #13
    Join Date
    Jan 2018
    Location
    SE Michigan
    Posts
    113
    This is the model I prefer, rugged and no batteries to go bad in the housing.
    Instructions PDF on the page.
    http://www.tesco-advent.com/knopp-ph...indicator.html


    Click image for larger version. 

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    Along with the favorite solenoid tester. Compact and rugged.
    http://www.tesco-advent.com/knopp-voltage-tester.html

    Click image for larger version. 

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  4. #14
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
    Posts
    19,639
    Quote Originally Posted by MTW View Post
    This is the model I prefer, rugged and no batteries to go bad in the housing.
    Instructions PDF on the page.
    http://www.tesco-advent.com/knopp-ph...indicator.html
    IMHO it is hard to find a more concrete and positive correlation to lead phase rotation as it affects motor rotation than a motor!
    I love it. Also a very unambiguous detection of phase loss via the failure of the motor to rotate. (It does not, however, tell you the details of the phase loss in terms of duplicated, open circuited, shorted, etc.)

  5. #15
    Join Date
    Sep 2008
    Location
    UK
    Posts
    12,025
    Quote Originally Posted by charlie k. View Post
    Read the directions. That is the easiest way. You will need a phase rotation meter and they come with the directions.
    Wouldn't you just try the rotation before coupling it to the load? I mean, even if you use a meter to test the phase rotation would you necessarily know how the rotor was previously connected? L1, L2, L3, or L2, L1, L3?
    Si hoc legere scis nimium eruditionis habes.

  6. #16
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    38,252
    For existing installations where you are doing work anywhere in the supply chain, you don't even need a rotation meter, but you must mark all lines that will have any work done to them in a manner that you can assure will get put back the same rotation as they originally were.

    Have a disconnect gone bad and needs replaced, mark incoming lines and outgoing lines whether it be phase tape or simply putting I,II,III ink marks on the conductors before disassembling works great. If original install already has a phase ID method going on then it is even simpler, put things back the way they were to begin with.
    I live for today, I'm just a day behind.

  7. #17
    Join Date
    Jun 2003
    Location
    NE (9.1 miles @5.07 Degrees from Winged Horses)
    Posts
    10,067
    I remember no phase markings, unless there was a Hi leg or grounded leg and no knowledge of SE rotation, let alone at a controller.
    Tom
    TBLO

  8. #18
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    38,252
    Quote Originally Posted by ptonsparky View Post
    Maybe in the perfect world ABC rotation at the SE means ABC throughout the plant all the way to the motors, but don’t count on it.
    Never seen a reversing controller that will also change conductor markings when it reverses, need to develop that idea and patent it
    I live for today, I'm just a day behind.

  9. #19
    Join Date
    Mar 2003
    Location
    New York
    Posts
    1,331
    You can buy a rotation meter that will test live and test the motor dead, now you know the motor winding rotation and the old gear rotation.

  10. #20
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    38,252
    If you are changing something in a service or a feeder that supplies many motors and not touching any branch circuits, and forget to pay attention to phasing before you started work, all you need to do is check the easiest to get to motor for proper rotation when you get things on again. If it is correct they all will be correct. Equipment with a phase monitor installed on it won't run if you end up getting phasing reversed. This leaves you with making sure high leg is in correct position if you happen to have one, but that often is more critical than correct rotation and should be checked before energizing any loads.
    I live for today, I'm just a day behind.

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