excessive voltage drop across contactor
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  1. #1
    Join Date
    Jan 2004
    Location
    Midlothian, Virginia
    Posts
    195


    What voltage drop across a contactor is considered excessive and the contactor is declared no good.
    Goodbyee stranger it's been nice. Hope you find your paradise! Hey it aint rocket science, "It's a Trade !"

  2. #2
    Join Date
    Nov 2004
    Location
    CA
    Posts
    238
    The contactor should not have a big V drop, so you should be able to measure 25-26V when the unit is working.

  3. #3
    Join Date
    Nov 2002
    Location
    omaha/ne
    Posts
    66
    I usually recommend replacement if it reads .04v or higher

  4. #4
    Join Date
    Sep 2004
    Location
    Glendale AZ
    Posts
    299
    Are you talking hi or low voltage? No drop on hi -- you usually need at least 24 v to energize the coil so what drop are you talking about?

    [Edited by danj on 04-05-2005 at 09:59 PM]
    The bitterness of poor quality remains long after the sweetness of low price has gone.

  5. #5
    anything over half of a volt drop across the contact is too high

  6. #6
    Join Date
    Jan 2004
    Location
    Midlothian, Virginia
    Posts
    195
    im talking about the high voltage drop across the contactor.

    put your meter on voltage setting. place leads across open contactor and you usually see about 240 volts. energize the coil the contacts pull in, let system run awhile and now you read voltage across closed contactor. through the contacts that are now closed. i wish you could draw on here.

    this is the voltage drop im talking about. my meter usually reads about .02 volts on a tipically good contactor. ok over years contacts burn because arcs form upon closing and resistance builds after repeated closing and burning. this resistance causes a small but growing voltage drop as the contacts age.

    the company i work for has two electricians they feel the voltage drop is bad at .2 volts. i have heard another tech say .4 volts. i just would like to hear what most of you old pros think.
    Goodbyee stranger it's been nice. Hope you find your paradise! Hey it aint rocket science, "It's a Trade !"

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