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contactor
Last Post 20 Jul 2012 05:06 AM by cdw2152. 2 Replies.
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wanabeajedi
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Posts:2

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21 Jun 2012 11:23 AM
    PLS HELP im lost!!

    i have two motors controlling 2 extract fans from a panel housing the two contactors and relays sat next to the trend bms interface. contactors are 3phase with overloads and auxillary's with a 24v control, contactors fused via 3 seperate cartridge fuses

    fault occours on no.1 fan, found yellow phase fuse blown and contactor fused so changed both, tested overload no problem, tested motor, wiring relays and control voltage all fine!
    no. 1 contactor will not stay in on auto or hand, i reset via bms, the contactor comes in then 2 seconds later drops out on fault?????

    ive run out of ideas,
    wanabeajedi
    New Member
    New Member
    Posts:2

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    21 Jun 2012 11:45 AM
    to add to that, ive already increased the setting of the overload from 3amps to the max which is 4amps, the flow sensor on the extract fan is fine, there is no difference in voltage between phases or to earth, all connections are tight. the extract fans are in one unit so the damper will only allow 1 to run at a time and is opening and closing fine. mechanicaly the motor is fine because ive run them both off the no.2 contactor for some time and no problems, what could possibly be make the contactor come out??? the insulation resistance test on the wiring and the motor was as high as could be

    pls pls pls some1 help i want to understand this problem
    cdw2152
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    Posts:10

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    20 Jul 2012 05:06 AM
    You could have a short, pulling to many amps at start up, or the contactor is bad. I would put a clamp on meter on the motor leads and see how many amps your pulling at start up.
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