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Thread: exhaust fans

  1. #1
    Join Date
    Oct 2008
    Location
    florida
    Posts
    138

    exhaust fans

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    Is there a replacement component that can be used in place of motor starters for 3 phase exhaust hood motors? That auto reset automatically?i had 3 fans go out this weekend for a customer that needed to be manually reset.All amp draws were normal and within limits after resets were pushed.Something like a phase monitor?

  2. #2
    Join Date
    Jun 2004
    Location
    St Paul, minnesota
    Posts
    1,233
    they make auto reset starters

  3. #3
    Join Date
    Sep 2008
    Location
    Cedar Rapids, IA
    Posts
    486
    You can put the auto reset overload modules on existing starters. If you are trying to protect multiple fans from an external single phase event then a good solution would be a 3 phase monitor. ICM makes one that will auto reset and is adjustable for phase loss, voltage low, high, unbalanced, etc.

  4. #4
    Putting auto-reset O/L relays on unattended equipment is a bad idea. There is a reason that they trip & blindly resetting protective equipment then walking away W/O finding the cause is not a good idea.

  5. #5
    Join Date
    Oct 2008
    Location
    florida
    Posts
    138
    great point to consider.

  6. #6
    Join Date
    Feb 2007
    Location
    Northern Ontario
    Posts
    128
    If you install self resetting limits we replace lots of motors they are there for a reason....

  7. #7
    Join Date
    Oct 2007
    Location
    Plainfield Il
    Posts
    43
    If all three hoods went down at the same time sound like a power surge or a dropped leg to the units. I had a store that had auto resets and the store lost a leg, the 3 phase motors were single phasing for hours on and off until the burnt them selfs up. Not a good idea the have the automatic resets

  8. #8
    Join Date
    Aug 2008
    Posts
    322

    Commercial food service equipment

    Iam having the same problem with the hood fan over our grill in the kitchen in food service Ihave checked amp draw way below the motor ratings as well on the heaters in the motor starter put on avoltage monitor for about aweek hood never failed , Just wondering we had to leave the door open to leave monitor hooked up maybe heat build up in enclosure?

  9. #9
    Join Date
    Oct 2007
    Location
    Plainfield Il
    Posts
    43
    Quote Originally Posted by mike robinson View Post
    Iam having the same problem with the hood fan over our grill in the kitchen in food service Ihave checked amp draw way below the motor ratings as well on the heaters in the motor starter put on avoltage monitor for about aweek hood never failed , Just wondering we had to leave the door open to leave monitor hooked up maybe heat build up in enclosure?
    Please explain a little more on the problem you are having. You say the amp draw is way below the spec. WHats the spec and the actual amp draw???? Under loading the motor is almost as bad as overloading them.

  10. #10
    Join Date
    Sep 2008
    Location
    Cedar Rapids, IA
    Posts
    486
    Quote Originally Posted by mike robinson View Post
    Iam having the same problem with the hood fan over our grill in the kitchen in food service Ihave checked amp draw way below the motor ratings as well on the heaters in the motor starter put on avoltage monitor for about aweek hood never failed , Just wondering we had to leave the door open to leave monitor hooked up maybe heat build up in enclosure?
    Make sure that all of the connections are tight on wire lugs and on the overload block heater screws. Check the temp at the overload block and look up the heater rating with the appropriate correction for the ambient temp.
    Most motors have a service factor of about 15% so the overloads should be sized (after the ambient temp correction.) at or a little above the motor FLA rating. Check to see if you have a bearing going bad, could be causing the overload after the unit has been running long enough to heat up the bearing.

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