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  1. #1
    Join Date
    Sep 2010
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    66

    ABB ACH550 drive overcurrent fault

    I have a building with four Carrier 48AJ RTU's. I believe installed in 2005. They each have an ABB ACH550-UH 10 hp drive. There are nuisance trips of "overcurrent" on these units. Different unit,different day,dfferent time. I was told this has been happening since the building was built. I have worked with ABB tech support. I checked and changed perameters per their advice(Accel,decel,volts,amps,hp etc.) I have an active case number open with ABB. I have talked with them four times now. They even had me put slightly different perameters in two of the drives.The problem still exists. These units are on a VAV system. It seems to happen at morning warm up or during setback when fan cycles. They may operate for two months o.k. then fail twice in a week. Fails .....different unit,different days.But,typically only one random unit will fail. I usually go to the jobsite one day a month. The customer logs the failures and manually resets unit by cycling power. Any help would be appreciated. Thanks

  2. #2
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,667
    How about a complete model number? Does it have a static pressure transducer? How come the ABB guy can't fix it?
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  3. #3
    Join Date
    Jan 2002
    Location
    Fort Worth\Dallas, Texas
    Posts
    1,694
    What is the deceleration time set to? If it is not set too low and the motor parameters are correct I would suspect a design and or control issue causing this.

    Can the customer trend anything on the drives and the units? If so this might give you a better idea of whats going on. I would watch it in a morning warmup situation and see if the drives are reaching the current limit.
    Go Rangers!

  4. #4
    Join Date
    Sep 2003
    Location
    Western PA
    Posts
    1,339
    It's the drive. Change it out. I had same issue. I didn't want to believe it was the drive. I learned the hard way.
    Local 449?

  5. #5
    Join Date
    Jan 2002
    Location
    Fort Worth\Dallas, Texas
    Posts
    1,694
    Quote Originally Posted by targetman View Post
    It's the drive. Change it out. I had same issue. I didn't want to believe it was the drive. I learned the hard way.
    If it was one drive maybe, but I doubt all four of them are bad with the same problem.
    Go Rangers!

  6. #6
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
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    3,667
    Quote Originally Posted by targetman View Post
    It's the drive. Change it out. I had same issue. I didn't want to believe it was the drive. I learned the hard way.
    Actually it's the motor , with the motor sitting pat the evaporator condensation is building up inside the motor and that's the theory. Plus I can see it happening more when the unit shuts down.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  7. #7
    Join Date
    Sep 2003
    Location
    Western PA
    Posts
    1,339
    Quote Originally Posted by lwarren View Post
    If it was one drive maybe, but I doubt all four of them are bad with the same problem.
    In my case the drive was bad from start-up.
    Local 449?

  8. #8
    Join Date
    Jan 2002
    Location
    Fort Worth\Dallas, Texas
    Posts
    1,694
    I would think moisture would cause a ground fault.
    Go Rangers!

  9. #9
    Join Date
    Jun 2006
    Location
    New Jersey
    Posts
    4,288
    Quote Originally Posted by targetman View Post
    It's the drive. Change it out. I had same issue. I didn't want to believe it was the drive. I learned the hard way.
    4 bad drives?


    Just set 3104 to "1" and be done with it.

  10. #10
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
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    3,667
    Quote Originally Posted by lwarren View Post
    I would think moisture would cause a ground fault.
    Not always.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  11. #11
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,667
    Quote Originally Posted by lwarren View Post
    I would think moisture would cause a ground fault.
    The very first units had Toshiba drives and they did the same thing. I always replace motor with a TEFC motor.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  12. #12
    Join Date
    May 2004
    Location
    SE Pennsylvania
    Posts
    829
    Quote Originally Posted by thegoodlistener View Post
    Actually it's the motor , with the motor sitting pat the evaporator condensation is building up inside the motor and that's the theory. Plus I can see it happening more when the unit shuts down.
    I agree with this statement had a job that 4 starting tripping days apart, changed motors to TEFC and never had issue afterwards. Same story, open ABB ticket, parameter changes, even had a rep come out.

  13. #13
    Join Date
    Oct 2011
    Location
    MASON NECK VA
    Posts
    17
    change motor to drive compliant motor no more problems. Had the same thing new drive old motor would trip every few days till motor was replaced. Meg the motor you will see

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