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  1. #1
    Join Date
    Aug 2006
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    CT's inside of VFD's

    I took over a building that has the CT's inside of the ABB Drive Cabinets. They are for proof of run so EMS can run the drive. A bunch of them are bad and they were just locked on and forgotten about. I'm replacing them, and hate sitting there adjusting them with the drive cabinet open. I say they should be in a separate box, electricians disagree,

  2. #2
    Join Date
    Nov 2006
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    Can't you replace them with pre-set CT's?
    If you can't fix it with JB Weld, Duct Tape, and Ty Wire it has to be replaced.
    No good deed goes unpunished.
    If you want to take off friday to go fishing then make sure you train your helper right.

  3. #3
    Join Date
    Aug 2006
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    I tried some that were rated at one amp. and they wouldn't work with two wraps. Looks like I'm going to have to pull new wire from the panel to get enough wraps. I found out that the CT's aren't bad just weak. If you ramp the motor up then pull the "lock"on the computer it shows "on" I inherited a mess with these buildings, found Acuators missing, Dampers disconnected, VAV motors disconnected and the ceiling plenum taped over, etc.

  4. #4
    Join Date
    Jan 2005
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    steeler nation
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    there should be contacts on the drive to prove operation.
    IV IV IX

    use your head for something other than a hat rack.......Gerry

  5. #5
    Join Date
    Mar 2005
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    Or better yet, get a comm card/tie into the built in comm's on the VFD....
    "How it can be considered "Open" is beyond me. Calling it "voyeur-ed" would be more accurate." pka LeroyMac, SkyIsBlue, fka Freddy-B, Mongo, IndyBlue
    BIG Government = More Dependents
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  6. #6
    Join Date
    Apr 2014
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    I agree that aux drive contacts are the preferred method . Current donuts in drives are frequently problematic since they are designed to work at 60 hz.

  7. #7
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    Sep 2007
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    Motor Run contacts would be the best when the drive is commanded on they are enabled , or as previously stated 3rd party integration will give you a run status when drive is on.
    Arguing with your Boss is like wrestling with a pig in
    mud.
    After a while you realize that while you are getting
    dirty, the pig is actually enjoying it.

    It is not exactly cheating, I prefer to consider it
    creative problem solving.

    25 years ago we had Bob Hope , Steve Jobs , and Johnny Cash today we have no Hope no Jobs and no Cash !
    I can fix broke but i can't fix stupid !

  8. #8
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    I've been running so much with these buildings, I didn't even think about this. You are absolutely right about the contact in the ABB drive, as my old buildings have no CT's and there is a proof of run for the computer. I'll look at one of those drives and book on Monday to see where to land the control wire. The Heat Wheel Drive may not have a proof of run, but I fixed that one.

  9. #9
    Join Date
    Sep 2013
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    If they are ABB 550s RO 1-3 can be programmed for Run.

  10. #10
    Join Date
    Sep 2007
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    As stated below use the RO in parameter 1401 and then select #7 that will give you the started contact when commanded on and drop out when either command is lost or drive goes into fault. CT's have there purpose but if a drive gives you this option why not use it.
    Arguing with your Boss is like wrestling with a pig in
    mud.
    After a while you realize that while you are getting
    dirty, the pig is actually enjoying it.

    It is not exactly cheating, I prefer to consider it
    creative problem solving.

    25 years ago we had Bob Hope , Steve Jobs , and Johnny Cash today we have no Hope no Jobs and no Cash !
    I can fix broke but i can't fix stupid !

  11. #11
    Join Date
    Apr 2014
    Posts
    107
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    By default, relay output#2 should be setup for motor status.

  12. #12
    Join Date
    Jan 2003
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    USA
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    Quote Originally Posted by JCIman View Post
    I agree that aux drive contacts are the preferred method . Current donuts in drives are frequently problematic since they are designed to work at 60 hz.
    Stick them on the line side of the drive, preferably on the load side of the disconnect. CT always sees 60hz and even in bypass the CT will close.

    I'm not a fan of the contacts in a VFD for run status.

    1. In bypass they will not likely close.
    2. Your depending on the yahoo that setup the drive to do it correctly, or wasting your time in the manuals of the VFD of the week. I need motor run, not drive ready, vfd output on, drive at setpoint, or any of the other 50 parameters that can be setup on these outputs.
    3. Not all drives will detect belt break or motor completely disconnected. Again I'm not wasting my time to figure out how each and every drive handles this to save a $15 part.

    Comms interface is my least desired option, and I never use it for status or control. Monitoring BS only. I need a solid fan status without question. It's as important as hardwired safeties in my book. Running DX with the fan off because the comms dropped out, or some numb nut dinked with VFD, not good. Opening the economizer when its -10F and no fan could be a disaster and an insurance claim.

    What's so hard about opening a VFD and adjusting these? What are you going to do with everything that is CV and its just a starter, use the aux contacts then also??

    It takes 15sec to adjust and its a good insurance policy that has saved us more than once.
    Propagating the formula. http://www.noagendashow.com/

  13. #13
    Join Date
    Apr 2014
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    Quote Originally Posted by orion242 View Post
    Stick them on the line side of the drive, preferably on the load side of the disconnect. CT always sees 60hz and even in bypass the CT will close.

    I'm not a fan of the contacts in a VFD for run status.

    1. In bypass they will not likely close.
    2. Your depending on the yahoo that setup the drive to do it correctly, or wasting your time in the manuals of the VFD of the week. I need motor run, not drive ready, vfd output on, drive at setpoint, or any of the other 50 parameters that can be setup on these outputs.
    3. Not all drives will detect belt break or motor completely disconnected. Again I'm not wasting my time to figure out how each and every drive handles this to save a $15 part.

    Comms interface is my least desired option, and I never use it for status or control. Monitoring BS only. I need a solid fan status without question. It's as important as hardwired safeties in my book. Running DX with the fan off because the comms dropped out, or some numb nut dinked with VFD, not good. Opening the economizer when its -10F and no fan could be a disaster and an insurance claim.

    What's so hard about opening a VFD and adjusting these? What are you going to do with everything that is CV and its just a starter, use the aux contacts then also??

    It takes 15sec to adjust and its a good insurance policy that has saved us more than once.
    The ABB 550 with bypass will trigger the contacts during bypass, you can also set the output to trigger on a certain motor current. There really aren't any disadvantages. Not all drives are as capable as the ABB's though. I agree being on the line side is better.

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