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  1. #1

    Trane SWUD Current transducer problems (Maxter?)

    Is there an easy or hard way to disable the circuitry for the indoor blower current transducers? I am aware of the kit including the 1U4 board, but there must be an easier way! Trane says no, but I'm certain that someone out there has had to retro a VFD into an existing system. I could restore the old contactor if need be. But the owner would like to have the VFD leypad active at all times. I remote-mounted the new Yaskawa keypad to the front panel for his accesiblity. The unit is ridiculously "touchy" now, and will lock out on CE anywhere from 5-60 minutes of runtime. The motor is fine naturally
    I suspect a "backkick" from the drive perhaps or something like that. I could mount huge chokes on the input, but previous experience tells me that that is a very expesive gamble. Any ideas?

  2. #2
    Join Date
    Oct 2001
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    6,966
    UCP-1 ?? if this is a UCP-1 blue leds the exsisting supply fan contactor when they came in with the VFDs from Macon used it as the power contactor to supply the VFD from the UCP A07 call.the CTS stay because the UCP has to see amperage resistance for proof the fan is started....did you redip the switches for IGV/VFD SWUD might still be running configurations for Constant Volume... i need a beeeer new VFD might be pushing the CTs into a CE overload motor trip shouldn't be doing full HRz only in morning warm up or night setback..where is the staic sensing...shouldn't be over 1.5" for a SWUD on a unit wher the duct goes straight out to the space with a true return back
    "when in doubt...jump it out" http://www.youtube.com/watch?v=U1qEZHhJubY

  3. #3
    Huh? Yes we have a circa '97 board in this one(blue led's) actually they look like vacuum fluorescent to me. I miss your point about the unit driving the ct's into overload... My understanding of the circuitry is the the ct's are monitoring current draw of the IDB motor, hence I wouldn't expect them to actually do anything. The unit is operated by a 0-10vdc source (third party.. Alerton, I think) And tries to maintain a 1.5" WC static. It operated just fine on the vanes (Until they worked loose)
    Last edited by unclemikey509; 10-16-2011 at 01:13 AM. Reason: typo's

  4. #4
    Hmmm I thought a bit more about your reply Maxter. If the unit were looking for a given amount of motor current draw for what a designer anticipated for a given static pressure and did not see that, would it actually lock out? My God, if that were true I would give a real hats off to the designer. But if I were him I would also worry about putting a unit into the field that could lock out at the slightest provocation. My prior experience w/Trane says they wouldn't do somethimg like that... Hmm

  5. #5
    Join Date
    Oct 2001
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    6,966
    the SWUD connection to its VFD are the 1U4 ramping module,run signal NO,shutdown NC,and the 3 phase thru the old CV fan contactor.i'm rethinking the CV ..CT location on the L side of that fan contactor...i'm remember seeing one in the VFD panel as was when Magatek was the first into them with just one? have to dig print up to see if it was added or taken from the top of that SF contactor? do you have full blown SWUD prints showing a VFD wiring?on the current vs static Macon had no idea what static was in relation to effecting the motor.the staic probe as right on the fan housing in the 80s then was moved out onto the duct, before the first VAV...middle of the VAVs... end of the duct run. i'll get back on stuff
    "when in doubt...jump it out" http://www.youtube.com/watch?v=U1qEZHhJubY

  6. #6
    Join Date
    Oct 2001
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    that was easy........... the SWUD W/inverter print shows the olfd fan contactor retagged as the driv contactor with no CTs on the L side as with CV unit.they take 1T8 and run the T3 coming out of the VFD thru it the CT is connected into the 1U1 at A4J5 pin.again the dip switch resetting will have the module look at the single CT there and not the typical # off the old CV contactor....i made up an actual static vs DC ramp signal having read them to see how the numbers move at and below setpoint.just from experience if a space is comfortable and your last cooling signal A21 just dropped off.the VFD should not be above 30Hz the VAVs should be backed down and the static SP met and even lower is cool... typical as said 55F at 1.5" static even less on the static depending on the ducted supply turns and rises.any counter rotation prior to start will trip the unit into CE,coming out of MWUP or NSB i found the control goes back up onto the VAVs for occupied,but the VFD is at 60Hz,and can't ramp down quick enough thru the 1U4 module so you can get a CE trip there.you have to dump the VAVs during unoccupied runs and the unit is looking at the return air settings for MWUP/NSB as you see on the 1U1 just throwing out stuff i remember....biggy here if you come up on a unit with the compressor CTs tripped... it's not the compressors the condensers are fouled or check the strainers the CTs will trip them before HI Pressure is tripped...that ones free
    "when in doubt...jump it out" http://www.youtube.com/watch?v=U1qEZHhJubY

  7. #7
    Join Date
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    Maxster,

    You're giving very good advice.

    Please take a minute and apply for your AOP * before posting in AOP forum.

  8. #8
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    Oct 2001
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    i'm not a owner just answering the guys question....what's with all the rules i didn't even want PM status....... just looking to help others...
    "when in doubt...jump it out" http://www.youtube.com/watch?v=U1qEZHhJubY

  9. #9
    Join Date
    Sep 2008
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    Western PA
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    Quote Originally Posted by maxster View Post
    i'm not a owner just answering the guys question....what's with all the rules i didn't even want PM status....... just looking to help others...
    You don't need to be an owner to be an AOP Pro.

    It'll take 5 minutes to fill out the form and we won't have to hassle you anymore.


  10. #10
    Maxter, I truely appreciate your advice. To the system admin: I would take this discussion elsewhere if I were more facile with computers. Just an old guy here trying to
    make a unit run.

  11. #11
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    Oct 2001
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    hey,... i'm 58 who you calling OLD might go over to messeger in the site to continue we'll see if the prime movers dabble only trying to help out and their busting shoes
    "when in doubt...jump it out" http://www.youtube.com/watch?v=U1qEZHhJubY

  12. #12
    I am 59 so I am the older I guess. Hey,... I don't feel that old. Except recently HA!

  13. #13
    Join Date
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    Maybe I'm misunderstanding.

    Unclemikey,

    Are you a tech? If so, then this thread needs to be moved to the proper forum.

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