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  1. #1
    Join Date
    Jul 2001
    Posts
    180
    I have 2 York centrifugal chillers with SS starters (I believe 14L). Unit #1 has been running fine and #2 was the backup chiller. I rotated chillers and started #2. After approx. 5 min., the unit shut down on Half Phase. I tried it again and the same thing happened. I checked the York Operation, Start-up and Service instruction and referenced the troubleshooting flow chart for Half Phase. It states that if the chiller runs, the “Shutdown was caused by AC powerline disturbance”. I have several questions.

    1) If I have a powerline disturbance but the other chiller runs, what should I be looking for?
    2) The flow chart rules out a bad SCR or a bad trigger board because the unit initially runs. Couldn’t these components still be faulty?
    3) Any suggestions as to my next steps to be taken?

    I appreciate your help!

  2. #2
    Join Date
    Aug 2000
    Location
    USA
    Posts
    4,979
    There is a service bullitan to repair this if its not a real problem and is a nuisance trip. I believe you add a resister or mov to the unit.

  3. #3
    Join Date
    Jul 2001
    Posts
    180
    I read a reply from RichardL from previous post that mentioned "Ferrite Beads" as a solution to RF interference. Since this just started happening and the since the problem is not intermittent, I suspect this is not a nuisance trip (but will not rule out).

    I'm hoping RichardL might be able to provide additional info.


    Thanks absrbrtek

  4. #4
    Join Date
    Aug 2000
    Location
    Austell, Ga.
    Posts
    1,292
    pbcd;
    Sorry bout the sloooooow response..
    By all means install 1 or even better two ferrite beads on the Communication cable from the SSS to the micro-board.
    Should that not cure the problem make "Certain" that the shield on the Interconnecting cable is not making contact with any source ground....
    get Reaaaaal close and personal with the connector on the SSS and make certain that a pin(s) has not backed out any...
    This is a problem that will drive one Nuts....
    Lastly, the control x'former wiring terminal block up in the right corner is sometimes not grounded as shown on the prints...
    Lastly.....
    After powering unit down, the SCR's (Six of them) can be checked with a ohm-meter by comparing anode-Cathode& Gate Resistances to each other....
    DO NOT USE A ANALOG OHMETER ON THE GATE CONNECTOR!!!
    The SCR's normally fail in the Conducting mode and will give a "Half-Phase" fault when it does...
    Let us know what you find please..
    Ain't "None" of us as smart as "All" of us..

  5. #5
    Join Date
    Jun 2002
    Location
    ga
    Posts
    45
    I have one that one of the leg flirts with trip point on current imbalance.The voltage is within 2% ,and the trigger board checks out.I did what the bulliten says with the jumper.If I am not mistakeing,the current has to be out 30% for 20 min at or over 80% motor current.Half phase has to do with the cycles but I pretty sure half phase will come up on current and voltage imbalance too.

  6. #6
    Join Date
    Jul 2001
    Posts
    180
    Thanks for the responses. Sorry I took so long to respond back. Been working late. I spoke with an old timer that previously worked on these units. He said years ago York told him that the unit could fault on Half Phase if the unit is surging (don't know how it could be related). My unit was indeed surging when I started it up. I noticed the purge pump was not working and the condenser approach is high (16 degrees). I repaired the pump and ran the unit for 24 hours at a current limit of 77%. I unit did not trip. So in this particular case I assume the Half Phase is somehow related to the surging.

    RichardL, I have 3 questions if you don't mind.
    -- Have you heard of surging causing this fault?
    -- What is the design approach and limits for these units?
    -- On the purge pump (original design) there is a shut off safety float valve right before the transducer and purge solenoid. What drops this float back down? It sort of wedges in the tapered port and does not drop down on it's own. I assume once it's up there the gas pressure in the vessel I will tend to drive it in even tighter. I realize that this is a safety valve and not an operational valve.

    If I remember I will bring home the chiller model number info. Thanks for your help.


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