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  1. #1
    Join Date
    Jan 2012
    Location
    Pakistan
    Posts
    20

    York Centrifugal Chiller Half phase fault

    We have three York centrifugal chillers with the following spec
    Series YT Codepak
    Unit Model YTH3J3E35COG
    Refrigerant R123
    Capacity 500 Tons
    Compressor Model YDTL.126
    Starter SSS 26L-50A (LCSSS)

    One of them was under maintenance and we replaced its shaft seal. Now when it was taken again in service it has started tripping on 'half phase' fault.

    I've changed the trigger board with a new one and also swapped it with the chiller which is working fine but to no avail.

    Took the resistance readings of each thyristor as well as the J6 to J11 points on the cards. Found one thyristor short and replaced it. Now all the resistances of the thyristors are between 15 and 20 ohms as per the York Manual. Secondly, each of the points on the board has a resistance of around 200 ohm as per the board.

    What could be the issue here?

    The chillers have been service since 1996 and before maintenance it wasn't any half phase fault.
    Thanks

  2. #2
    Join Date
    Dec 2008
    Location
    Dixiana, AL
    Posts
    2,611
    This is not necessarily a subject for the open forum. Get your post count up and go pro.
    And what are you calling a thyristor?

  3. #3
    Join Date
    Jan 2012
    Location
    Pakistan
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    Quote Originally Posted by klove View Post
    This is not necessarily a subject for the open forum. Get your post count up and go pro.
    And what are you calling a thyristor?
    SCR

  4. #4
    Join Date
    Mar 2007
    Posts
    63
    check for broken SCR Gate Wire. There are 2 SCR Gate Wires for each Phase.
    If not broken SCR Gate wire, swap LOGIC Board with one on the working chiller to try.

  5. #5
    Join Date
    Sep 2007
    Location
    Somewhere in the world.
    Posts
    1,618

    Half Phase Trip Fault

    DETAILS
    Locate your copy of 160.46-OM3.1 (SB9 & SB11), and then replace it with this literature supplement!
    When troubleshooting a half-phase trip, it is first necessary to determine if the situation is a real event caused by a
    starter malfunction, or a false trip caused by electrical abnormalities. We have been seeing an increasing number
    of false trips lately, so we suggest you rule-out the typical false trip conditions fi rst. The three known causes of
    false trips are:
    1) High Line Voltage, greater than 500VAC on a 460VAC nominal system, for example. More than 10% above
    nominal.
    2) Large Variable Speed Drives on same power distribution, or many smaller drives in combination. Most VSD’s
    create voltage distortion, which distorts our chillers motor’s waveform.
    3) Significant Current Imbalance, greater than 15% from highest leg to the lowest leg. Look at the Control Panel’s
    display just prior to tripping. Note: the highest and lowest values, subtract to get the difference, and divide this
    number by the value of the lowest leg. If the answer is .15 or more, current imbalance is likely the cause. A
    1.5% voltage imbalance will create a 15% or greater current imbalance. The exact amount of current imbalance
    varies with motor load (%FLA), and increases as the motor unloads.
    If tripping is caused by one of these conditions, it would be best to correct the problem at the source, i.e. change
    transformer taps to lower voltage, put fi lters on VSD’s, or balance out single phase loads to bring voltage balance
    to within 1%. If this is not possible, you may have no choice but to eliminate the 1/2 phase circuit. On older
    rev. ‘D’ through rev. ‘F’ boards, you will need to solder a wire jumper as shown on Fig. 1. On (Rev G) and
    newer starter logic boards, there is a jumper wire, JP1, located approximately 1.5 inch below the large
    black heatsink in the upper right corner. Cut this jumper to disable the 1/2 phase circuit.
    If none of the three above conditions exist, you likely have a real problem in the LCSSS, and should troubleshoot
    the starter. The 1/2 phase indicator is intended to signify that one of the six SCR’s is not fi ring. Most common
    problem areas are the trigger board, connections from the 3-wye to the trigger, and connections from the trigger to
    the SCR’s.
    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 !

  6. #6
    Join Date
    Jan 2012
    Location
    Pakistan
    Posts
    20
    Quote Originally Posted by york56 View Post
    DETAILS
    Locate your copy of 160.46-OM3.1 (SB9 & SB11), and then replace it with this literature supplement!
    When troubleshooting a half-phase trip, it is first necessary to determine if the situation is a real event caused by a
    starter malfunction, or a false trip caused by electrical abnormalities. We have been seeing an increasing number
    of false trips lately, so we suggest you rule-out the typical false trip conditions fi rst. The three known causes of
    false trips are:
    1) High Line Voltage, greater than 500VAC on a 460VAC nominal system, for example. More than 10% above
    nominal.
    2) Large Variable Speed Drives on same power distribution, or many smaller drives in combination. Most VSD’s
    create voltage distortion, which distorts our chillers motor’s waveform.
    3) Significant Current Imbalance, greater than 15% from highest leg to the lowest leg. Look at the Control Panel’s
    display just prior to tripping. Note: the highest and lowest values, subtract to get the difference, and divide this
    number by the value of the lowest leg. If the answer is .15 or more, current imbalance is likely the cause. A
    1.5% voltage imbalance will create a 15% or greater current imbalance. The exact amount of current imbalance
    varies with motor load (%FLA), and increases as the motor unloads.
    If tripping is caused by one of these conditions, it would be best to correct the problem at the source, i.e. change
    transformer taps to lower voltage, put fi lters on VSD’s, or balance out single phase loads to bring voltage balance
    to within 1%. If this is not possible, you may have no choice but to eliminate the 1/2 phase circuit. On older
    rev. ‘D’ through rev. ‘F’ boards, you will need to solder a wire jumper as shown on Fig. 1. On (Rev G) and
    newer starter logic boards, there is a jumper wire, JP1, located approximately 1.5 inch below the large
    black heatsink in the upper right corner. Cut this jumper to disable the 1/2 phase circuit.
    If none of the three above conditions exist, you likely have a real problem in the LCSSS, and should troubleshoot
    the starter. The 1/2 phase indicator is intended to signify that one of the six SCR’s is not fi ring. Most common
    problem areas are the trigger board, connections from the 3-wye to the trigger, and connections from the trigger to
    the SCR’s.
    Thanks for the reply. I dont have a copy of this supplement and cant find it online either, can you email me that?

    Thanks again

  7. #7
    Join Date
    Jan 2012
    Location
    Pakistan
    Posts
    20
    Quote Originally Posted by w~p View Post
    check for broken SCR Gate Wire. There are 2 SCR Gate Wires for each Phase.
    If not broken SCR Gate wire, swap LOGIC Board with one on the working chiller to try.
    Done the swapping already. Two SCRs were indeed short. One had a shorted gate and the other was anode to cathod short. Now all are OK but still the half phase.

    Swapped the trigger logic board as well without success. We have three of these chillers, same model, spec, supply source but this has been nagging since its shaft seal was done.

  8. #8
    Join Date
    Sep 2007
    Location
    Somewhere in the world.
    Posts
    1,618
    Quote Originally Posted by snsici View Post
    Thanks for the reply. I dont have a copy of this supplement and cant find it online either, can you email me that?

    Thanks again
    You won't find it online and you profile is missing alot of information regarding yourself.
    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 !

  9. #9
    Join Date
    Jan 2012
    Location
    Pakistan
    Posts
    20
    Quote Originally Posted by york56 View Post
    You won't find it online and you profile is missing alot of information regarding yourself.
    Updated it.

  10. #10
    Join Date
    Sep 2007
    Location
    Somewhere in the world.
    Posts
    1,618
    Quote Originally Posted by snsici View Post
    Updated it.
    Check your mail.
    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
    Jan 2012
    Location
    Pakistan
    Posts
    20
    Quote Originally Posted by york56 View Post
    Check your mail.
    Haven't received anything yet.

  12. #12
    Join Date
    Mar 2007
    Posts
    63
    Quote Originally Posted by york56 View Post
    DETAILS
    Locate your copy of 160.46-OM3.1 (SB9 & SB11), and then replace it with this literature supplement!
    Please let me have them too.
    Thank you

  13. #13
    Join Date
    Jan 2012
    Location
    Melbourne
    Posts
    12

    York yrvc

    Hi do u also have the service manual 160.81.m1 I'm have trouble with this chiller failing on low differential oil pressure! Any hints

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