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  1. #1
    Join Date
    Jul 2001
    Posts
    180
    I got a 23XL Carrier screw chiller that just had it’s Benshaw soft starter replaced (complete RSM6B unit). The chiller was down approximately 5 weeks. Upon attempting startup, the chiller faults on “High Condenser Pressure”. The condenser pressure read about 80 psi, which coincides with the oil pressure reading. The discharge transducer is good. The threshold value is set at 230 psi. The discharge pressure switch and the CW and CDW differential pressure switches were closed. There were no faults displayed on the starter. Benshaw shall be contacted on Monday. Does anyone know what the problem may be? Thanks.

  2. #2
    Join Date
    Jan 2005
    Posts
    175
    Air cooled or water cooled? Fans running? Water flow? Water valves open?

  3. #3
    Join Date
    Jul 2001
    Posts
    180
    Water cooled. CW and CDW differential pressure switches were closed.

  4. #4
    Join Date
    Jun 2004
    Location
    BR,LA
    Posts
    256
    HCFC-22 or HFC-134a

  5. #5
    Join Date
    Jun 2004
    Location
    BR,LA
    Posts
    256
    [HIGH CONDENSER PRESSURE] Condenser Refrigerant Pressure VALUE exceeded limit of [LIMIT]*.
    Check condenser water and transducer.
    Check for high condenser water temperature.
    Check transducer accuracy.
    how do i know, that you know, the transducer is accurate. what did u do to check it?

    [Edited by joeywpittman on 03-27-2005 at 05:37 PM]

  6. #6
    Join Date
    Jun 2004
    Location
    BR,LA
    Posts
    256
    Capacity Overrides (Table 5) — These can prevent
    some safety shutdowns caused by exceeding motor amperage
    limit, refrigerant low temperature safety limit, motor high
    temperature safety limit, and condenser high pressure limit.
    In all cases there are 2 stages of compressor slide valve
    control.
    1. The slide valve is held from closing further, and the status
    line on the LID indicates the reason for the override.
    2. The slide valve is opened until condition decreases below
    the first step set point, and then the valve is released
    to normal capacity control.
    Whenever the motor current demand limit set point is reached,
    it activates a capacity override, again with a two-step process.
    Exceeding 110% of the rated load amps for more than
    10 seconds will initiate a safety shutdown.

  7. #7
    Join Date
    Jul 2001
    Posts
    180
    Using R-22

    Condenser water pump running and valves open. Condenser water proof of flow differential pressure switch closed. Discharge transducer was replaced (although 80 psi should not have signaled an alarm in the first place). Also did a system transducer auto check.

    I should make it clear that the unit has never actually started since the soft starter replacement. The unit alarms when attempting to start up. The current condenser pressure flashes on the LID and the message “High Condenser Pressure” is displayed.

    I suspect that maybe the alarm message may not accurately define the true problem. Reason: I use to get a nuisance alarm that stated “Starter Auxiliary Run Contactor Fault”, which is actually not applicable to an electronic soft starter. But the alarm message did tell me that there was some type of problem or glitch with the soft starter.

    Thank you for your responses.

  8. #8
    Join Date
    Jun 2004
    Location
    BR,LA
    Posts
    256
    activate the Capacity Override for high condensing pressure

  9. #9
    Join Date
    Jul 2001
    Posts
    180
    joeywpittman

    I'll look into the Capacity Override first thing tomorrow. Thanks

  10. #10
    Join Date
    Oct 2004
    Posts
    115
    Here's the deal:

    When the controls try to start the chiller, they close the 1CR control relay which is in the starter and tells the benshaw unit to start. The controls then look for a start initiated reply back from the starter within 2 sec., which is the 1M contact closure. If the controls do not see this 1M contact closure, then they give the high condenser pressure alarm, because there is also a condenser high pressure switch in the 1CR circuit.

    bottom line: Look for a reason why the benshaw starter is not starting

  11. #11
    Join Date
    Jul 2001
    Posts
    180
    techtalker


    Although my SCR soft starter does not utilize 1CR and 1M relay/contractor, I believe that you may be right that the problem is at the starter. Will be looking further. Thank you.


  12. #12
    Join Date
    Jun 2004
    Location
    BR,LA
    Posts
    256

  13. #13
    Join Date
    Mar 2005
    Location
    Dover, Pa.
    Posts
    192
    Originally posted by techtalker
    Here's the deal:

    When the controls try to start the chiller, they close the 1CR control relay which is in the starter and tells the benshaw unit to start. The controls then look for a start initiated reply back from the starter within 2 sec., which is the 1M contact closure. If the controls do not see this 1M contact closure, then they give the high condenser pressure alarm, because there is also a condenser high pressure switch in the 1CR circuit.

    bottom line: Look for a reason why the benshaw starter is not starting

    pbcb,
    Here is your answer-----I had the same thing happen to me too.....turned out to be what techtalker said here.

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