Carrier 17 Start Up & Operation Manual

Contents

Failure to verify any of the requirements up to this pointwill result in the PIC aborting the start and displaying theapplicable pre-start mode of failure on the LID default screen.A pre-start failure does not advance the starts in 12 hourscounter. Any failure after the 1CR relay has energized re-sults in a safety shutdown, energizes the alarm light, and dis-plays the applicable shutdown status on the LID display.Shutdown Sequence — Shutdown of the machine canoccur if any of the following events happen:• the STOP button is pressed for at least one second (thealarm light will blink once to confirm stop command)• recycle condition is present (see Chilled Water Recycle Modesection)• time schedule has gone into UNOCCUPIED mode• remote contact opens• the start/stop status is overridden to stop from the CCNnetwork or the LIDWhen a stop signal occurs, the shutdown sequence firststops the compressor by deactivating the start relay. A statusmessage of ‘‘SHUTDOWN IN PROGRESS, COMPRES-SOR DEENERGIZED’’ is displayed. Compressor ontimeand service ontime stop. The guide vanes are then broughtto the closed position. The oil pump relay and the chilledwater/brine pump relay are shut down 60 seconds after thecompressor stops. The condenser water pump will be shutdown when the CONDENSER REFRIGERANT TEMP is lessthan the CONDENSER PRESSURE OVERRIDE minus 5 psi(34 kPa) or is less than or equal to the ENTERING CON-DENSER WATER TEMP plus 3° F (2° C). The stop-to-starttimer will now begin to count down. If the start-to-start timeris still greater than the value of the start-to-stop timer, thenthis time is now displayed on the LID.Certain conditions during shutdown will change thissequence:• if the COMPRESSOR MOTOR LOAD is greater than 10%after shutdown, or the starter contacts remain energized,the oil pump and chilled water pump remain energized andthe alarm is displayed• if the ENTERING CONDENSER WATER temperature isgreater than 115 F (46 C) at shutdown, the condenser pumpwill be deenergized after the 1CR compressor start relay• if the machine shuts down due to low refrigerant tempera-ture, the chilled water pump will stay running until theLEAVING CHILLED WATER is greater than CONTROLPOINT, plus 5° F (3° C)Automatic Soft Stop Amps Threshold — The SOFTSTOP AMPS THRESHOLD closes the guide vanes of thecompressor automatically when a non-recycle, non-alarm stopsignal occurs before the compressor motor is deenergized.If the STOP button is pressed, the guide vanes close to apreset amperage percent or until the guide vane is less than2% open. The compressor will then shut off.If the machine enters an alarm state or if the compressorenters a RECYCLE mode, the compressor will be deener-gized immediately.To activate SOFT STOP AMPS THRESHOLD, view thebottom of Service1 table. Set the SOFT STOP AMPS THRESH-OLD value to the percentage amps at which the motor willshut down. The default setting is 100% amps (no Soft Stop).When the SOFT STOP AMPS THRESHOLD is being ap-plied, a status message ‘‘SHUTDOWN IN PROGRESS, COM-PRESSOR UNLOADING’’ is shown.Chilled Water Recycle Mode — The machinemay cycle off and wait until the load increases to restartagain when the compressor is running in a lightly loadedcondition. This cycling of the chiller is normal and is knownas recycle. A recycle shutdown is initiated when any of thefollowing conditions are true:• when in LCW control, the difference between the LEAV-ING CHILLED WATER temperature and ENTERINGCHILLED WATER temperature is less than the RECYCLESHUTDOWN DELTA T (found in the Service1 table) andthe LEAVING CHILLED WATER TEMP is below the CON-TROL POINT, and the CONTROL POINT has not in-creased in the last 5 minutes• when ECW CONTROL OPTION is enabled, the differencebetween the ENTERING CHILLED WATER temperatureand the LEAVING CHILLED WATER temperature is lessthan the RECYCLE SHUTDOWN DELTA T (found in theService1 table) and the ENTERING CHILLED WATER TEM-PERATURE is below the CONTROL POINT, and the CON-TROL POINT has not increased in the last 5 minutes• when the LEAVING CHILLED WATER temperature is within3° F (2° C) of the BRINE REFRIG TRIPPOINTWhen the machine is in RECYCLE mode, the chilled wa-ter pump relay remains energized so that the chilled watertemperature can be monitored for increasing load. The re-cycle control uses RECYCLE RESTART DELTA T to checkwhen the compressor should be restarted. This is an operator-configured function which defaults to 5° F (3° C). This valueis viewed/modified on the Service1 table. The compressorwill restart when:• in LCW CONTROL the LEAVING CHILLED WATER tem-perature is greater than the CONTROL POINT plus the RE-CYCLE RESTART DELTA T; or• in ECW CONTROL, the ENTERING CHILLED WATERtemperature is greater than the CONTROL POINT plus theRECYCLE RESTART DELTA TOnce these conditions are met, the compressor shall ini-tiate a start-up, with a normal start-up sequence.An alert condition may be generated if 5 or more RE-CYCLE STARTUPs occur in less than 4 hours. This exces-sive recycling can reduce machine life. Compressor recyclingdue to extremely low loads should be reduced. To reducecompressor recycling, use the time schedule to shut the ma-chine down during low load operation or increase the ma-chine load by running the fan systems. If the hot gas bypassis installed, adjust the values to ensure that hot gas is ener-gized during light load conditions. Increase the RECYCLERESTART DELTA T on the Service1 table to lengthen thetime between restarts.The machine should not be operated below design mini-mum load without a hot gas bypass installed on themachine.Safety Shutdown — A safety shutdown is identical toa manual shutdown with the exception that the LID will dis-play the reason for the shutdown, the alarm light will blinkcontinuously, and the spare alarm contacts will be ener-gized. A safety shutdown requires that the RESET softkeybe pressed in order to clear the alarm. If the alarm is stillpresent, the alarm light will continue to blink. Once the alarmis cleared, the operator must press the CCN orLOCAL softkeys to restart the machine.Do not reset starter loads or any other starter safety for30 seconds after the compressor has stopped. Voltageoutput to the compressor start signal is maintained for10 seconds to determine starter fault.461197→→→