Carrier 17 Start Up & Operation Manual

Contents

Lag Chiller Start-Up Requirements — Before the lag chillercan be started, the following conditions must be met:1. Lead chiller ramp loading must be complete.2. Lead chiller CHILLED WATER temperature must be greaterthan the CONTROL POINT plus 1/2 the WATER/BRINEDEADBAND.NOTE: The chilled water temperature sensor may be theleaving chilled water sensor, the return water sensor, thecommon supply water sensor, or the common return wa-ter sensor, depending on which options are configured andenabled.3. Lead chiller ACTIVE DEMAND LIMIT value must be greaterthan 95% of full load amps.4. Lead chiller temperature pulldown rate of the CHILLEDWATER temperature is less than 0.5° F (0.27° C) per minute.5. The lag chiller status indicates it is in CCN mode and isnot faulted. If the current lag chiller is in an alarm con-dition, then the standby chiller becomes the active lag chiller,if it is configured and available.6. The configured LAG START TIMER entry has elapsed.The LAG START TIMER shall be started when the leadchiller ramp loading is completed. The LAG START TIMERentry is accessed by selecting Lead/Lag from the Equip-ment Configuration table of the Service menu.When all of the above requirements have been met, thelag chiller is forced to a START mode. The PIC control thenmonitors the lag chiller for a successful start. If the lag chillerfails to start, the standby chiller, if configured, is started.Lag Chiller Shutdown Requirements — The following con-ditions must be met in order for the lag chiller to be stopped.1. Lead chiller COMPRESSOR MOTOR LOAD value is lessthan the lead chiller percent capacity plus 15%.NOTE: Lead chiller percent capacity = 100 – LAG PER-CENT CAPACITYThe LAG PERCENT CAPACITY value is configured onthe Lead/Lag Configuration screen.2. The lead chiller chilled water temperature is less thanthe CONTROL POINT plus 1/2 of the WATER/BRINEDEADBAND.3. The configured LAG STOP TIMER entry has elapsed. TheLAG STOP TIMER is started when the LEAVING CHILLEDWATER temperature is less than the CHILLED WATERCONTROL POINT plus 1/2 of the WATER/BRINE DEAD-BAND and the lead chiller COMPRESSOR MOTOR LOADis less than the lead chiller percent capacity plus 15%.The timer is ignored if the chilled water temperature reaches3° F (1.67° C) below the CONTROL POINT and the leadchiller COMPRESSOR MOTOR LOAD value is less thanthe lead chiller percent capacity plus 15%.FAULTED CHILLER OPERATION — If the lead chillershuts down on an alarm (*) condition, it stops communica-tion to the lag and standby chillers. After 30 seconds, the lagchiller will now become the acting lead chiller and will startand stop the standby chiller, if necessary.If the lag chiller faults when the lead chiller is also faulted,the standby chiller reverts to a stand-alone CCN mode ofoperation.If the lead chiller is in an alarm (*) condition (as shownon the LID panel), the RESET softkey is pressed to clear thealarm, and the chiller is placed in the CCN mode, the leadchiller will now communicate and monitor the RUN STA-TUS of the lag and standby chillers. If both the lag and standbychillers are running, the lead chiller will not attempt to startand will not assume the role of lead chiller until either thelag or standby chiller shuts down. If only one chiller isrunning, the lead chiller will wait for a start request from theoperating chiller. When the configured lead chiller starts, itassumes its role as lead chiller.LOAD BALANCING — When the LOAD BALANCE OP-TION is enabled, the lead chiller will set the ACTIVE DE-MAND LIMIT in the lag chiller to the lead chiller’s COM-PRESSOR MOTOR LOAD value. This value has limits of40% to 100%. When setting the lag chiller ACTIVE DE-MAND LIMIT, the CONTROL POINT shall be modified toa value of 3° F (1.67° C) less than the lead chiller’s CON-TROL POINT value. If the LOAD BALANCE OPTION isdisabled, the ACTIVE DEMAND LIMIT and the CONTROLPOINT are forced to the same value as the lead chiller.AUTO. RESTART AFTER POWER FAILURE — When anautorestart condition occurs, each chiller may have a delayadded to the start-up sequence, depending on its lead/lag con-figuration. The lead chiller does not have a delay. The lagchiller has a 45-second delay. The standby chiller has a90-second delay. The delay time is added after the chillerwater flow verification. The PIC controls ensure that the guidevanes are closed. After the guide vane position is confirmed,the delay for lag and standby chiller occurs prior to ener-gizing the oil pump. The normal start-up sequence then con-tinues. The auto. restart delay sequence occurs whether thechiller is in CCN or LOCAL mode and is intended to stag-ger the compressor motors from being energized simulta-neously. This will help reduce the inrush demands on thebuilding power system.Ice Build Control — Ice build control automatically setsthe chilled WATER/BRINE CONTROL POINT of the ma-chine from normal operation set point temperature to a tem-perature where an ice building operation for thermal storagecan be accomplished.NOTE: For ice build control to properly operate, the PICcontrols must be placed in CCN mode. See Fig. 16 and 17.The PIC can be configured for ice build operation. Con-figuration of ice build control is accomplished through en-tries in the Config table, Ice Build Setpoint table, and the IceBuild Time Schedule table. Figures 16 and 17 show how toaccess each entry.The Ice Build Time Schedule defines the period duringwhich ice build is active if the ice build option is EN-ABLED. If the Ice Build Time Schedule overlaps other sched-ules defining time, then the Ice Build Time Schedule shalltake priority. During the ice build period, the WATER/BRINE CONTROL POINT is set to the ICE BUILD SET-POINT for temperature control. The ICE BUILD RECYCLEOPTION and ICE BUILD TERMINATION entries from a screenin the Config (configuration) table provide options for ma-chine recycle and termination of ice build cycle, respec-tively. Termination of ice build can result from the ENTER-ING CHILLED WATER (brine) temperature being less thanthe ICE BUILD SETPOINT, opening the REMOTE CON-TACTS INPUT from an ice level indicator, or reaching theend of the Ice Build Time Schedule.ICE BUILD INITIATION — The Ice Build Time Scheduleprovides the means for activating ice build. The ice buildtime table is named OCCPC02S.If the Ice Build Time Schedule is OCCUPIED and the ICEBUILD OPTION is ENABLED, then ice build is active andthe following events automatically take place (unless over-ridden by a higher authority CCN device):1. Force CHILLER START/STOP to START.2. Force WATER/BRINE CONTROL POINT to the ICE BUILDSETPOINT.3. Remove any force (Auto) on the ACTIVE DEMAND LIMIT.42