Carrier 19XRV Start-up, Operation And Maintenance Instructions Manual

Also see for AquaEdge 19XRV series: Start-up and service instructions Installation instructions Start-up, operation and maintenance instructions Start-up and service instructions User manual

Carrier 19XRV Start-up, Operation And Maintenance Instructions Manual Manual pdf 45 page image

Lead/Lag Chiller Configuration and Operation• A chiller is designated the lead chiller when itsLEADLAG: CONFIGURATION value on the LEAD-LAG screen is set to "1 ."• A chiller is designated the lag chiller when itsLEADLAG: CONFIGURATION value is set to "2."• A chiller is designated as a standby chiller when itsLEADLAG: CONFIGURATION value is set to "3."• A value of "0" disables the lead/lag designation of achiller. This setting should also be used when "normal"operation without regard to lead/lag rules is desired (inLOCAL or CCN mode).When configuring the LAG ADDRESS value on theLEADLAG screen of chiller "A" enter the address of thechiller on the system which will serve as lag when/if chiller"A" is configured as lead. For example, if you ale configuringchiller A, enter the address for chiller B as file lag address. [fyou ale configuring chiller B, enter the addiess for chiller A asthe lag address. This makes it easier to rotate the lead and lagchillers. Note that only the lag and standby chiller addressesspecified in the configmed lead chiller's table me relevant at agiven time.If file address assignlnents in the LAG ADDRESSand STANDBY ADDRESS parameters conflict, the lead/lagfunction is disabled and an alert (!) message displays. Forexample, if the LAG ADDRESS matches the lead chiller'saddiess, the lead/lag will be disabled and an alert (!) messagedisplayed. The lead/lag maintenance screen (LL_MAINT) dis-plays the message 'INVALID CONFIG' in the LEADLAG:CONFIGURATION and CURRENT MODE fields.The lead chiller responds to normal start/stop controls suchas the occupancy schedule, a forced start or stop, and lemotestart contact inputs. After completing stmt-up and ramploading, the PIC III evaluates the need for additional capacity.If additional capacity is needed, the PIC III initiates the stmt-upof the chiller configured at the LAG ADDRESS. If the lagchiller is faulted (in _darm) or is in the OFF or LOCAL modes,the chiller at file STANDBY ADDRESS (if configured) isrequested to start. After the second chiller is stmted and isrunning, the lead chiller monitors conditions and evaluateswhether the capacity has been reduced enough for the leadchiller to sustain the system alone. If the capacity is reducedenough for file lead chiller to sustain the CONTROL POINTtemperatures alone, then the operating lag chiller is stopped.If the lead chiller is stopped in CCN mode for tiny reasonother than an almm (*) condition, the lag and standby chillersare also stopped. If the configured lead chiller stops for analarln condition, the configured lag chiller takes the leadchiller's place as the lead chillel: and the standby chiller servesas the lag chillel:The PRESTART FAULT TIMER provides a timeout ifthere is a prestart alert condition that prevents a chiller fromstarting in a timely mannel: If the configured lead chiller doesnot complete its start-up before the PRESTART FAULTTIMER (a user-configured v_due) elapses, then the lag chillerstarts, and the lead chiller shuts down. The lead chiller thenmonitors the lag, acting as the lead, for a stm't request. ThePRESTART FAULT TIMER parameter is on the LEADLAGscreen, which is accessed fi_m the EQUIPMENT SERVICEtable of the SERVICE menu.If the lag chiller does not achieve start-up before thePRESTART FAULT TIMER elapses, the lag chiller stops, andthe standby chiller is requested to start, if configured and ready.Standby Chiller Configuration and Operation -- A chiller isdesignated as a standby chiller when its LEADLAG: CONFIG-URATION wdue on the LEADLAG screen is set to "3." Thestandby chiller can operate as a replacement for the lag chilleronly if one of the other two chillel_ is in an alarm (*) condition(as shown on file ICVC panel). If both lead and lag chillersme in an alarm (*) condition, the standby chiller defaults tooperate in CCN mode, will operate based on its configuredCCN occupancy schedule and remote contacts input.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 chilled water temperature must be greater than theCONTROL POINT temperature (see the MAINSTATscreen) plus 1/2 the CHILLED WATER DEADBANDtemperature (see the SETUPI screen).NOTE: The chilled water telnperature sensor may be theleaving chilled water sensor, the return water sensol: thecommon supply water sensor, or the common returnwater sensor, depending on which options are configuredand enabled.3. Lead chiller ACTIVE DEMAND LIMIT (see the MAIN-STAT screen) value must be greater than 95% of lhll loadmnps.4. Lead chiller telnperature pulldown rate (TEMP PULL-DOWN DEG_IN on the TEMP_CTL screen) of thechilled water temperature is less than 0.5 ° F (0.27 ° C) perminute for a susttdned period of 100 seconds.5. The lag chiller status indicates it is in CCN mode and isnot in an alarm condition. If the current lag chiller is in tinalarm condition, the standby chiller becomes the activelag chiller, if it is configured and available.6. The configured LAG START TIMER entry has elapsed.The LAG START TIMER stmts when the lead chiller rmnploading is completed. The LAG START TIMER entry ison the LEADLAG screen, which is accessed from theEQUIPMENT SERVICE table of the SERVICE menu.When all the above requirements have been met, file lagchiller is commanded to a STARTUP mode (indicated by"CONTRL" flashing next to the CHILLER START/STOPparameter in the MAINSTAT screen). The PIC III control thenmonitors the lag chiller for a successful stark If the lag chillerfails to start, the standby chiller, if configured, is started.Lag Chiller Shutdown Requirements -- The following condi-tions must be met in order for the lag chiller to be stopped.1. Lead chiller AVERAGE LINE CURRENT or MOTORPERCENT KILOWATTS (on the MAINSTAT screen) isless than the lead chiller percent capacity.NOTE: Lead Chiller Pement Capacity = 115 - LAG %CAPACITY The LAG % CAPACITY parameter is on theLEADLAG screen, which is accessed from the EQUIP-MENT SERVICE table on the SERVICE menu.2. The lead chiller chilled water temperature is less than theCONTROL POINT temperature (see the MAINSTATscreen) plus I/2 the CHILLED WATER DEADBANDtemperature (see the SETUPI screen).3. The configured LAG STOP TIMER entry has elapsed.The LAG STOP TIMER starts when the lead chillerchilled water temperature is less than file chilled waterCONTROL POINT plus 1/2 of the CHILLED WATERDEADBAND trod the lead chiller compressor motor load(MOTOR PERCENT KILOWATT or AVERAGE LINECURRENT on the MAINSTAT screen) is less than theLead Chiller Percent Capacity.NOTE: Lead Chiller Percent Capacity = 115 - LAG %CAPACITY The LAG % CAPACITY parameter is on theLEADLAG screen, which is accessed fi_>mthe EQUIPMENTSERVICE table on the SERVICE menu.45