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

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

Contents

46The PRESTART FAULT TIMER provides a timeout if thereis a prestart alert condition that prevents a chiller fromstarting in a timely manner. If the configured lead chillerdoes not complete its start-up before the PRESTARTFAULT TIMER (a user-configured value) elapses, then thelag chiller starts, and the lead chiller shuts down. The leadchiller then monitors the lag, acting as the lead, for a startrequest. The PRESTART FAULT TIMER parameter is onthe LEADLAG screen, which is accessed from the EQUIP-MENT SERVICE table of the SERVICE menu.If the lag chiller does not achieve start-up before the PRE-START FAULT TIMER elapses, the lag chiller stops, and thestandby chiller is requested to start, if configured and ready.5.27.3 - Standby chiller configuration and operationA chiller is designated as a standby chiller when its LEAD-LAG: CONFIGURATION value on the LEADLAG screenis set to “3.” The standby chiller can operate as a replacementfor the lag chiller only if one of the other two chillers is inan alarm (*) condition (as shown on the ICVC panel). Ifboth lead and lag chillers are in an alarm (*) condition, thestandby chiller defaults to operate in CCN mode and willoperate based on its configured CCN occupancy scheduleand remote contacts input.5.27.4 - Lag chiller start-up requirementsBefore the lag chiller can be started, the following conditionsmust be met:1. Lead chiller ramp loading must be complete.. Lead chilled water temperature must be greater thanthe CONTROL POINT temperature (see the MAIN-STAT screen) plus 1/ the CHILLED WATER DEAD-BAND temperature (see the SETUP1 screen).NOTE: The chilled water temperature sensor may bethe leaving chilled water sensor, the return water sen-sor, the common supply water sensor, or the commonreturn water sensor, depending on which options areconfigured and enabled.3. Lead chiller ACTIVE DEMAND LIMIT (see theMAINSTAT screen) value must be greater than 95%of full load amps.4. Lead chiller temperature pulldown rate (TEMP PULL-DOWN DEG/MIN on the TEMP_CTL screen) of thechilled water temperature is less than 0.7 K per minutefor a sustained period of 100 seconds.5. The lag chiller status indicates it is in CCN mode andis not in an alarm condition. If the current lag chiller isin an alarm condition, the standby chiller becomes theactive lag chiller, if it is configured and available.6. The configured LAG START TIMER entry has elapsed.The LAG START TIMER starts when the lead chillerramp loading is completed. The LAG START TIMERentry is on the LEADLAG screen, which is accessedfrom the EQUIPMENT SERVICE table of theSERVICE menu.When all the above requirements have been met, the lagchiller is commanded to a STARTUP mode (indicated by“CONTRL” flashing next to the CHILLER START/STOPparameter in the MAINSTAT screen). The PIC III controlthen monitors the lag chiller for a successful start. If the lagchiller fails to start, the standby chiller, if configured, is started.5.27.5 - Lag chiller yhutdown RequirementsThe following conditions must be met in order for the lagchiller to be stopped.1. Lead chiller AVERAGE LINE CURRENT or MOTORPERCENT KILOWATTS (on the MAINSTATscreen) is less than the lead chiller percent capacity.NOTE: Lead Chiller Percent Capacity = 115 – LAG% CAPACITY. The LAG % CAPACITY parameteris on the LEADLAG screen, which is accessed fromthe EQUIPMENT SERVICE table on the SERVICEmenu.. The lead chiller chilled water temperature is less thanthe CONTROL POINT temperature (see the MAIN-STAT screen) plus 1/ the CHILLED WATER DEAD-BAND temperature (see the SETUP1 screen).3. The configured LAG STOP TIMER entry has elapsed.The LAG STOP TIMER starts when the lead chillerchilled water temperature is less than the chilled waterCONTROL POINT plus 1/ of the CHILLED WATERDEADBAND and the lead chiller compressor motorload (MOTOR PERCENT KILOWATT or AVERAGELINE CURRENT on the MAINSTAT screen) is lessthan the lead chiller percent capacity.NOTE: Lead Chiller Percent 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.5.27.6 - Faulted chiller operationIf the lead chiller shuts down because of an alarm (*) condi-tion, it stops communicating to the lag and standby chillers.After 30 seconds, the lag chiller becomes the acting leadchiller and starts and stops the standby chiller, if necessary.If the lag chiller goes into alarm when the lead chiller isalso in alarm, the standby chiller reverts to a stand-aloneCCN mode of operation.If the lead chiller is in an alarm (*) condition (as shown onthe ICVC panel), press the ReSet softkey to clear thealarm. The chiller is placed in CCN mode. The lead chillercommunicates and monitors the RUN STATUS of the lagand standby chillers. If both the lag and standby chillers arerunning, the lead chiller does not attempt to start and doesnot assume the role of lead chiller until either the lag orstandby chiller shuts down. If only one chiller is running,the lead chiller waits for a start request from the operatingchiller. When the configured lead chiller starts, it assumesits role as lead chiller.If the lag chiller is the only chiller running when the leadchiller assumes its role as a lead chiller then the lag chillerwill perform a RECOVERY START REQUEST (LL_MAINT screen). The lead chiller will start up when thefollowing conditions are met.1. Lag chiller ramp loading must be complete.. Lag CHILLED WATER TEMP (MAINSTAT screen)is greater than CONTROL POINT plus 1/ theCHILLED WATER DEADBAND temperature.3. Lag chiller ACTIVE DEMAND LIMIT value mustbe greater than 95% of full load amps.