Carrier 19XR User 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

39(see wiring diagrams or certified drawings). The temperaturesensor must be wired to terminal J4-13 and J4-14. To configureReset Type 2, enter the temperature of the remote sensor at thepoint where no temperature reset will occur (REMOTE TEMP–> NO RESET). Next, enter the temperature at which the fullamount of reset will occur (REMOTE TEMP –> FULLRESET). Then, enter the maximum amount of reset required tooperate the chiller (DEGREES RESET). Reset Type 2 can nowbe activated.RESET TYPE 3 — Reset Type 3 is an automatic chilled watertemperature reset based on cooler temperature difference.Reset Type 3 adds ± 30° F (± 16° C) based on the temperaturedifference between the entering and leaving chilled watertemperature.To configure Reset Type 3, enter the chilled water tempera-ture difference (the difference between entering and leavingchilled water) at which no temperature reset occurs (CHWDELTA T –> NO RESET). This chilled water temperature dif-ference is usually the full design load temperature difference.Next, enter the difference in chilled water temperature at whichthe full amount of reset occurs (CHW DELTA T –> FULL RE-SET). Finally, enter the amount of reset (DEGREES RESET).Reset Type 3 can now be activated.Demand Limit Control Option — The demand limitcontrol option (20 mA DEMAND LIMIT OPT) is externallycontrolled by a 4 to 20 mA or 1 to 5 vdc signal from an energymanagement system (EMS). The option is set up on theRAMP_DEM screen. When enabled, 4 mA is the 100% de-mand set point with an operator-configured minimum demandat a 20 mA set point (DEMAND LIMIT AT 20 mA).The auto. demand limit is hardwired to terminals J5-1 (–)and J5-2 (+) on the CCM. Switch setting number 1 on SW2will determine the type of input signal. With the switch set atthe ON position the input is configured for an externally pow-ered 4 to 20 mA signal. With the switch in the OFF position theinput is configured for an external 1 to 5 vdc signal.Surge Prevention Algorithm (Fixed SpeedChiller) — This is an operator-configurable feature that candetermine if lift conditions are too high for the compressor andthen take corrective action. Lift is defined as the difference be-tween the pressure at the impeller eye and at the impellerdischarge. The maximum lift a particular impeller wheel canperform varies with the gas flow across the impeller and thesize of the wheel.A surge condition occurs when the lift becomes so high thegas flow across the impeller reverses. This condition can even-tually cause chiller damage. The surge prevention algorithmnotifies the operator that chiller operating conditions are mar-ginal and to take action to help prevent chiller damage such aslowering entering condenser water temperature.The surge prevention algorithm first determines if correc-tive action is necessary. The algorithm checks 2 sets of opera-tor-configured data points, the minimum load points (MIN.LOAD POINT [T1,P1]) and the full load points (FULL LOADPOINT [T2,P2]). These points have default settings as definedon the OPTIONS screen or on Table 4.The surge prevention algorithm function and settings aregraphically displayed in Fig. 21 and 22. The two sets of loadpoints on the graph (default settings are shown) describe a linethe algorithm uses to determine the maximum lift of the com-pressor. When the actual differential pressure between the cool-er and condenser and the temperature difference between theentering and leaving chilled water are above the line on thegraph (as defined by the minimum and full load points), the al-gorithm goes into a corrective action mode. If the actual valuesare below the line and outside of the deadband region, the algo-rithm takes no action. When the point defined by the ACTIVEDELTA P and ACTIVE DELTA T, moves from the regionwhere the HOT GAS BYPASS/SURGE PREVENTION is off,the point must pass through the deadband region to the linedetermined by the configured values before the HOT GASBYPASS/SURGE PREVENTION will be turned on. As thepoint moves from the region where the HOT GAS BYPASS/SURGE PREVENTION is on, the point must pass through thedeadband region before the HOT GAS BYPASS/SURGEPREVENTION is turned off. Information on modifying the de-fault set points of the minimum and full load points may befound in the Input Service Configurations section, page 55.The state of the surge/hot gas bypass algorithm on theHEAT_EX DISPLAY SCREEN (Surge/HGBP Active?).Corrective action can be taken by making one of 2 choices.If a hot gas bypass line is present and the hot gas option isselected on the OPTIONS table (SURGE LIMIT/HGBPOPTION is set to 1), the hot gas bypass valve can be energized.If the hot gas bypass option is not selected (SURGE LIMIT/HGBP OPTION is set to 0), hold the guide vanes. See Table 4,LEGEND∆P = (Condenser Psi) – (Cooler Psi)∆T = (ECW) – (LCW)Fig. 21 — 19XR Hot Gas Bypass/SurgePrevention with Default English SettingsECW — Entering Chilled WaterHGBP — Hot Gas BypassLCW — Leaving Chilled WaterLEGEND∆P = (Condenser kPa) – (Cooler kPa)∆T = (ECW) – (LCW)Fig. 22 — 19XR Hot Gas Bypass/SurgePrevention with Default Metric SettingsECW — Entering Chilled WaterHGBP — Hot Gas BypassLCW — Leaving Chilled Water