Carrier AquaSnap 30MPA Series Controls, Start-up, Operation, Service, And Troubleshooting

Also see for AQUASNAP 30MPA: User manual Operation and service manual Installation instructions

Carrier AquaSnap 30MPA Series Controls, Start-up, Operation, Service, And Troubleshooting Manual pdf 36 page image

36Digital Scroll Option — The 30MP020-045 units havea factory-installed option for a digital scroll compressor whichprovides additional stages of unloading for the unit. The digitalcompressor is always installed in the A1 compressor location.When a digital compressor is installed, a digital unloader sole-noid (DUS) is used on the digital compressor. Digital ScrollOption not available for units controlled by the Multi-Chiller Controller Accessory panel.DIGITAL SCROLL OPERATION — A digital scroll oper-ates in two stages — the “loaded state” when the solenoidvalve is de-energized and the “unloaded state” when the sole-noid valve is energized. During the loaded state, the compres-sor operates like a standard scroll and delivers full capacity andmass flow.However, during the unloaded state, there is no capacityand no mass flow through the compressor. The capacity of thesystem is varied by varying the time the compressor operatesin an unloaded and loaded state during a 15-second period. Ifthe DUS is energized for 7 seconds, the compressor will beoperating at 47% capacity. If the DUS is energized for 10 sec-onds, the compressor will be operating at approximately 33%of its capacity. Capacity is the time averaged summation ofloaded and unloaded states, and its range is continuous fromthe minimum configured capacity to 100%. Regardless ofcapacity, the compressor always rotates with constant speed.As the compressor transitions from a loaded to unloaded state,the discharge and suction pressures will fluctuate and the com-pressor sound will change.The ComfortLink controller controls and integrates the op-eration of the DUS into the compressor staging routine tomaintain temperature control. When a digital compressor is in-stalled, an additional discharge gas temperature thermistor(DTT) is installed along with the AUX board for control of theDUS.DIGITAL COMPRESSOR CONFIGURATION — When adigital compressor is installed, the configuration parameter(ConfigurationUNITA1.TY) is configured to YES.There is also a maximum unload time configuration, (Config-urationUNITMAX.T) that is set to 10 seconds (sizes020,030) or 7 seconds (sizes 040,045), which indicates themaximum unloading for the digital compressor is 47%. This isdone to optimize efficiency of the system.MINIMUM LOAD CONTROL — Minimum load control isgenerally not recommended for split systems. If installed, thefeature must be enabled in the controls. Minimum load controlor hot gas bypass cannot be used in conjunction with the digitalscroll option.Minimum load control can only be added to standard com-pressor units in the field. This feature will not operate with anoptional digital compressor and when the digital function is en-abled (ConfigurationUnitA1.TY=YES). To enable theminimum load valve, confirm that the digital compressor op-tion is disabled and set Minimum Load Valve Select to YES,(ConfigurationOPT1MLV.S=YES). See Table 32.NOTE: Minimum Load Control and Digital Compressor oper-ation cannot be used together.Table 32 — Configuring Minimum Load ControlIf equipped and enabled, the Minimum Load Control valveis active as the last stage of capacity when the unit is unloading.MAINTENANCE REMINDER — The 30MP ComfortLinkcontrols have the ability to provide a reminder for service per-sonnel that regularly scheduled strainer maintenance is re-quired. Maintenance interval is a field-configurable item. Theservice interval should be adjusted for the job site conditions.See Table 33.Table 33 — Configuring Maintenance ReminderPRE-START-UPDo not attempt to start the chiller until following checkshave been completed.System Check1. Check all auxiliary components, such as chilled fluidpumps, air-handling equipment, condenser pump or otherequipment to which the chiller supplies liquid. Consultmanufacturer’s instructions. Verify that any pump inter-lock contacts have been properly installed. If the unit hasfield-installed accessories, be sure all are properly in-stalled and wired correctly. Refer to unit wiring diagrams.2. Use the scrolling marquee display to adjust the CoolingSet Point.3. Fill chilled fluid circuit with clean water (with recom-mended inhibitor added) or other non-corrosive fluid tobe cooled. Bleed all air out of the high points of the sys-tem. If chilled water is to be maintained at a temperaturebelow 40 F (4.4 C), a brine of sufficient concentrationmust be used to prevent freeze-up at anticipated suctiontemperatures. To ensure sufficient loop volume, seeTables 34 and 35.4. Check tightness of all electrical connections.5. Oil should be visible in the compressor sight glass(es).See Fig. 25. An acceptable oil level in the compressors isfrom 1/8 to 3/8 of sight glass when the compressors are off.Adjust the oil level as required. See Oil Charge section onpage 45 for Carrier approved oils.6. Crankcase heaters must be firmly attached to compres-sors, and must be on for 24 hours prior to start-up(30MPA015-045, 30MPA,MPW050-071 only).7. Electrical power source must agree with unit nameplate.8. Check rotation of scroll compressors. Monitor controlalarms during first compressor start-up for reverse rota-tion protection alarm.CONFIGURATIONUNITITEM EXPANSION COMMENTSA1.TY Compressor A1Digital?Range: NO/YESDefault: Depends on prod-uct configurationNO = Not EquippedValue must be set to NOCONFIGURATIONOPT1MLV.S Minimum Load VlvSelectRange: NO/YESDefault: NOSet to YES to activateRUN STATUSPMSTRNITEM EXPANSION COMMENTSSI.ST Strainer Srvc IntervalRange: 0 to 65,500 hrsDefault: 8760 hrsSetting SI.ST to 0 disablesthe featureIMPORTANT: Before beginning Pre-Start-Up or Start-Up,complete Start-Up Checklist for 30MP Liquid Chiller atend of this publication (pages CL-1 to CL-8). The checklistassures proper start-up of a unit, and provides a record ofunit condition, application requirements, system informa-tion, and operation at initial start-up.