Carrier AQUASNAP 30RAP010-150 Controls, Start-up, Operation, Service, And Troubleshooting

Also see for AQUASNAP 30RAP010-150: Start up & operation manual Installation instructions Installation instructions Controls, start-up, operation, service, and troubleshooting

Carrier AQUASNAP 30RAP010-150 Controls, Start-up, Operation, Service, And Troubleshooting Manual pdf 48 page image

482. Determine maximum deviation from average voltage:(AB) 243 – 239 = 4 v(BC) 239 – 236 = 3 v(AC) 239 – 238 = 1 vMaximum deviation is 4 v.3. Determine percent voltage imbalance:This voltage imbalance is satisfactory as it is below themaximum allowable of 2%.Control Circuit Power — Power for the control circuit issupplied from the main incoming power through a factory-installed control power transformer (TRAN1) for all models.Field wiring connections are made to the LVT.OPERATION SEQUENCEDuring unit off cycle, the control monitors the outdoor airtemperature. If the ambient temperature drops below 40 F(4.4 C), cooler and hydronic system heaters (if either are facto-ry installed) are energized. If power is maintained to the chillerand the EMERGENCY ON/OFF switch is left in the OFF po-sition, these heaters are also energized.The unit is started by putting the ENABLE/OFF/REMOTECONTACT switch in the ENABLE or REMOTE CONTACTposition. When the unit receives a call for cooling (either fromthe internal control or CCN network command or remote con-tact closure), the unit stages up in capacity to maintain the leav-ing fluid set point. The first compressor starts 11/2 to 3 minutesafter the call for cooling.The lead circuit can be specifically designated on all modelsor selected based on compressor run hours and starts depend-ing on field configuration. The unit control will override thisselection under certain starting conditions to properly maintainoil return to the compressors. In general, on dual compressorcircuits, the control will most often start the A1 or B1 compres-sor first, especially after long off periods. The MBB controlsfan stages to maintain the head pressure set point and will auto-matically adjust unit capacity as required to keep compressorsfrom operating outside of the specified envelope. There are nopumpout or pumpdown sequences on these chillers.For all units, if temperature reset is being used, the unit con-trols to a higher leaving-fluid temperature as the building loadreduces. If demand limit is used, the unit may temporarily beunable to maintain the desired leaving-fluid temperature be-cause of imposed power limitations.SERVICEElectronic ComponentsCONTROL COMPONENTS — Unit uses an advanced elec-tronic control system that normally does not require service.Access to the compressors is through latched panels frombeneath the control box on all models or from opposite the coilside (sizes 010-030 only). The front door(s) provide access tothe compressor(s) and all components of the refrigerationsystem. For size 010-030 units, access to the controls is throughthe upper latched outer door above the compressor access door.Similarly, the upper center latched door on sizes 035-150 givesaccess to the controls. Inner panels are secured in place andshould not be removed unless all power to the chiller is off.Electronic Expansion Valve (EXV) — See Fig. 30for a cutaway view of the EXV. High-pressure liquid refriger-ant enters valve through the top. As refrigerant passes throughthe orifice, pressure drops and refrigerant changes to a 2-phasecondition (liquid and vapor). The electronic expansion valveoperates through an electronically controlled activation of astepper motor. The stepper motor stays in position, unlesspower pulses initiate the two discrete sets of motor stator wind-ings for rotation in either direction. The direction depends onthe phase relationship of the power pulses.As the stepper motor rotates, its motion is transferred to lin-ear movement by a lead screw. Refrigerant flow is modulatedby either opening or closing the port. The valve includes a pos-itive shut-off when closed.% Voltage Imbalance = 100 x 4239= 1.7%IMPORTANT: If the supply voltage phase imbalance ismore than 2%, contact your local electric utility companyimmediately. Do not operate unit until imbalance conditionis corrected.WARNINGElectrical shock can cause personal injury and death. Shutoff all power to this equipment during service. There maybe more than one disconnect switch. Tag all disconnectlocations to alert others not to restore power until work iscompleted.1. Cable2. Glass Seal3. Motor Housing4. Stepper Motor5. Bearing6. Lead Screw7. Insert8. Valve Piston9. Valve Seat10. Valve PortFig. 30 — Cutaway View of the ElectronicExpansion Valve (Size 070-150 Shown)