Carrier GEMINI 38APD025-100 Operating And Service Manual

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482. Fan status switch input should close. Note the unit willnot start unless the fan status input is closed.3. Close Y1 input unit will stage up to 50 % capacity with1 minute between stages.4. Close Y2 input the unit will stage up to 100% capacitywith 1 minute between stages.CV APPLICATION — C.TYP = 31. Start indoor fan motor.2. Fan status switch input should close. Note the unit willnot start unless the fan status input is closed.3. Close Y1 input unit. The control will control supply-airtemperature to CSP1 and stage capacity as required.4. Close Y2 input. The unit will control supply-air tempera-ture to CSP2 and stage capacity as required.CV APPLICATION — C.TYP = 51. Start indoor fan motor.2. Fan status switch input should close. Note the unit willnot start unless the fan status input is closed.3. The control will use space temperature (TemperaturesSPT) vs space temperature set point (Set PointCOOL SPS.P) to decide to whether to control supply-air temperature to CSP1 or CSP2, and will stage capacityas required.% CAPACITY INPUT — C.TYP = 71. Start indoor fan motor.2. Fan status switch input should close. Note the unit willnot start unless the fan status input is closed.3. The control will adjust unit capacity based on the 4 to20mA Cool mA (INPUTS 4-20 CL.MA).4. Actual capacity and desired capacity may be different dueto unit diagnostics.OPERATIONOperating LimitationsAMBIENT LMITATIONS — See Table 16 for ambientlimitations.Table 16 — 38AP Unit Ambient LimitationsSingle CircuitDual Circuit* Factory-installed option or field-installed accessory.†Operation above listed temperature depends on the saturated suction tem-perature the unit is operating at. Refer to ECAT for exact limitations.VOLTAGE (ALL UNITS)Main Power Supply — Minimum and maximum acceptablesupply voltages are listed in the Installation Instructions.Unbalanced 3-Phase Supply Voltage — Never operate a motorwhere a phase imbalance between phases is greater than 2%.To determine percent voltage imbalance:The maximum voltage deviation is the largest differencebetween a voltage measurement across 2 legs and the averageacross all 3 legs.Example: Supply voltage is 240-3-60.AB = 243 vBC = 236 vAC = 238 v1. Determine average voltage:2. 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 LVT terminal board.Operation Sequence — During unit off cycle, if poweris maintained to the unit and the EMERGENCY ON/OFFswitch is left in the OFF position, the compressor crankcaseheaters will be energized.The unit is started by putting the ENABLE/OFF/REMOTECONTACT switch in the ENABLE or REMOTE CONTACTposition. When the unit receives a call to run (either from theinternal control, or CCN network command or remote contactclosure), the unit stages up in capacity to maintain either supplyair temperature or space temperature. The first compressorstarts 11/2 to 3 minutes after 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. The MBB controls fan stages tomaintain the head pressure set point and will automatically ad-just unit capacity as required to keep compressors from operat-ing outside of the specified envelope. There are no pumpout orpumpdown sequences on these units.The liquid line solenoid valve is energized anytime a com-pressor is operating in the circuit and also when the circuit isOFF and the OAT is less than the SST. The liquid line solenoidvalve is de-energized 5 seconds after the circuit stops and alsowhen the circuit is OFF and the OAT is greater than the SSTplus 2° F. Each circuit operates independently.38APSUNITSIZEMINIMUM LOWAMBIENT(Standard Unit)MINIMUM LOW AMBIENTMOTORMASTER ®CONTROL*MAXIMUMAMBIENT†025-050 45 F (7.2 C) 20 F ( 28.9 C) 122 F (50 C)38APDUNITSIZEMINIMUM LOWAMBIENT(Standard Unit)MINIMUM LOW AMBIENTMOTORMASTERCONTROL*MAXIMUMAMBIENT†025-040 32 F (0 C) 20 F ( 28.9 C) 122 F (50 C)050-060 25 F ( 3.9 C) 20 F ( 28.9 C) 122 F (50 C)070-100 32 F (0 C) 20 F( 28.9 C) 122 F (50 C)% Voltage Imbalance = 100 xmax voltage deviationfrom avg voltageaverage voltage  – –– –– – –– –Average voltage = 243 + 236 + 2383= 7173= 239% 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.