Daikin Pathfinder AWV Series Installation, Operation And Maintenance Manual

Daikin Pathfinder AWV Series Installation, Operation And Maintenance Manual Manual pdf 58 page image

IOM 1242-2 • PATHFINDER® MODEL AWV CHILLERS 58 www.DaikinApplied.comCIrCuIT funCTIonsCIrCuIT funCTIonsCircuit FunctionsComponents controlled at the circuit level include:• Compressor VFD• Compressor VR Solenoid Valves• Evaporator EXV• Economizer EXV• Liquid Line Solenoid Valve• Liquid Injection Solenoid Valve• Condenser FansCalculationsCalculations are for each circuit.Approach ValuesEvaporator Approach = LWT – Evap Saturated TempCondenser Approach = Cond Saturated Temp – OATSuperheat ValuesSuction superheat = Suction Temp – Evap Saturated TempDischarge superheat = Discharge Temp – Cond SaturatedTempEconomizer Superheat = Econ Temp – Econ Saturated TempDifferential Pressure ValuesOil Pressure Differential = Cond Pressure - Oil PressurePressure Difference = Cond Pressure – Evap PressurePressure RatioPressure Ratio = (Cond Press +101.325) ÷ (Evap Press +101.325)Feedback CapacityFeedback capacity is a representation of the actual capacity asa percentage of full capacity based on feedback regarding theactual speed of the compressor.Compressors vary capacity via changes to the speed. Theactual compressor speed is read from the VFD. Feedbackcapacity for a compressor with a VFD is:Actual Compressor Speed x 100 ÷ Maximum SpeedSaturated Condenser Temperature LimitThe maximum saturated condenser temperature calculationis based on the compressor operational envelope. This valueis used for triggering high condenser pressure alarms and asa reference for the trigger values of the high pressure holdand unload events. Chiller software is designed to calculatea dynamic maximum saturated condenser temperature.High saturated condenser hold and unload offset values aredescribed as follows.Table 46: Saturated Condenser Temperature ConditionsCondition Saturated EvapTemp or LWTMax Cond SaturatedTemp (°C)EXV state is StartPressure ControlLWT ≤ 0°C 1.589 X LWT + 68.3LWT > 0°C 68.3EXV state is SSHor MOP ControlTe ≤ 0°C 1.589 X Te + 68.3Te > 0°C 68.3All other conditions n/a 68.3High Saturated Condenser – Hold ValueHigh Cond Hold Value = Max Saturated Cond Value – HighCond Press Hold Offset set pointHigh Saturated Condenser – Unload ValueHigh Cond Unload Value = Max Saturated Cond Value – HighCond Press Unload Offset set pointHigh Motor Current LimitsMax Motor Current = Minimum of (VFD Rated Current, MotorRated Current)where:- VFD Rated Current is read from the compressor VFD- Motor Rated Current is determined by the compressor typeand the voltage configuration:Motor Rated Current (Amps)CompressorType 380V 400V 460V 575VF3ALVVR60 222.8 222.8 183.3 167.0F3ALVVR86 375.6 375.6 311 253.5F3BLVVR86 527.9 527.9 434.1 N/AF4ALVVR80 692.1 692.1 574.8 N/APumpdown Target ValueThe pressure target for pumpdown when the circuit enters thepumpdown state is selected as follows:If Service Pumpdown set point = DisableThen Pumpdown Target = Evaporator Pressure atpumpdown start – 20 kPa with value limited to the rangefrom 35 kPa to the Pumpdown Pressure Max set pointIf Service Pumpdown set point = EnableThen Pumpdown Target = 35 kPa