American Standard CH530 Controls Chilled Water Reset CWR, Return Water, Outdoor Air Temperature

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Machine Protection

and Adaptive

Control

Controls Chilled Water Reset (CWR)

Chilled water reset is designed for those applications where the design chilled water temperature is not required at partload. In these cases, the leaving chilled water temperature setpoint can be reset upward using the CWR features.

When the CWR function is based on return water temperature, the CWR feature is standard.

When the CWR function is based on outdoor air temperature, the CWR feature is an option requiring an outdoor temperature sensor module installed in the UCP panel, and sensor installed outdoors.

The type of CWR is selected in the Operator Interface settings Menu along with the Reset Ratio, Start Reset Setpoint, and the Maximum Reset Setpoint.

CDHF-SVU01C-EN

The following equations and parameters apply for CWR.

Return Water

CWS’ = CWS + RATIO (START RESET - TWE - TWL) and CWS’ > or = CWS and CWS’ - CWS < or =

Maximum Reset.

Outdoor Air Temperature

CWS = CWS + RATIO (START RESET

-TOD) and CWS’ > or = CWS and CWS - CWS < or = Maximum Reset.

Where

CWS’ is the new chilled water setpoint.

CWS is the active chilled water setpoint before any reset has occurred.

RESET RATIO is a user adjustable gain.

START RESET is a user adjustable reference.

TOD is the Temperature Outdoor Sensor.

TWE is entering evaporator water temperature.

TWL is the Leaving Evaporator Temperature.

MAXIMUM RESET is a user adjustable limit providing the maximum amount of reset. For all types of reset, CWS - CWS < or = Maximum Reset.

Both Return and Outdoor Reset do not apply to Heating Mode where the UCP is controlling the Leaving Condensing Hot Water Temperature.

Constant Return Reset will reset the leaving water temperature setpoint so as to provide a constant entering water temperature. The Constant Return Reset equation is the same as the Return Reset equation except on selection of Constant Return Reset, the UCP shall automatically set RATIO, START RESET, and MAXIMUM RESET to the following:

The RATIO = 100 percent

The START RESET = Design Delta Temperature

The MAXIMUM RESET = Design Delta Temperature

The equation for Constant Return is as follows:

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Contents X39640670030CDHF-SVU01C-EN Read these carefully Contents Unit Nameplate General InformationLiterature change About this manualGeneral Information = 560 3 stage 935 2 stage Y = 500 3 stage 835 2 stage Control Optional Packages Commonly Used AcronymsGeneral Duplex unit components front view OverviewGeneral Duplex unit components 2 stage compressor Compressor 1 or 2 2 Stage Cooling CyclePressure enthalpy curve 3 stage compressor Pressure enthalpy curve 2 stage compressor DynaView Human Interface TechView Chiller Service ToolTimeline Text Figures Power Up DiagramSoftware Operation Overview Diagram Software States FigureStaging Second Compressor On CDHE/F/G sequence of operation auto to runningSatisfied Setpoint Staging Second Compressor OffCDHF/G sequence of operation lead 1/lag CDHE/F/G sequence of operation lead 2 lag Fixed Sequence Compressor 2 / CompressorCDHF/G sequence of operation equalize starts and hours Sequencing Balanced Starts and HoursCDHF/G sequence of operation combined start Simultaneous Compressor Start/ StopClear Restart Inhibit Restart Inhibit Start to Start Time SettingRestart Inhibit Restart Inhibit Free StartsOil and Refrigerant Pump Surface TemperaturesOil refrigerant pump circuit 1 or 20 100 percent RLA Base Loading Control AlgorithmGeneral Information Sequence of operation ice making running to ice making Ice Machine ControlHot Water control Unit Control Panel UCP Unit Control Panel UCPControl Panel Devices and Unit Mounted Devices User-defined language support Variable water flow through the evaporatorDynaView main processor Operator InterfaceOperator Interface How It Works Chiller Stop Prevention/Inhibit FeatureTop Level Mode Description System Reset Reference Main Screen Data Fields Table Chiller Operating ModeCircuit Operating Mode Main ScreenDiagnostic Screen Back button provides navigation back to the chiller screen Operator Interface Reports Report MenuReport name Circuit Condenser Report name System EvaporatorReport name Circuit Evaporator Report name System CondenserReport name System Ashrae Chiller Log Historic Diagnostics LogHeader Screen Setting Tab screens provides a userChiller Feature SettingsPurge System Mode OverridesCircuit Mode Overrides Display SettingsOperator Interface Operator Interface Operator Interface Operator Interface Operator Interface Binding Interprocessor CommunicationInter Processor Communications IPC3 IPC3 Definitions Bus ManagementControl panel components layout Control System ComponentsControl System Components Control Panel Devices Compressor Running Relay Machine Shutdown Manual Reset MMRHead Relief Request Output Maximum Capacity RelayExop Refrigerant Monitor Input 1A17Epro Enhanced Protection Trmm TRM4 Tracer Comm 4 interfaceCdrp Condenser Refrigerant Pressure Output Pressure based Temperature basedCdrp Refrigerant Pressure Output Option 1A15 Condenser Pressure OutputRefrigerant Differential Pressure Indication Output Percent RLA Output Gbas Generic Building Automation SystemWpsr WFC Water Pressure Sensing Option Module CharacteristicsExternal Chilled Water Setpoint Ecws External Current Limit Setpoint1A14 Communication interface Module 1A8, 1A9, 1A11, 1A12 Quad Relay Output Status1A13, 1A18, 1A19, 1A20 Dual Binary input module Analog Input Recommended Length to Run external Output signals1A15, 1A16, 1A17, 1A21 Dual Analog Input/output Module Unit mounted devices Control System Components Control System Components UCP and Wye-Delta Starter Control Circuits Control Sequence of OperationElectrical Sequence Delay time 200 msec. Opens 2K1 Control Sequence of Operation Test and start timing sequence Control Sequence OperationAFD Machine Protection Adaptive Control Momentary Power Loss MPL ProtectionOverload trip time versus percent RLA Current Overload ProtectionReverse Rotation Protection Phase Loss ProtectionCurrent Limit Protection Minimum and Maximum Capacity Limit Differential to Start or StopSoftLoading Evaporator Limit Leaving Water Temperature CutoutHead Relief Relay Low Refrigerant Temperature CutoutCutout strategy Condenser Limit Restart Inhibit High Vacuum Lockout Oil Temperature Control Return Water Controls Chilled Water Reset CWROutdoor Air Temperature Maximum ResetEquation Values for start reset typesDegrees of Reset Constant ReturnOutdoor air temperature versus degrees of reset Reset RatioReset function for return CWR Reset Ratio = 50% Return CWR Daily Unit Start-Up Unit Start-Up ProceduresUnit Startup Mode Live Electrical ComponentsToxic Hazards Seasonal Unit Start-UpSeasonal Unit Shutdown Unit Shutdown ProceduresUnit Shutdown Oil Pump Heater OperationRecord Keeping Forms Periodic MaintenanceDaily Maintenance and Checks Moisture ContaminationEvery 3 Months Weekly MaintenanceNormal Chiller Operating Characteristics Hazardous Voltage w/CapacitorsAnnual Maintenance Off-Season MaintenanceCompressor Oil Change Oil MaintenanceOil Change Procedure Heater DamageReplacing Oil Filter Oil Filter ReplacementHazardous Voltage w/ Capacitors MaintenanceOil Supply System Problems Other Maintenance RequirementsFront View with Refrigerant Pump Rotary valve in drain positionRefrigerant Charge Contains RefrigerantProper Water Treatment Recovery and Recycle ConnectionsLeak Testing Cleaning the CondenserUnit Corrosion Damage Cleaning the EvaporatorControl Settings Adjustments Unit Preparation Purge System103 104 105 106 107 108 109 110 111 112 113 114 115 Trane