Trane RT-PRC031-EN Electrical Data, Electrical Service Sizing, Set 2. Cooling with Electric Heat

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Electrical Data

Electrical Service Sizing

To correctly size electrical service wiring for a unit, find the appropriate calculations listed below. Each type of unit has its own set of calculations for MCA (Minimum Circuit Ampacity), MOP (Maximum Overcurrent Protection), and RDE (Recommended Dual Element fuse size). Read the load definitions that follow and then find the appropriate set of calculations based on unit type.

Note: Set 1 is for cooling only and cooling with gas heat units, and set 2 is for cooling with electric heat units.

Load Definitions: (To determine load values, see the Electrical Service Sizing Data Tables on the following page.)

LOAD1 = CURRENT OF THE LARGEST MOTOR

LOAD2 = SUM OF THE CURRENTS OF ALL REMAINING MOTORS

LOAD3 = CURRENT OF ELECTRIC HEATERS

LOAD4 = ANY OTHER LOAD RATED AT 1 AMP OR MORE

Set 1. Cooling with Gas Heat Air Handling Units

MCA = (1.25 x LOAD1) + LOAD2 + LOAD4

MOP = (2.25 x LOAD1) + LOAD2 + LOAD4

Select a fuse rating equal to the MOP value. If the MOP value does not equal a standard fuse size as listed in NEC 240-6, select the next lower standard fuse rating.

Note: If selected MOP is less than the MCA, then select the lowest standard maximum fuse size which is equal to or larger than the MCA, provided the selected fuse size does not exceed 800 amps.

RDE = (1.5 x LOAD1) + LOAD2 + LOAD4

Select a fuse rating equal to the RDE value. If the RDE value does not

equal a standard fuse size as listed in NEC 240-6, select the next higher standard fuse rating.

Note: If the selected RDE is greater than the selected MOP value, then select the RDE value to equal the MOP value.

Set 2. Cooling with Electric Heat

To arrive at the correct MCA, MOP, and RDE values for these units, two sets of calculations must be performed. First calculate the MCA, MOP, and RDE values as if the unit was in cooling mode (use the equations given in Set 1). Then calculate the MCA, MOP, and RDE values as if the unit were in the heating mode as follows.

MCA = 1.25 x (LOAD1 + LOAD2 + LOAD4) + LOAD3

The nameplate MCA value will be the larger of the cooling mode MCA value or the heating mode MCA value calculated above.

MOP = (2.25 x LOAD1) + LOAD2 + LOAD3 + LOAD4

The selection MOP value will be the larger of the cooling mode MOP value or the heating mode MOP value calculated above.

Select a fuse rating equal to the MOP value. If the MOP value does not equal a standard fuse size as listed in NEC 240-6, select the next lower standard fuse rating.

Note: If selected MOP is less than the MCA, then select the lowest standard maximum fuse size which is equal to or larger than the MCA, provided the selected fuse size does not exceed 800 amps.

RDE = (1.5 x LOAD1) + LOAD2 + LOAD3 + LOAD4

The selection RDE value will be the larger of the cooling mode RDE value or the heating mode RDE value calculated above.

Select a fuse rating equal to the RDE value. If the RDE value does not equal a standard fuse size as listed in

NEC 240-6, select the next higher standard fuse rating.

Note: If the selected RDE is greater than the selected MOP value, then select the RDE value to equal the MOP value.

GENERAL NOTE

Note: The selected MOP value is stamped in the MOP field on the nameplate.

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RT-PRC031-EN

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Contents IntelliPak II Air Handlers Introduction Table of Contents Standard Features Features and BenefitsControls Cabinet Mechanical Features and Benefits Optional Features Features and Benefits Field Installed Accessories Features SummaryInstallation and Service ReliabilityIntegrated Comfort with Trane Tracer LCI Features and Benefits Application FlexibilitySimplifying the Comfort System Interoperability Features and BenefitsOptimum Building Comfort Control Statitrac Direct Space Building Pressurization Control StatitracSupply Fans with Inlet Guide Vanes Variable Frequency Drives VFDControls Variable Air Volume VAV Only Supply Air Temperature Controls Supply Air Pressure ControlSupply Air Setpoint Reset Controls Variable Air Volume VAV OnlyHeating Zone Temperature Control Controls Constant Volume CV Only Occupied Zone Temperature ControlHeating Gas Heating Two-StageControls Constant Volume CV Only Auto Changeover Unoccupied Zone Temperature ControlCooling and Heating Hot Water or Steam HeatingControls VAV and CV Space Pressure Control StatitracMorning Warm-up Options Emergency OverrideControls VAV and CV Ventilation Override Module VOMGeneric Building Automation System Module Gbas 0-5 vdc Human Interface Panel HIHuman Interface Panel Main Menu Generic Building Automation System Module Gbas 0-10 vdc Chilled Water Coil Freeze StatSteam and Hot Water Coil Freeze Avoidance Night Setback SensorsDry Bulb Temperature Control of Economizer Occupied/Unoccupied input on the RTMTrane Tracer or BAS System Timed Override ActivationHumidification Control LonTalk Building Automation SystemReturn Fan Control TwinningApplications Considerations Exhaust/Return Fan OptionsApplication Recommendations AdvantagesSupply and Return Airflow Configurations Applications ConsiderationsSupply Airflow Configuration Return Airflow ConfigurationWith Bag CartridgeCorrosive Atmospheres Ventilation Override SequencesNatural Gas Heating Considerations Acoustical ConsiderationsUnit Placement Clearance RequirementsProtecting Hydronic Coils From Freezing Duct DesignExternal Piping Enclosure Selection Procedure Selection Procedure Exhaust Fan Motor Sizing Return Fan Motor SizingUnit Electrical Requirements Altitude CorrectionsModel Number Description Digit 7 Chilled Water Coil FIN SeriesModel Number Description Digit 20 System Control SelectionDigit 38 Belt Guards Burglar BARS/MARINE Lights General Data All dimensions in inches General DataGeneral Data Gas Heat Inputs/Input Ranges Economizer Outdoor Air Damper Leakage at rated airflowiInputs MBH Input MBH Range MBH Standard Damper Optional Low Leak DamperPerformance Adjustment Factors Wet Bulb Temperature Btu per PoundEnthalpy of Saturated Air Gas Heating Capacity Altitude Correction FactorsChilled Water Coil Capacities-2 Row 5W Performance Data-Chilled Water Coil CapacitiesDB F WB F Performance Data-Chilled Water Coil Capacities Chilled Water Coil Capacities-4 Row WChilled Water Coil Capacities-6 Row WD Chilled Water Coil Capacities-8 Row WD Supply Fan Performance Standard CFM Casing a Total Static Pressure Std Air1644 Supply Fan w/o IGV Supply Fan Performance Standard CFM -Casing B 9311117 Supply Fan Performance Standard CFM-Casing B Supply Fan Performance Standard CFM Casing C 7491019 Total Static Pressure Std AirPerformance Data Supply Fan with Inlet Guide Vanes Performance Data Supply Fan with Inlet Guide Vanes Supply Fan Performance Standard CFM-Casing a Supply Fan Performance Standard CFM Casing B 1093 1600 RPM 1500 RPM 779 1021 1283 Performance Data-Exhaust Fan Negative Static Pressure Std AirPerformance Data-Exhaust Fan Static PresureInWC237i Wocfm Exhaust Fan Performance Standard CFM-Case C 32 Fan 4150 R P M Performance Data-Return Fan Return Fan Performance Standard CFM-Case a 36.5 FanPerformance Data-Return Fan Return Fan PerformanceReturn Fan Performance Standard CFM-Case B and Case C 40 Fan Return Fan Performance Electric Heat Air Temperature Rise Performance Data-HeatNatural Gas Heating Capacities1 Electric Heat kw RangesPerformance Data-Heat Hot Water Coil Heating Capacities Q/ITDSteam Coil Heating Capacities Q/ITD Properties of SteamChilled Water Coil Airside Pressure Drop in H20 Component Static Pressure Drops in. H2OCartridge Filters Throw Temp Hi Temp Away Prefilter Casing High Low PD Cartridge Bag FiltersFilters Prefilter Supply Air Fan Drive Selections Drive NoHorse Power HP Low Casing Std Exhaust Air Fan Drive SelectionsReturn Air Fan Drive Selections 15 HP 20 HP 25 HP 30 HP 40 HP Drive NoElectrical Service Sizing Electrical DataSet 1. Cooling with Gas Heat Air Handling Units Set 2. Cooling with Electric HeatElectrical Service Sizing Data-Motors Electrical Data Voltage Utilization RangeUnit Voltage Nominal Tons Voltage 460 575 FLA Add 90-150Dimensional Data Unit Top/Front ViewUnit Dimensions In.-One-Piece Unit Dimensional DataReturn Exhaust Unit Height Fan Casing Opening Downflow/Horizontal Airflow Configuration DimensionsSupply Opening Blank Casing Gas Heat Section Electrical Entry Details Piping Chilled Water Piping Locations Minimum Required Clearance Unit Option Selection Door Swing Ft. StandardMinimum Required Clearance Ft Control Exh BoxBlank Casing Section Dimensions Blank Casing SectionCross Member Location Blank Casing Section Field Installed Sensors Variable Air Volume VAV Field Installed Sensors Constant Volume CV Field Installed Sensors VAV and CV Wireless Zone Sensor Wall or Duct Mount CO2 Zone Sensors Approximate Operating Weights Lbs WeightsComponent Weights Lbs Weights Installed Shipping Casing Blank Weight Roof Curb WeightsSize Wt lbs Control Box Main 454 Convenience Outlet Options Options FiltersFresh Air System ControlAgency Approval Miscellaneous OptionsField Installed Accessories Electronic Zone SensorsRoof Curb General Mechanical SpecificationsElectrical System Mechanical Specifications Cooling System Chilled Water Coil Water ValveExternal Piping Enclosure Air Handling SystemMechanical Specifications Filters Mechanical Specifications Exhaust AirNo Relief Standard Percent Modulating Exhaust Fan OptionMechanical Specifications Return Air Fresh AirHeating System CO2 Sensing Page RT-PRC031-EN
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