Carrier 48/50PD05 User Manual

15Outdoor Fan OperationThe 48/50 PD units use a multi--speed outdoor fan motor to controlthe head pressure within an acceptable range at low outdoorambient temperatures. On the 48 and 50 PD--05 and 06 size unitsthe outdoor fan contactor is powered on the load side of thecompressor contactor so the outdoor fans will run only when thecompressor contactor is energized. When the outdoor fancontactor is not energized the outdoor fan runs at high speed.When the outdoor fan contactor is energized the outdoor fan runsat low speed.The outdoor fan speed is controlled by a system three of fan levelsset up in the control software. Table 6 shows the three levels andfan speeds for each level. The fan levels are determined byOutdoor Air Temperature (Temperatures→AIR.T→OAT) but canbe overridden by Condenser Pressure A (Pressures→SCP.A)inputs to the Main Base Board.FANLEVELFANSPEEDCONDITIONS TO TRANSITION TO NEXTLOWER LEVELCONDITIONS TO TRANSITION TO NEXTHIGHER LEVEL0 OFF N/A1. Compressor Contactor is ON(on initial start up outdoor fan runs at Level 2 for10 seconds before moving to correct level basedon outside air temperature or Condenser Pres-sure A)1 LOW 1. Compressor Contactor is OFF1. Outside Air Temperature Control — FanLev2 On Temperature 55 F or above (Configu-ration→COOL→OFC→2.ON >=55F)*2. Condenser Pressure A Override — FanLev1 Max Pressure 450 psig or above (Config-uration→COOL→OFC→1.MXP>= 450 psig)*2 HIGH1. Outside Air Temperature Control --- --- FanLev2 Off Temperature 45 F or below (Confi-guration→COOL→OFC→2.OFF <=45F)*2. Condenser Pressure A Override --- --- FanLev2 Min Pressure 200 psig or below (Config-uration→COOL→OFC→2.MNP<= 200 psig)*N/ATable 6 — Fan Level Control of Outdoor Fan*Configuration parameters 1.MXP, 2.MNP, 2.ON and 2.OFF factory default configuration should not be changed. The default configurations have been qualified over a widerange of conditions and are provided in case a field replacement of the control board occurs and the settings need to be checked or manually configured.\Economizer OperationIf an economizer is installed, then Economizer Installed(Configuration→UNIT→EC.EN) should be set to YES. Theeconomizer is controlled by the Econo Commanded Position(Outputs→ECON→EC.CP) on the Economizer Control Board(ECB). Feed back from the economizer actuator is output onconfiguration parameter Econo Actual Position(Outputs→ECON→EC.AP).Economizer Actuator CommunicationThe economizer actuator used with the 48/50PD units is aMulti--Function Technology (MFT) actuator. This allows theComfortLink system to communicate with the actuator through afeedback signal. The configuration Economizer Control Type(Configuration→ECON→E.CTL) determines the communicationmethod, either digital or analog, used to communicate between theEconomizer Control Board and the economizer actuator.The power to the unit must be cycled after the Economizer ControlType (Configuration →ECON→E.CTL) configuration parameteris changed.E.CTL = 1 or 2 (Digital/Position or Digital/Command)When Economizer Control Type(Configuration→ECON→E.CTL) is set to 1, the EconomizerControl Board will communicate with the economizer actuatorusing the digital protocol, from Economizer Control Board plugJ7--1 to actuator pin 5. The commanded position and the actuatorsactual position are communicated back and forth between theactuator and the Economizer Control Board. When the EconomizerControl Board and actuator first initiate communication, a ControlAngle Economizer Control Type (Operating Modes→ECON→C.ANG) is provided to the Economizer Control Boardand defines the actuator’s range of motion. The control angle mustbe greater than the Min Actuator Ctrl Angle(Configuration→ECON→M.ANG). During this digital control,the Economizer Control Board analog 4 to 20 mA output willrepresent the actuator’s actual position when E.CTL = 1 orcommanded position when E.CTL = 2. Because the wiring has abuilt--in 500--ohm resistor, the 4 to 20mA signal is converted to a 2to 10VDC signal that is accessible via a field connected terminalboard TB--8 and TB--9. However, before this signal can be readremotely, the violet wire that connects the actuator to fieldconnection terminal board TB--J10--8 must be removed or cut.E.CTL = 3 (Analog Control)When E.CTL is set to 3, the Economizer Control Board will NOTcommunicate with the economizer actuator directly with the 4 to20mA analog signal wired to TB--8 and TB--9 along with the500--ohm resistor producing a 2 to 10VDC signal for the actuator.While in this mode, the actuator’s built--in 2 to 10VDC feedbacksignal s accessible via TB--9 and TB--10 any time because it is notused by the Economizer Control Board.Free CoolingThe economizer will be allowed to help with cooling if theOutdoor Air Temperature (Temperatures→AIR.T→OAT) is lessthan the configured Econo Cool Hi Temp Limit(Configuration→ECON→EH.LO) and greater than theconfigured Econo Cool Lo Temp Limit(Configuration→ECON→EL.LO). If an enthalpy sensor isinstalled, the outdoor temperature must be below the Econo CoolHi Temp Limit (Configuration→ECON→EH.LO) and theOutdoor Enthalpy Switch (Inputs→GEN.I→ENTH) must beLOW.Unoccupied Free CoolingThe unoccupied free cooling algorithm attempts to maintain thebuilding space half way between the Occupied Cool Set Point(Setpoints→OCSP) and Occupied Heat Set Point(Setpoints→OHSP) using only the economizer when theconditions in the building and the outdoors are suitable., duringUNoccupied periods if the air in the building and the outdoor airare suitable. Three different configurations define this algorithm:1. Unoccupied Free Cooling(Configuration→ECON→UEFC)48/50PD