Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions

Also see for WeatherExpert 48N2: Installation instructions Installation instructions Controls, start-up, operation, service, and troubleshooting Installation instructions

Contents

Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions Manual pdf 149 page image

149Table 107 — VFD Terminal DesignationsRETURN FAN — The return fan power exhaust assemblyconsists of one belt-drive plenum fan. The return fan is a belt-driven backward-curved fan. The plenum fan pressurizes theplenum fan section so that the air can either be discharged hori-zontally out the back of the unit or discharged through the re-turn air section of the economizer.ECONOMIZER MOTOR(S) — The economizer outside airand return air dampers are motor actuator-driven through link-ages. Communicating economizer motors controls their posi-tion. The motor position is controlled by the MBB through thecommunication bus. This allows for accurate control of themotors as well as feedback information and diagnostics infor-mation. The control has a self-calibration routine that allowsthe motor position to be configured at initial unit start-up. Themotors are located on the economizer and can be reachedthrough the filter access door.THERMISTORS AND PRESSURE TRANSDUCERS —The unit is equipped with several thermistors for measurementof temperatures. The thermistors are summarized in Table 108.The units have two pressure transducers that are connectedto the low side of the system. These two pressure transducersmeasure the low side pressure and are used for low pressureprotection and coil freeze protection.The units also have two pressure transducers that are con-nected to the high side of the system. These two pressure trans-ducers measure the discharge pressure and are used to cycle thecondenser fans to maintain head pressure.By using the high and low side pressure transducers, theComfortLink controls display the high and low side pressuresand saturation temperatures and a normal gage set is notrequired.SMOKE DETECTOR — The units can be equipped with anaccessory smoke detector located in the supply or return air.The detector is wired to the ComfortLink controls and, if acti-vated, will stop the unit by means of a special fire mode. Thesmoke detector can also be wired to an external alarm systemthrough TB201 terminals 1 and 2. The sensor is located in thesupply or return air sections.FILTER STATUS SWITCH — The units can be equippedwith optional accessory filter status switch on both the returnand supply (post) air filters. The switch measures the pressuredrop across the filters and closes when an adjustable pressureset point is exceeded. The sensors are located in the controlpanel. The return filter switch is connected to terminals 1 and 2on TB203. The 180-ohm resistor is on the terminals for whenthe filter pressure is used. The resistor must be removed for theswitch to operate properly. The supply filter switch is connect-ed to terminals 3 and 4 on TB203. The 180-ohm resistor mustbe removed.FILTER PRESSURE SENSOR — The units can be equippedwith optional accessory filter pressure sensors on both the re-turn and supply (post) air filters. The sensor measures the pres-sure drop across the filters and outputs a 4 to 20 mA signal thatis read by the ComfortLink controls. The sensors are located inthe control panel. The return filter sensor is connected to termi-nals 1 and 2 on TB203. The supply filter sensor is connectedto terminals 3 and 4 on TB203. The 180-ohm resistor is on theterminals for when the filter pressure sensors are used. The re-sistors must remain for the sensors to operate properly.NOTE: ComfortLink controls can accept either the filter statusswitch OR the filter pressure sensor. It cannot accept both atthe same time.FAN STATUS SWITCH — The units can be equipped withan optional fan status switch that will monitor the pressure riseacross the indoor fans.RETURN AIR CO 2 SENSOR — The unit can be equippedwith a return air IAQ CO2 sensor that is used for the demandcontrolled ventilation. The sensor is located in the return airsection and can be accessed from the filter access door.BOARD ADDRESSES — Each board in the system has anaddress. The MBB has a default address of 1 but it does havean instance jumper that should be set to 1 as shown in Fig. 34.For the other boards in the system there is a 4-dip switch head-er on each board that should be set as shown below.0 = On; 1 = OffAccessory Control Components — In addition tothe factory-installed options, the units can also be equippedwith several field-installed accessories that expand the controlfeatures of the unit. The following hardware components canbe used as accessories.ROOM THERMOSTATS — The ComfortLink controls sup-port a conventional electro-mechanical or electronic thermostatthat uses the Y1, Y2, W1, W2, and G signals. The control alsosupports an additional input for an occupied/unoccupied com-mand that is available on some thermostats. The ComfortLinkcontrols can be configured to run with up to 6 stages of capaci-ty. The room thermostat is connected to TB201.The ComfortLink controls also support the use of spacetemperature sensors and can be used with the T55 and T56 sen-sors. The controls can also be used with CCN communicatingT58 room sensor. The T55 and T56 sensors are connected toTB201 terminals 1, 2, and 3. The T58 sensor is connected tothe CCN connections on COMM board. Whenever a unitequipped with heat is operated without a thermostat, the usermust install the red jumpers from R to W1, and W2 on TB201for the heat function to work correctly.TERMINAL FUNCTIONU1 Three-phase main circuit input power supplyV1W1U2 Three-Phase AC Output to Motor, 0 V toMaximum Input Voltage LevelV2W2X1-11 (GND) Factory-supplied jumperX1-12 (D-COM)X1-10 (+24 V) Factory-supplied jumperX1-13 (DI-1)X1-10 (+24 V) Start Enable 1 (Factory-supplied jumper).When opened the drive goes to emergencystop.X1-16 (DI-4)X1-28 (SCR) Factory wired for local equipment network LENcommunicationX1-29 (B+)X1-30 (B-)X1-31 (AGND)X1-32 (SCR)BOARD SW1 SW2 SW3 SW4RXB 0 0 0 0EXB 1 0 0 0SCB 0 0 0 0CEM 0 0 0 0EXV-A 1 0 0 0EXV-B 0 1 0 0EXV-C 0 0 0 0