Carrier PC 111 Operating And Troubleshooting Manual

Also see for 48FK034: Controls operation and troubleshooting

21EXTERNAL ALARM SIGNAL — The unit controls providean external alarm status signal via a 115-vac output signal atthe relay board J5, available at TB2-4 and TB2-5 (common).This signal can be forwarded to the BMS by adding a signalrelay at the alarm output, placing its coil across terminals TB2-4 and TB2-5 and using its contacts to control a discrete input tothe BMS (see Fig. 31).The alarm signal output is energized when any of the diag-nostic codes is tripped.REMOTE ECONOMIZER CONTROL — Economizer con-trol is tightly integrated into the unit’s capacity control algo-rithms and diagnostic routines. Consequently, controlmodifications that interfere with this standard operatingsequence are not recommended.Economizer position is determined by the unit processorboard based on current outdoor air enthalpy status and coolingcapacity demand. The economizer damper actuator is a floatingpoint device with an internal brake and spring return. Its posi-tion is determined by the sequencing of relays EOR (Econo-mizer Open Relay) and ECR (Economizer Close Relay). Theeconomizer’s current position is sensed by the processor boardthrough position feedback potentiometer P2.Whenever the economizer position potentiometer signal isnot consistent with the processor board’s commanded position,a fault condition is determined by the processor board and analarm signal is initiated. The processor board also attempts toreturn the economizer damper to its fully closed position dur-ing this fault condition by energizing the ECR relay.Any attempt to effect an external control of the economizeractuator will lead to an alarm condition and an automatic re-sponse by the unit control to attempt to close the dampers.Smoke Control Modes — It is common practice to userooftop units for aid in building smoke control in the event of abuilding fire. The available functions include: Fire Shutdown,Pressurization, Evacuation, and Smoke Purge. These functionsare enhanced when multiple rooftop units are used to zone abuilding.Implementation of the various Smoke Control modes onthese units requires the installer to modify the unit wiring toadd contacts (via either manual switches or relays) that will se-lectively interrupt and override standard factory control se-quences. See Table 5.Smoke control mode Pressurization requires the economiz-er function. Evacuation and Smoke Purge modes require botheconomizer and power exhaust functions. Both functions arestandard features on 48FM and 50FM,FS units. These func-tions require factory-installed options, field-installed accesso-ries and/or field-supplied exhaust systems on 48FK,JK and50FK,FY,JK,JY units. Consult price pages for specific details.FIRE SHUTDOWN MODE — Fire Shutdown mode termi-nates all unit operation (cooling, heating, supply fan and powerexhaust). This mode prevents recirculation of contaminated airback into the space or the admission into the space of unsuit-able outside air.PRESSURIZATION MODE — Pressurization mode isintended to keep smoke out of a zone. The economizer isrequired for this function. The economizer is standard on48FM and 50FM,FS units. The economizer is a factory-installed option on 48FK,JK and 50FK,FY,JK,JY units. Pres-surization is accomplished by:• opening the economizer• running the supply fan (optional inlet guide vanes openor optional VFD [variable frequency drive] at normalduct static pressure set point)• shutting off the power exhaust fans (Standard on 48FMand 50FM,FS units. Factory-installed option or field-installed accessory on 48FK,JK and 50FK,JK units)This allows the space to be overpressurized relative to adja-cent zones and prevents or slows entry of smoke into this spacefrom adjacent zones.EVACUATION MODE — Evacuation mode removes smokeor undesirable air from interior spaces without reintroducingunsuitable air. The economizer and power exhaust are requiredfor this function. The economizer and power exhaust arestandard on 48FM and 50FM,FS units. The economizer is afactory-installed option and the power exhaust is a factory-installed option or field-installed accessory on 48FK,JK and50FK,JK units. Evacuation is accomplished by:• turning supply fan off• opening the economizer• running the exhaust fans• opening the exhaust dampers1215034-048: TB3054-104: TB4 TRANSDUCERR P BMSCONTROL(4 TO 20 MAOR2 TO 10 VDCSIGNAL)LIGHT4 5TB2 TB2RELAYRSIGNAL TO BMSLEGENDFig. 30 — Remote SASP WiringP — Manual PotentiometerR — Fixed ResistorField WiringLEGENDFig. 31 — External Alarm IndicationR — Fixed ResistorFactory WiringField Wiring