Carrier 50PD05 Operating And Service Instructions

Also see for 48PD05: User manual User's information manual Installation instructions

Loadshed Group Number (S.GRP)This corresponds to the loadshed supervisory devices that resideelsewhere on the CCN network and broadcast loadshed and redlinecommands to its associated equipment parts. This variable willdefault to zero which is an invalid group number. This allows theloadshed flmction to be disabled until configured.Redline Max Capacity (R.MXC)This configuration tells the unit the maximumcooling/dehunfidification capacity allowed active during aloadshed condition.Redline Max Heat Stages (R.MXH)This configuration tells the unit the maximum heating stagesallowed to be on during a redline condition.Loadshed Max Heat Stages (R.MXHThis configuration tells the unit the maximum heating stagesallowed to be on during a loadshed condition.The two Demand Linfiting methods can be active simultaneously.The lowest cool capacity and heat stage linfits imposed by eithermethod are applied, and these "effective linfits" are shown in thepoints CAPLIMIT (Run Status--+COOL--+LMT.C) andHSTGLIMT (Run Status--+HEAT--+LMTJt), respectively. Innormal running mode, these limits will prevent capacity/stagesfrom being added, or capacity/stages to be removed, as applicable.In test mode, these limits are ignored, and the user may continue tooperate at full load.The point MODEDMDL (Run Status--+MODE--+DJ, MT) is usedto show if any Demand Limiting is in effect that prevents the unitfrom operating either cooling or heating at full-capacity.IMPORTANT: MODEDMDL may reflect that staging is NOTlimited even though Loadshed is active or the network points arebeing forced, if the capacity/stage limits in effect are not less thanthe capacity/stages present in the unit.If a more drastic mode of Demand Limiting is required, thenetwork point HVACDOWN (Run Status--+MODE--+HV.DN) canbe used to prohibit the unit from selecting any HVAC mode, thuspreventing the operation of the supply fan, compressors, condenserfans, and heat stages. This point must also be forced, and is resetautomatically when not forced, and at POR.Alarm HandlingThere are a variety of different alerts and alarms in the system.Alerts are indicated by TXXX (where XXX is the alert number) onthe display and generally signify that the improperly functioningcircuit can restart without human interaction. If an alarm occurs,indicated by AXXX (where XXX is the alarm number), thedamaged circuit will generally not restart without an alarm reset viathe Scrolling Marquee display or CCN.The response of the control system to various alerts and alarmsdepends on the seriousness of the particular alert or alarm. In themildest case, an alert does not affect the operation of the unit in anymanner. An alert can also cause a "strike." A "striking" alert willcause the circuit to shut down for 15 minutes. This feature reducesthe likelihood of false alarms causing a properly working system tobe shut down incorrectly. If three strikes occur before the circuithas an opportunity to show that it can flmction properly, the circuitwill strike out, causing the shutdown alarm for that particularcircuit. Once activated, the shutdown alarm can only be cleared viaan alarm reset.However, circuits with strikes will be given an opportunity to resettheir strike counter to zero. As discussed above, a strike typicallycauses the circuit to shut down. Fifteen nfinutes later, that circuitwill once again be allowed to run. If the circuit is able to run for 1nfinute, its replacement circuit will be allowed to shut down (if notrequired to run to satisfy requested stages). However, the"troubled" circuit must run continuously for a user defined time(Configuration-+COOL-+RST.C) with no detectable problemsbefore the strike counter will be reset to zero. Default value is 5nfinutes.CCN Alarm BroadcastOperators of CCN networks nfight not want to be notified of"striking" alerts for refrigerant circuits until the circuit has beenshut down due to 3 strikes. Set the cooling configuration of AlertEach Strike (Configuration--+COOL--+ALM.N on display,ALM_NOW on CCN) to YES to broadcast each circuit strike alert.Set Alert Each Strike to NO to broadcast only circuit shut down.Alert Each Strike configuration is ignored during Service Test andall alerts are broadcast.Alarm Relay OutputThe alarm relay output is a normally open 24 vac output betweenfield connection terminal board terminals C and X. Selection ofwhich alerts and alarms will result in closing of the alarm relaymay be set in the Alarm Relay Configuration(Configuration--,ALM.O). Setting a configuration to YES willresult in the alarm output relay, ALRM, status of ON and 24 vacbetween C and X when that particular condition is in an alarmstate. Setting a configuration to NO will result in no action by thealarm output relay for that particular condition.IMPORTANT: An accessory filter switch can be used along withthe alarm relay output function to indicate dirty filter service need.See the Troubleshooting section for more information on viewing,diagnosing, and clearing alerts and alarms.TROUBLESHOOTINGThe Scrolling Marquee display shows the actual operatingconditions of the unit while it is running. If there are alarms orthere have been alarms, they will be displayed in either the currentalarm list or the history alarm list. (See Table 8.) The Service Testmode allows proper operation of the compressors, fans, and othercomponents to be checked while the unit is not operating. SeeService Test.Complete Unit StoppageThere are several conditions that can cause the unit not to provideheating or cooling:• If an alarm is active which causes the unit to shut down,diagnose the problem using the information provided in Alarmsand Alerts section below.• Cooling and heating loads are satisfied.• Programmed occupancy schedule.• General power failure.• Tripped CB1 or CB2 (24-volt transformer circuit breakers).• Unit is turned off through the CCN network.• If outdoor-air temperature is less than the Compressor LockoutTemperature (CA.LO) configuration value, unit cannot cool.• If outdoor-air temperature is greater than the Heating LockoutTemperature (HT_LO) configuration value, unit cannot heat.Restart ProcedureBefore attempting to restart the machine, check the alarm list todetermine the cause of the shut down. If the shutdown alarm for aparticular control function has occurred, deternfine and correct thecause before allowing the unit to run under its own control again.When there is problem, the unit should be diagnosed in ServiceTest mode. The alarms nmst be reset before the control functioncan operate in either Normal mode or Service Test mode.Control Module CommunicationRed LEDProper operation of the MBB, ECB and AUX1 control boards canbe visually checked by looking at the red status LEDs. Whenoperating correctly, the red status LEDs should blink in unison at arate of once every 2 seconds. If the red LED on the ECB and24