Carrier AquaForce B Series Controls, Start-up, Operation, Service And Troubleshooting Instructions

Also see for AquaForce 30XV140: Controls, start-up, operation, service and troubleshooting instructions

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Carrier AquaForce B Series Controls, Start-up, Operation, Service And Troubleshooting Instructions Manual pdf 44 page image

44Fig. 42 — Example: Space Temperature ResetDemand LimitThere are three types of demand limiting that can be config-ured. The first type is through switch control, which will re-duce the maximum capacity to up to 3 user-configurable per-centages. The second type is by 4 to 20 mA signal input whichwill reduce the maximum capacity linearly between 100% at a4 mA input signal (no reduction) down to the user-configurablelevel at a 20 mA input signal. The third type uses the CCNLoadshed module and has the ability to limit the current oper-ating capacity to maximum and further reduce the capacity ifrequired. Demand limit control can be based on a calculatedcapacity level. If the Demand Limit is enabled and the currentcapacity requirement meets or exceeds the current DemandLimit level, the unit will unload and display Override #9: De-mand Limit section on page 48.If the demand limit percentage is set below minimum unit op-eration, the unit will go into override mode. See Override #91:Demand Limit section on page 48.SWITCH CONTROLLED DEMAND LIMITThe control system is capable of demand limit based on a field-supplied switch for 1-step demand limit or 2 switches for 3-stepdemand limit. One-step demand limit is standard. The 2 or 3-stepswitch control of demand limiting requires the EMM. Demandlimit steps are controlled By two relay switch inputs field wired toTB5-5 and TB5-14 for Switch 1 (LIM_SW1) and TB6-14 andTB6-15 for Switch 2 (LIM_SW2).For demand limit by switch control, closing the first demandlimit contact (LIM_SW1) will put the unit on the first demandlimit (LIMIT 1) by capacity. The unit will not exceed the per-centage of capacity entered as Demand Limit Switch 1 set point.Closing contacts on the second demand limit switch(LIM_SW2) and opening the Demand Limit Switch 1 preventsthe unit from exceeding the demand limit (LIMIT 2) entered asDemand Limit Switch 2 set point. If both demand limit switch(LIM_SW1 and LIM_SW2) contacts are closed the unit will notexceed the limit (LIMIT 3) set by the switch limit set point 3.See the table below.To use demand limit, select the type of demand limiting to useby configuring the Demand Limit Select variable (Main Menu Configuration Menu General Configuration DemandLimit Type Select) to Switch. Configure the demand limit setpoints based on the type selected.If using 2 or 3-step demand limit control, an energy managementmodule must be installed. The energy management module mustbe enabled in the controls. To enable the EMM navigate to Fac-tory Parameters menu (Main MenuConfiguration MenuFactory Parameters) and set Energy Management Module toYES (1).One-step demand limit control does not require the en-ergy management module. To configure demand limit for switchcontrol, three parameters for 1-step switch control must be con-figured. For 2 or 3-step control, additional set point parametersmust be configured. The parameters are: the type of DemandLimit Selection, the setting for Switch Limit Setpoint 1, the set-ting for Switch Limit Setpoint 2 (if required) and the setting forSwitch Limit Setpoint 3 (if required).To configure this option with the Carrier Controller display:In the following example, 2-step demand limit based on capac-ity is desired with the first switch closure limiting the capacityto 60%. The second switch closure is to limit the capacity to40%. Demand Limit Switch 1 is 60% and Demand LimitSwitch 2 is 40%. Since no third-step demand limit is required,Switch Limit Setpoint 3 is set at 0%.0123456757075606 80Space Temperature (deg F)Degrees Reset (deg F)Cooling ResetDeg. Value(cr_deg)Space T Full Reset Value(spahr_fu)Space T No Reset Value(spahr_no)a30-5884CONTACT ACTIVE DEMAND LIMITNONE LIMIT 1 LIMIT 2 LIMIT 3LIM_SW1 Open Close Open CloseLIM_SW2 Open Open Close CloseDISPLAY NAME PATH VALUEDemand LimitType SelectMain MenuConfiguration MenuGeneral Configura-tionDefault = 0 (None)Range None = 0Switch = 14 to 20mA = 2Switch LimitSetpoint 1Main MenuSetpoint TableDefault = 100%Range 0 to 100%Switch LimitSetpoint 2Main MenuSetpoint TableDefault = 100%Range 0 to 100%(Not required for 1-Step Control)Switch LimitSetpoint 3Main MenuSetpoint TableDefault = 100%Range 0 to 100%(Not required for 1 or 2-Step Control)DISPLAY NAME VALUEDemand Limit Type Select 1Switch Limit Setpoint 1 60%Switch Limit Setpoint 2 40%Switch Limit Setpoint 3 0%