Carrier 30XA080-500 Controls, Start-up, Operation, Service And Troubleshooting Instructions

Also see for 30XA325: Installation instructions Installation instructions

Carrier 30XA080-500 Controls, Start-up, Operation, Service And Troubleshooting Instructions Manual pdf 32 page image

Water Temperature Difference ResetLI.."O(/)rrg)c_3(EXAMPLE)2100 4 10Entering - Leaving Water Temperature (deg F)Fig. 16 -- Water Temperature Difference (Delta T) ResetTo use 4 to 20 mA Temperature Reset in addition to theEnergy Management Module, four variables must be config-ured. They are: Cooling Reset Type (Collfiguration _RSET_CRST), CmTent No Reset Val (Setpoints _COOL _CR VI ),Current Full Reset Val (Setpoints_COOL_CRV2) andDegrees Cool Reset (Setpoints_COOL_DGRC). In thefollowing example, at 4 mA no reset takes place. At 20 mA,5 ° F (2.8 ° C) chilled water set point reset is required. SeeFig. 20 and Table 24.Cme should be taken when intell"acing with other controlsystems due to possible power supply differences such as afull wave bridge versus a half wave rectification. Connec-tion of control devices with different power supplies mayresult in pemlanent damage. Col_fhrtLink TM controlsincorporate power supplies with half wave rectification. Asignal isolation device should be utilized if the signalgenerator incorporates a full wave bridge rectifiel:Demand Limit -- Demand Limit is a feature that allowsthe unit capacity to be limited during periods of peak energyusage. There are three types of demand limiting that canbe configured. The first type is through 2-step switchcontrol, which will reduce the maximum capacity to 2 user-configurable percentages. The second type is by 4 to 20 mAsignal input which will reduce the maximum capacity linearlybetween 100% at a 4 mA input signal (no reduction) down tothe user-configurable level at a 20 mA input signal. The thirdtype uses the CCN I_adshed module and has the ability tolimit the cmTent operating capacity to maximum and furtherreduce the capacity if required.NOTE: One-step Demand Limit is stan&ud.The 2-step switch control and 4 to 20-mA input signal typesof demand limiting require the Energy Management Module(EMM).To use Demand Limit, select the type of demand limiting touse. Then configure the Demand Limit set points based on thetype selected.1-STEP SWITCH CONTROLLED -- One-step Demand Lim-it control does not require the Energy Management Module. Toconfigure Demand Limit for 1-step switch control two par_mle-ters must be configured: Demand Limit Select (Configura-tion _RSET--eDMDC), and Switch Limit Setpoint 1(Seq_oints--+MISC--eDLSI). Demand Limit step is controlledby a relay switch input field wired to TB5-5 and TB5-14for Switch 1. See the 2-Step Switch Controlled section forexample.2-STEP SWITCH CONTROLLED-- If using 2-step De-mand Limit control, an Energy Management Module must beinstalled. One-step Demand Limit control does not require theEnergy Management Module. To configure Demand Limit for2-step switch control, three parameters must be configured:Demand Limit Select (Configuration--eRSET--eDMDC),Switch Limit Setpoint 1 (Se&oints--eMISC--eDLSI) andSwitch Limit Setpoint 2 (Se&oints--eMISC--eDLS2). In thefollowing exm_lple, Demand Limit Switch 1 is 60% andDemand Limit Switch 2 is 40%. Demand Limit steps arecontrolled by two relay switch inputs field wired to TB5-5 andTB5-14 for Switch 1 and TB6-14 and TB6-15 for Switch 2.See Table 25.For Demand Limit by percent capacity switch control, clos-ing the % capacity demand limit contact will put the unit on thefirst demand limit level. The unit will not exceed the percent-age of capacity entered as Demand Limit Switch 1 set point.Closing contacts on the second demand limit switch preventsthe unit from exceeding the capacity entered as Demand LimitSwitch 2 set point. The demand limit % capacity that is set tothe lowest demand takes priority if both demand limit inputsare closed. If the demtmd limit percentage does not match unitstaging, the unit will limit capacity to the closest capacity stepwithout exceeding the value. To disable demand limit config-ure DMDC to 0.32