Carrier GEMINI 38APD025-100 Operating And Service Manual

Also see for GEMINI SELECT 38APD025: Installation instructions Manual Installation instructions

Carrier GEMINI 38APD025-100 Operating And Service Manual Manual pdf 31 page image

31Demand Limit — Demand Limit is a feature that allowsthe unit capacity to be limited during periods of peak energyusage. There are 3 types of demand limiting that can beconfigured. The first type is through 2-stage switch control,which will reduce the maximum capacity to 2 user-configu-rable percentages. The second type is by 4 to 20 mA signal in-put which will reduce the maximum capacity linearly between100% at a 4 mA input signal (no reduction) down to the user-configurable level at a 20 mA input signal. The third type usesthe CCN loadshed module and has the ability to limit the cur-rent operating capacity to maximum and further reduce the ca-pacity if required.NOTE: The 2-stage switch control and 4 to 20 mA input signaltypes of demand limiting require the energy managementmodule (EMM).To use Demand Limit, select the type of demand limiting touse. Then configure the Demand Limit set points based on thetype selected.DEMAND LIMIT (2-Stage Switch Controlled) — To con-figure Demand Limit for 2-stage switch control, set the DemandLimit Select (Configuration RSET DMDC) to 1. Thenconfigure the 2 Demand Limit Switch points(Configuration RSET DLS1 and DLS2) to the desired ca-pacity limit. See Table 13. Capacity steps are controlled by 2 re-lay switch inputs field wired to low voltage terminal (LVT) stripterminal 3-6. Refer to the unit wiring diagram for these connec-tions.For Demand Limit by 2-stage switch control, closing thefirst stage demand limit contact will put the unit on the first de-mand limit level. The unit will not exceed the percentage of ca-pacity entered as Demand Limit Switch 1 set point. Closingcontacts on the second demand limit switch prevents the unitfrom exceeding the capacity entered as Demand Limit Switch2 set point. The demand limit stage that is set to the lowestdemand takes priority if both demand limit inputs are closed. Ifthe demand limit percentage does not match unit staging, theunit will limit capacity to the closest capacity stage.To disable demand limit, configure the DMDC to 0. SeeTable 13.EXTERNALLY POWERED DEMAND LIMIT (4 to20 mA Controlled) — To configure Demand Limit for 4 to20 mA control, set the Demand Limit Select (Configura-tion RSET DMDC) to 2. Then configure the DemandLimit at 20 mA (Configuration RSET DM20) to themaximum loadshed value desired. Connect the output from anexternally powered 4 to 20 mA signal to terminal block LVTstrip terminals 7 and 8. Refer to the unit wiring diagram forthese connections to the optional/accessory energy manage-ment module and terminal block. The control will reduce al-lowable capacity to this level for the 20 mA signal. See Table13 and Fig. 33.Table 13 — Configuring Demand Limit*Seven items skipped in this example.  CAUTIONCare should be taken when interfacing with other manufac-turer’s control systems, due to possible power supply dif-ferences, full wave bridge versus half wave rectification.The two different power supplies cannot be mixed. Com-fortLink™ controls use half wave rectification. A signalisolation device should be utilized if a full wave bridgesignal generating device is used. Failure to comply couldresult in possible equipment damage.   MODE KEYPADENTRY SUB-MODE KEYPADENTRY ITEM DISPLAY ITEM EXPANSION COMMENTCONFIGURATION DISPUNITCCNOPT1OPT2M.MSTRSET CRST X Cooling Reset TypeDMDC* X Demand Limit SelectDefault: 00 = None1 = Switch2 = 4 to 20 mA Input3 = CCN LoadshedDM20 XXX % Demand Limit at 20 mA Default: 100%Range: 0 to 100SHNM XXX Loadshed Group Number Default: 0Range: 0 to 99SHDL XXX% Loadshed Demand Delta Default: 0%Range: 0 to 60%SHTM XXX MIN Maximum Loadshed Time Default: 60 min.Range: 0 to 120 min.DLS1 XXX % Demand Limit Switch 1 Default: 80%Range: 0 to 100%DLS2 XXX % Demand Limit Switch 2 Default: 50%Range: 0 to 100%ENTERENTER