Demand Limit; Demand Limit (2-Stage Switch Controlled); Externally Powered Demand Limit - Carrier GEMINI 38APS025-065 Installation Instructions Manual

Demand Limit is a feature that allows
Demand Limit —
the unit capacity to be limited during periods of peak energy
usage. There are 3 types of demand limiting that can be
configured. 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 between
100% at a 4 mA input signal (no reduction) down to the user-
configurable level at a 20 mA input signal. The third type uses
the 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 signal
types of demand limiting require the energy management
module (EMM).
To use Demand Limit, select the type of demand limiting to
use. Then configure the Demand Limit set points based on the
type selected.

DEMAND LIMIT (2-Stage Switch Controlled)

figure Demand Limit for 2-stage switch control, set the Demand
Limit Select (Configuration
configure the 2 Demand
 
(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) strip
terminal 3-6. Refer to the unit wiring diagram for these connec-
tions.
For Demand Limit by 2-stage switch control, closing the
first 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. Closing
contacts on the second demand limit switch prevents the unit
KEYPAD
MODE
ENTRY
CONFIGURATION
ENTER
*Seven items skipped in this example.
To con-
 
RSET DMDC) to 1. Then
Limit Switch points
Table 13 — Configuring Demand Limit
KEYPAD
SUB-MODE
ENTRY
DISP
UNIT
CCN
OPT1
OPT2
M.MST
RSET
ENTER
from exceeding the capacity entered as Demand Limit Switch
2 set point. The demand limit stage that is set to the lowest
demand takes priority if both demand limit inputs are closed. If
the demand limit percentage does not match unit staging, the
unit will limit capacity to the closest capacity stage.
To disable demand limit, configure the DMDC to 0. See
Table 13.
EXTERNALLY POWERED DEMAND LIMIT (4 to
20 mA Controlled)
20 mA control, set the Demand Limit Select (Configura-
 
tion RSET
Limit at 20 mA (Configuration
maximum loadshed value desired. Connect the output from an
externally powered 4 to 20 mA signal to terminal block LVT
strip terminals 7 and 8. Refer to the unit wiring diagram for
these 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 Table
13 and Fig. 33.
Care 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 signal
isolation device should be utilized if a full wave bridge
signal generating device is used. Failure to comply could
result in possible equipment damage.
ITEM DISPLAY ITEM EXPANSION
CRST X Cooling Reset Type
DMDC* X Demand Limit Select
DM20 XXX % Demand Limit at 20 mA
SHNM XXX Loadshed Group Number
SHDL XXX% Loadshed Demand Delta
SHTM XXX MIN Maximum Loadshed Time
DLS1 XXX % Demand Limit Switch 1
DLS2 XXX % Demand Limit Switch 2
31
To configure Demand Limit for 4 to
DMDC) to 2. Then configure the Demand
 
RSET
CAUTION
Default: 0
0 = None
1 = Switch
2 = 4 to 20 mA Input
3 = CCN Loadshed
Default: 100%
Range: 0 to 100
Default: 0
Range: 0 to 99
Default: 0%
Range: 0 to 60%
Default: 60 min.
Range: 0 to 120 min.
Default: 80%
Range: 0 to 100%
Default: 50%
Range: 0 to 100%
DM20) to the
COMMENT