Specifications
24
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) — To con-
figure demand limit for 2-stage switch control set the Demand
Limit Select (Configuration
RSET
DMDC) to 1. Then
configure the 2 Demand Limit Switch points (Configura-
tion
RSET
DLS1) and (Configuration
RSET
DLS2)
to the desired capacity limit. See Table 17. Capacity steps are
controlled by 2 relay switch inputs field wired to LVT as shown
in Fig. 5.
For demand limit by 2-stage switch control, closing the first
stage demand limit contact will put the unit on the first demand
limit level. The unit will not exceed the percentage of capacity
entered as Demand Limit Switch 1 set point (DLS1). Closing
contacts on the second demand limit switch prevents the unit
from exceeding the capacity entered as Demand Limit Switch
2 set point. The demand limit stage that is set to the lowest de-
mand 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 DMDC to 0. See
Table 17.
EXTERNALLY POWERED DEMAND LIMIT (4 to
20 mA Controlled) — To configure demand limit for 4 to 20
mA control set the Demand Limit Select (Configura-
tion
RSET
DMDC) to 2. Then configure the Demand
Limit at 20 mA (Configuration
RSET
DM20) to the
maximum loadshed value desired. Connect the output from an
externally powered 4 to 20 mA signal to terminal block LVT,
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 17 and Fig. 18.
DEMAND LIMIT (CCN Loadshed Controlled) — To con-
figure Demand Limit for CCN Loadshed control set the De-
mand Limit Select (Configuration
RSET
DMDC) to 3.
Then configure the Loadshed Group Number (Configura-
tion
RSET
SHNM), Loadshed Demand Delta (Configu-
ration
RSET
SHDL), and Maximum Loadshed Time
(Configuration
RSET
SHTM). See Table 17.
The Loadshed Group number is established by the CCN
system designer. The ComfortLink controls will respond to a
Redline command from the Loadshed control. When the
Redline command is received, the current stage of capacity is
set to the maximum stages available. Should the loadshed con-
trol send a Loadshed command, the ComfortLink controls will
reduce the current stages by the value entered for Loadshed
Demand delta. The Maximum Loadshed Time is the maximum
length of time that a loadshed condition is allowed to exist. The
control will disable the Redline/Loadshed command if no
Cancel command has been received within the configured
maximum loadshed time limit.
Cooling Set Point (4 to 20 mA) — A field supplied
and generated, externally powered 4 to 20 mA signal can be
used to provide the leaving fluid temperature set point. Connect
the signal to LVT-10,8 (+,–). See Table 17 for instructions to
enable the function. Figure 19 shows how the 4 to 20 mA sig-
nal is linearly calculated on an overall 10 F to 80 F range for
fluid types (Configuration
OPT1
FLUD) 1 or 2. The set
point will be limited by the fluid (FLUD) type. Be sure that the
chilled water loop is protected at the lowest temperature.
LEGEND
LWT — Leaving Water (Fluid) Temperature
Fig. 15 — Outdoor-Air Temperature Reset
LEGEND
LWT — Leaving Water (Fluid) Temperature
Fig. 16 — Space Temperature Reset
LWT
LWT
LEGEND
Fig. 17 — Standard Chilled Fluid
Temperature Control — No Reset
EWT —
Entering Water (Fluid) Temperature
LWT —
Leaving Water (Fluid) Temperature
CAUTION
Care should be taken when interfacing with other manufac-
turer’s control systems, due to possible power supply
differences, full wave bridge versus half wave rectification.
The two different power supplies cannot be mixed.
ComfortLink controls use half wave rectification. A signal
isolation device should be utilized if a full wave bridge
signal generating device is used.