Demand Limit - Carrier AquaForce 30XV140 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

SPACE TEMPERATURE RESET — The control system is
also capable of temperature reset based on space temperature.
The energy management module (EMM) and accessory sensor
(P/N 33ZCT55SPT) are required for temperature reset using
space temperature. This sensor measures the space (room) tem-
perature for the purpose of set point reset. Only units with the
optional energy management module are fitted with this sensor.
To use Space Temperature Reset, four variables must be
configured: Cooling Reset Select, Space T No Reset Value
(space temperature at which no temperature reset is required),
Space T Full Reset Value (space temperature at which full tem-
perature reset is required), and Cooling Reset Deg Value (the
maximum amount of temperature reset desired).
To configure this option with the Touch Pilot display:
DISPLAY NAME PATH
Cooling Reset
Select
0=None, 1=OAT
2=Delta T,
3=4-20mA control
4=Space Temp
Main Menu
Space T No
Configuration Menu
Reset Value
Reset Configuration
Space T Full
Reset Value
Cooling Reset
Deg Value
In the space temperature reset example in Fig. 35, a reset of
6° F (3.3° C) is applied when the space temperature is 68 F
(20.0 C) and no reset takes place when the space temperature is
72 F (22.2 C).
There are three types of demand limit-
Demand Limit —
ing that can be configured. The first type is through switch con-
trol, which will reduce the maximum capacity to up to 3 user-
configurable percentages. The second type is by 4 to 20 mA
signal input which will reduce the maximum capacity linearly
between 100% at a 4 mA input signal (no reduction) down to
7
6
5
4
Cooling Reset
Deg. Value
3
(cr_deg)
2
1
0
60
VALUE
Low = 0° F (0° C)
Default = 0° F (0° C)
High = 4 F (2.2 C)

Low = 14 F (7.8 C)

Default = 14 F (7.8 C)
High = 125 F (69.4 C)
Low = 14 F (7.8 C)
Default = 14 F (7.8 C)
High = 125 F (69.4 C)
Low = 30 F (16.7 C)
Default = 0° F (0° C)
High = 30 F (16.6 C)
Space T Full Reset Value
(spahr_fu)
65
Space Temperature (deg F)
Fig. 35 — Example: Space Temperature Reset
the user-configurable level at a 20 mA input signal. The third
type uses the CCN Loadshed module and has the ability to lim-
it the current operating capacity to maximum and further re-
duce the capacity if required. Demand limit control can be
based on a calculated capacity level.
SWITCH CONTROLLED DEMAND LIMIT — The con-
trol system is capable of demand limit based on a field-sup-
plied switch for 1-step demand limit or 2 switches for 3-step
demand limit. One-step demand limit is standard. The 3-step
switch control of demand limiting requires the energy manage-
ment module (EMM). Demand limit steps are controlled by
two relay switch inputs field wired to TB5-5 and TB5-6 for
Switch 1 (LIM_SW1) and TB6-14 and TB6-15 for Switch 2
(LIM_SW2).
For demand limit by switch control, closing the first de-
mand limit contact will put the unit on the first demand limit
level by capacity. The unit will not exceed the percentage of ca-
pacity entered as demand limit switch 1 set point. Closing con-
tacts on the second demand limit switch prevents the unit from
exceeding the demand limit entered as demand limit switch 2
set point. If both demand limit switch contacts are closed the
unit will not exceed the limits set by the switch limit set point 3.
See the table below.
CONTACT
NONE
LIM_SW1 Open
LIM_SW2 Open
If the demand limit percentage is set below minimum
unit operation, the unit will go into override mode. See
Override #91: Demand Limit section on page 42.
To use demand limit, select the type of demand limiting to
use by configuring the Demand Limit Select variable (Main
Menu  Configuration Menu  General Configuration 
Demand Limit Type Select) to Switch. Configure the demand
limit set points based on the type selected.
Space T No Reset Value
70
38
ACTIVE DEMAND LIMIT
LIMIT 1 LIMIT 2
Close Open
Open Close
(spahr_no)
75 80
a30-5884
LIMIT 3
Close
Close