Capacity Limitation; Capacity Control - Carrier Touch Pilot Junior Manual

8.7.2 - Reset
Reset means the active setpoint is modified so that less
machine capacity is required. In the cooling mode the
setpoint is increased, whereas in the heating mode it is
decreased.
The reset can be based on the following possibilities:
• OAT that gives the measure of the load trends for the
building.
• Return water temperature (
building load).
The reset source and the reset parameters can be
configured in the Main menu (RESETCFG – Reset
Config). In response to a change in the reset source (e.g.
OAT), the setpoint is normally reset to optimise unit
performance.
The amount of reset is determined by linear interpolation
based on the following parameters:
• A reference at which reset is zero (no reset value).
• A reference at which reset is maximum (full reset
value).
• The maximum reset value.
Reset example in Cooling mode for the space temperature
20 Reset based on OAT
0 Reset based on delta T
4 Reset based on analog input
no_reset
Legend
A Maximum reset value
B Reference for zero reset
C Reference for maximum reset
D Building load

8.8 - Capacity limitation

Touch Pilot Junior allows for the constant control of the
unit capacity by setting its maximum allowable capacity.
Capacity limitation is expressed in percentage, where a
limit value of 100% means that the unit may run with its
full capacity (no limitation is implemented).
The unit capacity can be limited:
• By means of user-controlled volt-free contacts. The
unit capacity can never exceed the limit setpoint
activated by these contacts.
By lag limit [LAG_LIM] set by the master unit in the
•
master/slave assembly. If the unit is not in the Master/
Slave assembly, the lag limit value is equal to 100%.
• By night mode limitation control. The demand limit
value in the night mode is selectable if the value is
below the selected limit.
Δ
T provides the average
25
3
20
selection full_reset
To set limit setpoints
1. Navigate to the Main menu.
Select Setpoint (SETPOINT).
2.
3. Set Switch Limit Setpoint 1 / 2 / 3 [lim_sp1 /2/ 3].
Switch Limit Setpoint 1 / 2 / 3 [lim_sp1 /2 / 3]
0 to 100% 100%
To verify lag limit set by the master unit
1. Navigate to the Main menu.
Select General Parameters (GENUNIT).
2.
Verify Lag Capacity Limit Value [LAG_LIM].
3.
Lag Capacity Limit Value [LAG_LIM]
0 to 100% 100%
To set the night mode limit
1. Navigate to the Configuration menu.
Select General Config (GENCONF).
2.
3. Set Night Capacity Limit [nh_limit].
Night Capacity Limit [nh_limit]
0 to 100% 100%
Based on the limit source, the active demand limit value
(DEM_LIM) is set to the lowest possible value.
DEM_LIM can be forced by Network.
To verify active demand limit value
1. Navigate to the Main menu.
Select General Parameters (GENUNIT).
2.
Verify Active Demand Limit Val [DEM_LIM].
3.
Active Demand Limit Val [DEM_LIM]
0 to 100% -

8.9 - Capacity control

The control adjusts the capacity to keep the water
exchanger temperature at its setpoint. Compressors are
started and stopped in a sequence designed to equalise the
number of starts (value weighted by their operating time).
8.9.1 - Circuit loading sequence
This function determines in which order the circuit
capacity is changed. Compressor loading is managed by
starting/stopping the compressors. Two types of
sequencing, i.e. balanced and staged loading sequence, are
available and can be configured by the user via the user
interface (GENCONF – General Config).
Balanced loading sequence: The control maintains equal
capacity between all circuits as the machine loads and
unloads. Balanced loading sequence is the default
sequence employed by the control.
Staged loading sequence: The control loads the lead circuit
completely before the lag circuits are started. When the
load is decreasing, the lag circuit is unloaded first. Staged
loading sequence is active when one of the circuits is shut
down due to its failure; the circuit is in capacity override
mode; or the remaining circuits are shut down or fully
charged.
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