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6 - STANDARD CONTROL OPERATIONS AND OPTIONS
6.9 - Capacity control
This function adjusts the capacity using the compressor slide valve
to keep the water exchanger temperature at its setpoint.
The control system continuously takes account of the temperature
error with respect to the setpoint, the rate of change in this error
and the difference between entering and leaving water
temperatures in order to determine the optimal moment at which
to add or withdraw capacity.
Compressors are started and stopped in a sequence designed to
equalise the number of start-ups (value weighted by their operating
time). For more information about compressors sequence, see
section 6.12.
6.10 - Night mode
Night mode allows users to configure the unit to operate with
specific parameters in a specific time period. During the night
period the unit capacity is limited.
The night period is defined by a start time and an end time that
are the same for each day of the week. The Night mode settings
or the maximum capacity value can be configured by logged-in
users via the Configuration menu (GENCONF – General
Configuration).
To set night mode settings
1. Navigate to the Configuration menu.
2. Select General Configuration (GENCONF).
3. Set Night Mode Start Hour [nh_start].
4. Set Night Mode End Hour [nh_end].
5. Set Night Capacity Limit [nh_limit].
Night Mode Start Hour [nh_start]
Night Mode End Hour [nh_end]
00:00
Night Capacity Limit [nh_limit]
0 to 100%
6.11 - Circuit leag/lag selection (multi-circuit units)
This function determines the lead and lag circuit on dual-circuit
units. It controls the start/stop sequence of the refrigeration circuits
called circuit A or circuit B.
The circuit authorised to start first is the lead circuit. Lead circuit
is used first for capacity increases and at the same time should
be decreased last when decreasing capacity. The lead/lag circuits
can be selected manually or automatically according to the unit
configuration (GENCONF).
■ Automatic lead/lag circuit determination: The control system
determines the lead circuit to equalise the operating time of
each circuit (value weighted by the number of start-ups of each
circuit). As a result, the circuit with the lowest number of
operating hours always starts first.
■ Manual lead/lag circuit determination: Circuit A or B selected
as the lead circuit. The selected circuit is always the leader.
It is the first to start and the last to stop.
6.12 - Compressor loading sequence
(multi-circuit units)
This function determines in which order the circuit capacity is
changed. Compressor loading is managed by starting/stopping
the compressors and controlling the position of the slide valve.
Three types of sequencing are available and can be configured
by the user via the SmartVu
General Configuration).
■ Balanced loading sequence: The control maintains equal
capacity between all circuits as the machine loads and unloads.
■ Staged loading sequence: The control loads the lead circuit
completely before the lag circuits are started. When the load
is decreasing, the lag circuits are unloaded first.
■ Smart circuit loading: The control loads the lead circuit
completely before decreasing in order to make the global unit
load increasing smoother. For unloading sequence the lead
circuit is increased when the lag circuit is stopped.
To set the loading sequence
1. Navigate to the Configuration menu.
2. Select General Configuration (GENCONF).
3. Set Loading Sequence [seq_typ].
Loading Sequence [seq_typ]
0 = Equal loading sequence
1 = Staged loading sequence
2 = Smart loading sequence
Staged loading sequence is incorporated under the following
conditions:
■ One of the circuits is shut down due to its failure
■ One of the circuits is in capacity override mode
■ Remaining circuits are shut down or fully charged
6.12.1 - Dual circuit – balanced capacity loading
Loading sequence (%)
Lead circuit
Lag circuit
0
0
50
0
55
0
60
0
65
0
70
0
70
50
70
55
70
65
70
70
75
70
75
75
80
75
80
80
85
80
85
85
90
85
90
90
95
90
95
95
100
95
100
100
100
100
user interface (GENCONF –
TM
Unloading sequence (%)
Lead circuit
Lag circuit
100
100
100
95
95
95
95
90
90
90
90
85
85
85
85
80
80
80
80
75
75
75
75
70
70
70
70
65
65
65
65
60
60
60
60
55
60
50
60
0
55
0
50
0
0
0
39
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