27
7.11 - Circuit lead/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.(GEN_CONF).
•
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..
7.12 - Circuit capacity loading sequence
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.Touch.Pilot.user.interface.
(GEN_CONF).
•
Balanced loading sequence:
The control maintains
equal capacity between all circuits as the machine loads
and unloads. See also section 7.12.1.
•
Staged loading sequence:
The control loads the lead
circuit completely before the lag circuit is started. When
the.load.is.decreasing,.the.lag.circuit.is.unloaded.first..
See also section 7.12.2.
•
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. See also section 7.12.3.
7.12.1 - Dual circuit – balanced capacity loading
Loading sequence
Unloading sequence
Lead circuit (%) Lag circuit (%) Lead circuit (%) Lag circuit (%)
0
0
100
100
50
0
100
95
55
0
95
95
60
0
95
90
65
0
90
90
70
0
90
85
70
50
85
85
70
55
85
80
70
65
80
80
70
70
80
75
75
70
75
75
75
75
75
70
80
75
70
70
80
80
70
65
85
80
65
65
85
85
65
60
90
85
60
60
90
90
60
55
95
90
60
50
95
95
60
0
100
95
55
0
100
100
50
0
100
100
0
0
7.12.2 - Dual circuit – staged capacity loading
Loading sequence
Unloading sequence
Lead circuit (%) Lag circuit (%) Lead circuit (%) Lag circuit (%)
0
0
100
100
50
0
100
95
55
0
100
90
60
0
100
85
65
0
100
80
70
0
100
75
75
0
100
70
80
0
100
65
85
0
100
60
90
0
100
55
95
0
100
50
100
0
95
50
100
50
90
50
100
55
85
50
100
60
80
50
100
65
75
50
100
70
70
50
100
75
70
0
100
80
65
0
100
85
60
0
100
90
55
0
100
95
50
0
100
100
0
0
7.12.3 - Dual circuit – smart capacity loading
Loading sequence
Unloading sequence
Lead circuit (%) Lag circuit (%) Lead circuit (%) Lag circuit (%)
0
0
100
100
50
0
100
95
55
0
95
95
60
0
95
90
65
0
90
90
70
0
90
85
75
0
85
85
80
0
85
80
85
0
80
80
90
0
80
75
95
0
75
75
100
0
75
70
70
50
70
70
70
55
70
65
70
60
65
65
70
65
65
60
70
70
60
60
75
70
60
55
75
75
60
50
80
75
80
0
80
80
75
0
85
80
70
0
85
85
65
0
90
85
60
0
90
90
55
0
95
90
50
0
95
95
0
0
100
95
-
-
100
100
-
-
7.13 - High condensing temperature
61XWHZE units are high condensing units for which the
maximum.condenser.leaving.water.temperature.can.be.set.
to 85°C.
7.14 - Head pressure control
For water-cooled 61XWHZE units, condensing pressure
control.is.assured.if.the.three-way.valve.option.is.selected..
The saturated condensing temperature is controlled based
on.a.user-configurable.fixed.setpoint.(SETPOINT.menu)..
The. three-way. valve. control. can. be. configured. only. by.
Carrier.service.technicians.
