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CASCADE CONNECTION
4.5.2
Par 148 = 1
In this mode the system manages the cascade so that the min-
imum number of modules is on.
The first difference in relation to mode 0 refers to the logic with
which the modulation of Depending modules within the cas-
cade is managed.
In fact, while each thermal module modulates with its own PID
in mode 0, no more than two Depending modules modulate
with the same criteria in mode 1, while the remaining modules
operate at maximum power. The diagram is represented in the
following figure:
Managing
PID
Managing
PID
PID
Managing
100%
PID
PID
Managing
100%
100%
PID
PID
Managing
100%
100%
100%
PID
PID
Practically speaking, if more than two thermal modules are on,
only two thermal modules are controlled via PID, while the oth-
ers receive a signal to move to maximum power.
The second difference refers to the start-up/shutdown rules of
the individual modules.
In any case, the start-up and shutdown rules are managed ac-
cording to the indications shown in the previous graph. The dif-
ference is that it is also possible to have start-ups/shutdowns of
the Depending modules in the "balancing" zone.
This additional start-up criteria (valid in the balancing band
only) ensures that a module is started-up when any one of
the two modules controlled by a PID adjustment has reached
a threshold power (Par 82) once a specific wait time defined by
Par 75 has elapsed.
Similarly (still within the balancing band), a module is shut-
down if both modules controlled by a PID adjustment have
reached a percentage of power which is below the minimum
power threshold (Par 83) once a specific wait time defined by
Par 75 has elapsed.
4.5.3
Par 148 = 2
In this mode the system manages the cascade so that the max-
imum number of modules is on.
This mode is similar to mode 0 apart from the start-up and
shutdown rules.
In this case the rules based on the information illustrated by the
previous graph are still valid, with the following differences (in
any case, always applicable to the "balancing" band only):
To add an additional depending module, the managing module
evaluates whether the sum of the power (calculated on the ba-
sis of the fan speed) of all the active thermal modules is greater
than the product between the number of the active depend-
ing modules increased by one and the minimum power value
(Par 152) increased by a hysteresis value (defined by Par 153). [Σ(
P1,P2,...Pn) > (n+1) * (Par 152) + (Par 153)].
To shutdown a depending access, the managing module eval-
uates whether the sum of the power (calculated on the basis of
the fan speed) of all the active thermal modules is less than the
product between the number of the active depending modules
and the minimum power value (Par 152). [Σ( P1,P2,...Pn) < (n) *
(Par 152)].
9
We must consider that the percentage of power varies from
a minimum of 1% and a maximum of 100% and therefore,
the parameter values 152 and 153 are not to be taken as the
percentage of absolute power.
96
4.6 Parameters specific to cascade systems
Parameters are listed base on the reference menu.
Reference Menu
M1
Parameters Menu
M2
Cascaded module configuration menu
M3
Cascaded boiler configuration menu
M4
Appliance configuration menu
Par.
Display visualis-
Menu
Description
No.
ation
Activates the emergency mode. This mode comes on
when communication between Managing and the
Permit Emer-
M2
72
primary circuit's probe is lost. In this event, if Par. 72
gency Mode
is set to "Yes", the cascade is initiated, working to the
fixed set-point determined by Par. 74.
Emergency Set-
M2
74
Set-point active in emergency mode.
point
Delay Per Start
Defines the stand-by time in seconds to restart the
M2
75
Next Mod.
subsequent cascade module in normal start mode.
Delay Per Stop
Defines the stand-by time in seconds to switch off the
M2
76
Next Mod.
last cascade module on in normal Off mode.
Delay Quick Start
Defines the stand-by time in seconds to restart the
M2
142
Next
next cascade module in quick start mode.
Delay Quick Stop
Defines the stand-by time in seconds to switch off the
M2
143
Next
last cascade module on in Quick Stop mode.
Defines by how many degrees the temperature meas-
Hyst. Down Start
ured by the primary circuit's probe must fall below the
M2
77
Module
set-point in order for the subsequent module to be
started after the time interval set by Par. 75.
Defines by how many degrees the temperature meas-
Hyst. Up Stop
ured by the primary circuit's probe must go above the
M2
78
Module
set-point in order for the subsequent module to be
switched off after the time interval set by Par. 76.
Defines by how many degrees the temperature meas-
ured by the primary circuit's probe must go below the
Hyst. Down
M2
144
set-point in order for the subsequent module to be
Quick Start
started after the time interval set by Par. 142 (quick-
start mode).
Defines by how many degrees the temperature meas-
ured by the primary circuit's probe must go above
Hyst. Up Quick
M2
145
the set-point in order for the subsequent module to
Stop
be switched off after the time interval set by Par. 143
(quick stop mode).
Defines by how many degrees the temperature meas-
ured by the primary circuit's probe must go above the
M2
146
Hyst. Up Stop All
set-point in order for all "On" modules to be switched
off at the same time.
Defines the number of modules of which the cascade
M2
147
Number of Units
consists.
M2
148
Power Mode
Defines the cascade operation mode.
Defines the maximum decrease in the primary circuit's
Max. Setp. Offset
M2
79
cascade set-point. Is based on the primary circuit's
Down
probe reading.
CASCADE CONNECTION
Access type
U
End user
I
Installer
O
Manufacturer
Factory
Access
Range
UM
setting
type
Yes/No
Yes
U
20...65
70
°C
I
5...255
120
Sec.
I
5...255
30
Sec.
I
5...255
60
Sec.
I
5...255
15
Sec.
I
0...40
5
°C
I
0...40
4
°C
I
0...40
20
°C
I
0...40
6
°C
I
0...40
8
°C
I
1...16
8
I
0 Disabled 1
Min burners
2
I
2 Max burn-
ers
0...40
2
°C
I
97
Category
Cascade
Cascade
Cascade
Cascade
Cascade
Cascade
Cascade
Cascade
Cascade
Cascade
Cascade
Cascade
Cascade
Cascade
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