8.10 Cascade operation
The DIEMATIC Evolution control panel installed as master is able to
control up to seven generators in cascade.
The system sensor is connected to the master generator.
All the generators in the cascade are connected by an S-BUS cable.
The generators are automatically numbered:
Number 1 = master generator
Number 2 = not assigned
Number 3 = first slave generator
Number 4 = second slave generator, and so on.
The cascade can be controlled in two different ways:
Traditional control: successive addition of supplementary generators.
Parallel control: simultaneous addition of supplementary generators.
The set point temperature sent to the generator can be managed in two
different ways:
Tab.27 Temperature-type cascade algorithm
Output The set point temperature sent to the generator is managed using the maximum requested
output from the heating and domestic hot water circuits
Temperature The set point temperature sent to the generator is managed using the maximum set point tem
perature requested from the heating and domestic hot water circuits, to which is added the er
ror between the measured cascade temperature and the maximum required set point temper
ature
Tab.28 Output-type cascade algorithm
Output The PI controller will calculate the output set point depending on the difference between the
measured cascade temperature and the maximum temperature setpoint required by the cir
cuits.
Temperature The set point temperature is set at 90 °C.
8.10.1 Managing a traditional cascade
1 The first generator starts running when system temperature is 3 °C
below the set point temperature.
2 After the duration defined by the NP009 parameter (here 4
minutes), the second generator starts up if ΔT < 6 °C and the
system temperature is still more than 3 °C below the set point
temperature.
3 After a second duration defined by the NP009 parameter (here 8
minutes), the third generator starts up if ΔT < 6 °C and the system
temperature is still more than 3 °C below the set point temperature.
4 The first generator shuts down when system temperature is 3 °C
above the set point temperature.
5 After the duration defined by the NP009 parameter (here 4
minutes), the second generator shuts down if ΔT < 6 K and the
system temperature is still more than 3 °C above the set point
temperature.
6 After a second duration defined by the NP009 parameter (here 8
minutes), the third generator shuts down if ΔT < 6 °C and the
system temperature is still more than 3 °C above the set point
temperature.
Fig.31
AD-3000960-01
40 8
4
x 8
-3K
+3K
6
5
4
1
2
3
8 Commissioning
7703592 - v02 - 14062018 37
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