Strebel S-CB 100, Инструкция по установке и эксплуатации

Страница: 32 / 36

32
13.
Cascade control
13.1 Output control
The total cascade set-up will act as one single big boiler, switching on- and off boilers, depending on the total
load necessary to adjust and keep the flow temperature at the calculated value.
When the heat demand rises, more boilers are switched on, and when heat demand falls, one or more
boilers will be switched off. The boiler that was switched on last, will be switched off first (see table below).
13.2 Boiler sequence
To distribute operating hours equally over all boilers, the working sequence of the boilers will change every
two hours.
Hour Switching ON sequence Switching OFF sequence
X
Master – Slave 1 – Slave 2 – Slave 3 –
Slave 4 – Slave 5 – Slave 6 – Slave 7 Slave 7 – Slave 6 – Slave 5 – Slave 4 –
Slave 3 – Slave 2 – Slave 1 – Master
X+1
Slave 7 – Master – Slave 1 – Slave 2 –
Slave 3 – Slave 4 – Slave 5 – Slave 6 Slave 6 – Slave 5 – Slave 4 – Slave 3 –
Slave 2 – Slave 1 – Master – Slave 7
X+2
Slave 6 – Slave 7 – Master – Slave 1 –
Slave 2 – Slave 3 – Slave 4 – Slave 5 Slave 5 – Slave 4 – Slave 3 – Slave 2 –
Slave 1 – Master – Slave 7 – Slave 6
X+3
Slave 5 – Slave 6 – Slave 7 – Master –
Slave 1 – Slave 2 – Slave 3 – Slave 4 Slave 4 – Slave 3 – Slave 2 – Slave 1 –
Master – Slave 7 – Slave 6 – Slave 5
……….. ………………………………………………… …………………………………………………
Table 5. Boiler sequence example of an eight-boiler cascade.
In this table, a total of eight boilers (one master, seven slaves) is mentioned as an example, in practice the
maximum number in a cascade, without extra (external) control, is twelve boilers.