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15.2.7 C
– P
ASCADE
OWER BALANCE MODE
Several different power control modes can be selected to operate the cascade system.
•
Power mode 0:
Power control disabled, each boiler modulates based on the system setpoint.
•
Power mode 1:
Power control algorithm to have a minimum amount of boilers/boilers active.
•
Power mode 2:
Power control algorithm to have a maximum amount of boilers/boilers active.
•
Power mode 3:
Power control algorithm to have a balanced amount of boilers/boilers active.
Cascade – Boiler rotation
The boiler rotation function can change the start/stop sequence for the cascade boilers.
The parameter Boiler_Rotation_Interval sets the number of days after which the sequence is updated. When
Boiler_Rotation_Interval is set to 0 boiler rotation is disabled.
When the parameter Burner_Rotation_Interval is updated the boiler rotation days left will be initialized to the new
Burner_Rotation_Interval setting.
When for example Burner_Rotation_Interval = 5 the start sequence is as following (x is the last boiler):
Days
Start/Stop sequence
Day 0-5
1-2-3-4-5..x
Day 5-10
2-3-4-5..x-1
Day 10-15
3-4-5..x-1-2
Day 15-20
4-5..x-1-2-3
Day 20-25
5..x-1-2-3-4
Table 15-4
With parameter First_Depending_To_Start the current depending that is first to start in the sequence is selected.
When the boilers are rotated the parameter First_Depending_To_Start is automatically updated to the next
depending. When boiler rotation is disabled the parameter First_Depending_To_Start is reset to 0.
When the First_Depending_To_Start is manually changed the control will clear all demand of the cascade control.
After this is will start cascade demand generation with the new selection for First_Depending_To_Start.
15.3.1 N
EXT DEPENDING TO START SELECTION
When the cascade Burner_Rotation_Interval has passed the control will perform the cascade rotation. At this
moment the next available control based on the current First_Depending_To_Start is selected.
A depending control is available when the control is present on the communication bus and the control is not
blocked by an error.
When the control is not available the control is skipped as the next First_Depending_To_Start.
Relevant variables
Specific Parameters
Burner_Rotation_Interval
First_Depending_To_Start
Table 15-5
96
Level
(Default) Value
2: Installer
5
2: Installer
1
E93.1601EN032.C VGH installation manual
Range
0...30
(0: Disabled)
1...8/16
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