Beckett RWF40 Manual - Manual (Page 48)

48/57 CC1B7865en 01.09.2005 HVAC Products
9. Self-setting function
)
« tunE» is only possible in high-fire operation, in the «modulating burner» mode.
The self-setting function «
tunE» is a proper software function unit that is integrated into
the controller. In the «modulating» mode, « tunE» tests the response of the controlled
system to steps of the positioning signal according to a special procedure. A complex
control algorithm uses the response of the controlled system (actual value) to calculate
and store the control parameters for a PID or PI controller (set dt = 0!). The «
tunE»
procedure can be repeated any number of times.
Self-setting Start
Identification of
the controlled
system
PID controller
settings
Controller
Controlled
system
Y
W
X
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The «
tunE» function uses 2 different methods that are automatically selected depending
on the dynamic state of the actual value and the deviation from the setpoint at the start.
«
tunE» can be started from within any dynamic actual value sequence.
If there is a large difference between actual value and setpoint when «tunE» is
activated, a switching line is established about which the controlled variable performs
forced oscillations during the self-setting procedure. The switching line is set at such a
level that the actual value should not exceed the setpoint.
Switching
level w
x
Start
t
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With a
small deviation between setpoint and actual value (after the controlled system
has stabilized, for instance), a forced oscillation is performed about the setpoint.
9.1 Self-setting function in high-fire operation
2 procedures