Burkert Type 8611 - Manual (Page 76)

76
FunctionsoftheConfigurationLevel
If the selected unit is changed in the UNIT menu, the proportional gain [K
p
] must be adapted accordingly.
setting aid:
An unsatisfactory dynamic of the control is improved by increasing the aproportional gain [K
p
]. The fol-
lowing must be observed:
In the event of impermissibly high overshoots after set-point value jumps or in the event of an unstable
control, the proportional gain [K
p
] should be reduced.
12.13.2. examples for the setting and calculation of the
proportional gain [K
p
]
SCV - pressure control using proportional valve
(For schematic representation see “Figure 33: Pressure control using proportional valve”)
Technical description:
• The control of the proportional valve is restricted to between 20 % and 90 %.
The control range of the valve is restricted as follows: VALV, MIN = 20 %, MAX = 90 %
(see chapter “12.17. VALV - Test function and setting of the control range”).
The physical control range thus takes place between 20% and 90% of the valve position. The defined physical
range is set in the controller as 100%.
• The process value change amounts to 250 mbar.
Calculation for K
p1
:
100 %
250 mbar
K
p1
= = 0,4 % mbar
PCV - Quasi-continuous flow-control using process valve
(For schematic representation see “Figure 34: Example of a quasi-continuous control using process valve”)
Technical description:
• Bürkert process valve with actuator size 50 mm.
• The max. process value change between closed and open position of the valve amounts to 50 l/min.
• The flow change is done within the opening time of the valve. The opening time amounts of about 2 s (see
“Table 29: Valve opening times for Bürkert process valves”).
• The control range of the valve is not restricted: VALV, MIN = 0, MAX = 0 (see chapter “12.17. VALV - Test
function and setting of the control range”).
Calculation for K
p1
and K
p2
:
100 %
50 l/mn
K
p1
= = 2 % l/mn
The proportional coefficient for opening can also be used for closing.
The controller cycle time T
reg
can be set between 1 - 2 s. For slow control loops like temperature control T
reg
must be increased.
english
Type 8611