Burkert Type 8611 - Manual (Page 53)

53
FunctionsoftheConfigurationLevel
parameterization: Single-acting, pneumatically operated control valves with "normal closed" function can be
operated. Two control valves are required for the pneumatic control of the process valve (see Figure 34).
8611
Set-point
value
Actual value
y 1 (ms)
y 2 (ms)
P R
Aeration
(NC operating
principle)
Deaeration
(NO operating
principle)
Control valves
Controller setting:
MODE = F, PCV, TMN1,
TMN2, FREQ
Figure 34: Example of a quasi-continuous control using process valve
The process valve is opened and closed with two control valves. The control valve for aeration opens and that for
deaeration closes the process valve.
A 3-state controller with P-structure is provided as controller, which calculates a time-proportional control (PTM)
as manipulated variable for the control valves depending on the set-point/actual value deviation.
By default, the control valves are available as control block (Bürkert Type 8810) for the control of 1, 2, 4 or 6
process valves. The design for the control of a process valve is shown in Figure 35.
for optimal control of process valves, the opening and closing times must be set in the pcv menu by
setting the minimum control time:
display description control time [ms]
Bürkert
control blocks
type 8810 Other valves
TMN1 Minimum control time for aeration valve in ms 5 ms (default)
(0 ... 9999 ms) Use the times specified
in the data sheet of the
valve
TMN2 Minimum control time for bleed valve in ms 5 ms (default)
(0 ... 9999 ms)
Table 16: Minimum control time for control valves
The minimum control time describes the time within that the control valve just starts opening.
For the Bürkert control blocks Type 8810, the minimum control time of 5 ms has been set as default in the
controller and does not have to be changed.
english
Type 8611