ABB AV2123000 Positioner User Manual

CAM CHARACTERIZATION
100
90
80
70
60
%OFPISTON
OR VALVE
TRAVEL
50
40
30
20
10
0
0 10 20 30 40 50 60 70 80 90 100
%OFCONTROLLEDMEDIUM
T00795A
Figure C-4. Regulated Device Characteristics
2. Plot the exact control medium versus control signal characteristic
given or desired for the application. This is usually a linear
function (Fig. C-5).
NOTE: If angularity is introduced into the drive linkage, replot the
controlled medium versus piston travel curves. In all cases,
avoid overstroking the final control device.
100
90
80
70
60
%OF
SIGNAL
50
40
30
20
10
0
0 10 20 30 40 50 60 70 80 90 100
% OF CONTROLLED MEDIUM T00794A
Figure C-5. Desired Control
CAM SELECTION
C - 4