Cam Selection - ABB AV3 Instruction Manual

Table C-1. Relationship of Input to Output for I/P Converter (AV3)
% of Control
Signal
Input (mA)
0 4.0
10 5.6
20 7.2
30 8.8
40 10.4
50 12.0

CAM SELECTION

I/P Converter
Output (psig)
3.0
4.2
5.4
6.6
7.8
9.0
In a system involving only a single actuator or cylinder, the B cam is
probably satisfactory and should be tried first. However, one of the
other cams may provide a more stable control over a wide range of
operation within a given proportional band gain adjustment on the
controller. Where the actuator or cylinder is part of a complex control
system, the three standard cams A, B and C provide a choice of con-
trol characteristics. The cam, in conjunction with a span adjustment,
are likely to meet the control characteristic required for your system.
Steps in selecting a standard cam for a particular application are:
1. With the B (linear) cam in place, determine and plot the actual
controlled medium versus piston (or valve) position characteristic by
manually adjusting valve position and measuring the controlled
medium (Fig. C-4).
10 0
9 0
8 0
7 0
6 0
% O F P IS TO N
5 0
O R VA LV E
T R AV EL
4 0
3 0
2 0
1 0
0
0
Figure C-4. Regulated Device Characteristics
CAM CHARACTERIZATION
% of Control
Signal
Input (mA)
60 13.6
70 15.2
80 16.8
90 18.4
100 20.0
10 20 30 4 0 50 6 0
% O F C O N T R O L LED M ED IU M
I/P Converter
Output (psig)
10.2
11.4
12.6
13.8
15.0
70 80 90 1 00
T 00 79 5 A
CAM SELECTION
C - 3