CAM CHARACTERIZATION
CAM SELECTION
C
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3
CAM SELECTION
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.
Table C-1. Relationship of Input to Output for I/P Converter (AV3)
% of Control
Signal
I/P Converter
% of Control
Signal
I/P Converter
Input (mA)
Output (psig)
Input (mA)
Output (psig)
0
4.0
3.0
60
13.6
10.2
10
5.6
4.2
70
15.2
11.4
20
7.2
5.4
80
16.8
12.6
30
8.8
6.6
90
18.4
13.8
40
10.4
7.8
100
20.0
15.0
50
12.0
9.0
Figure C-4. Regulated Device Characteristics
1 0 0
4 0
1 0
2 0
3 0
9 0
5 0
6 0
7 0
8 0
0
% O F P IS TO N
O R VA LV E
T R AV EL
% O F C O N T R O L LED M ED IU M
T 00 79 5 A
0
2 0
3 0
4 0
5 0
1 0
6 0
7 0
8 0
9 0
1 0 0