ABB AV2123000 Positioner User Manual

APPENDIX D - TYPE AV1 PNEUMATIC POSITION TRANSMITTER
INTRODUCTION
This appendix covers the optional pneumatic position transmitter
kit that is available for Type AV1 positioners. This option is only
available for Type AV1__0___ positioners. The topics covered
are:
• Description.
• Installation.
• Calibration.
DESCRIPTION
The Type AV1 positioner may be used as a position transmitter by
generating a pneumatic signal that is a function of an input position.
The same combinations of signal ranges and stroke spans
are offered as in the positioner application. Those signal ranges
and strokes are: 20.7 to 103.4-kilopascals (3.0 to 15.0-pounds
per square inch gage), or 20.7 to 186.2-kilopascals (3.0 to
27.0-pounds per square inch gage) output for strokes from 25.4
to 101.6 millimeters (0.5 to 4.0 inches).
The output signal may be made a square root, linear or square
function of the input position through the use of the A, B or C portion
of the cam, respectively. Other characteristics may be created
by shaping the cam (Appendix C).
The Type AV1 positioner functions as a position transmitter by
interconnecting the I input signal with the 02 output port and tapping
into this interconnection for the output signal. A plug is placed
in the 01 port. The pneumatic position transmitter kit provides the
necessary hardware (Fig. D-1). Table D-1 lists the individual part
numbers and quantities of the items identified in Figure D-1.
A change in input (cam shaft position) causes a deflection of the
range spring via the cam linkage. The resulting force imbalance
between the signal diaphragm assembly and the range spring
causes a change in the 02 output that is fed back to the signal diaphragm
assembly.
The signal diaphragm assembly now acts as a feedback element
by opposing the input force from the range spring. When the force
from the 02 pressure in the signal diaphragm assembly equals the
new range spring force, the output stabilizes and represents the
desired function of the input position.
INTRODUCTION
D - 1