Azbil Corporation
Model
KFPA
, KFT - Field Mount type Pressure Indicating Controllers
5
2: Indicating controller section
2-1: General
The free end of the sensor element is displaced in proportion to the measured process
value. The displacement is fed through a linkage to the deviation generating
mechanism which magnifies and indicates the deviation on the scale. At the same
time, through another linkage, the control deviation amount is fed to the controller unit
which performs the proportional, reset and rate actions on the deviation amount in
order to produce a pneumatic control output signal.
2-2: Descriptions of mechanisms
2-2-1: Deviation generating mechanism
The deviation generating mechanism consists of a deviation detecting section and an
indicator section. It detects the deviation of the measured value of the process variable
(PV value indicated by the measuring pointer on the scale) from the set point value
(SP value indicated by the set point pointer) and controls the position of the flapper
with respect to the nozzle via a control link.
Figure 1
Figure 2
Deviation
Deviation link
Set point pointer
(green)
Measuring pointer (red)
Link
