Azbil KFDB, User Manual

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Fig. 1-4 (a). Involute Curve Section
Fig. 1-4.
Fig. 1-4 (b). Dash pot Assembly Condition (Torque Tube Type KFLB)
1-6. Indicating Controller Section
1-6-1. General
The pneumatic output pressure of the transmitter section, which represents the process
being measured, is applied to the pneumatic pressure signal receiver unit, thereby causing
displacement of the end of the element. The displacement is fed via the overtravel link to
the deviation generating mechanism which magnifies the displacement to drive the meter
pointer. At the same time, the mechanism provides another deviation signal which is fed to
the controller mechanism which renders proportional, integral and/or derivative actions on its
input signal in order to deliver a pneumatic control output signal.
1-6-2. Deviation Generating Mechanism
The deviation generating mechanism is comprised of a deviation de tecting section and an
indicating section. It detects the deviation of the process variable (PV pointer) from the
setpoint (SP pointer). The detected deviation is fed via the deviation link to the proportional
action unit and changes the positional relationship between the nozzle and the flapper.