Anti-Reset Windup (Suffix Letter F) Operation - Fisher 4195 KB Series Instruction Manual

SET POINT
INDICATOR
PROCESS POINTER
REMOTE SET POINT
CONNECTED HERE
INPUT ELEMENT
CONNECTED HERE
CONNECTING
LINK
BEAM
SUPPLY PRESSURE
OUTPUT PRESSURE
NOZZLE PRESSURE
RESET PRESSURE
PROPORTIONAL PRESSURE
46A9764-B
C0593-3 / IL
First, the rate action delays the proportional ac-
tion just long enough to allow the controller to respond
to the change quickly with high gain, but not long
enough for the high gain to cause instability.
Then, the low gain provided by the proportional
action keeps the system stable. Finally, reset action
slowly increases the gain and returns the process
pressure toward the set point.
RESET BELLOWS
PROPORTIONAL
BELLOWS
FLAPPER
NOZZLE
TO
PROPORTIONAL
BELLOWS
DIFFERENTIAL
RELIEF VALVE
Figure 4–6. 4195KC Series Controller Schematic
4195KA, KB, and KC Series
PROPORTIONAL
BAND ADJUSTMENT
SUPPLY
PRESSURE
RATE VALVE
RESET VALVE
TO
RESET
TO-
BELLOWS
NOZZLE
RATE VALVE
RESET VALVE
Anti-Reset Windup (suffix letter F)
Operation
Anti-reset windup is available on all 4195KB and KC
Series controllers and is designated by the letter F in
the type number. The differential relief valve operates
when the difference between the proportional bellows
pressure and the reset bellows pressure reaches a
predetermined value. Anti-reset windup reduces over-
shoot of the process pressure that can result from a
large or prolonged deviation from set point.
REVERSE ACTION
QUANDRANT
FEEDBACK
LINK
FEEDBACK
MOTION
DIRECT ACTION
QUADRANT
INPUT MOTION
OUTPUT PRESSURE
TO FINAL CONTROL
ELEMENT
RELAY
OUTPUT
RELAY
SUPPLY
PRESSURE
FLAPPER
PIVOT
4–11