4195KA, KB, KC, and KS Controllers
Instruction Manual
Form 5207
April 2007
4-12
SET POINT
INDICATOR
PROCESS POINTER
REMOTE SET POINT
CONNECTED HERE
INPUT ELEMENT
CONNECTED HERE
CONNECTING
LINK
BEAM
FLAPPER
NOZZLE
PROPORTIONAL
BELLOWS
RESET BELLOWS
PROPORTIONAL
BAND ADJUSTMENT
SUPPLY
PRESSURE
RELAY
OUTPUT PRESSURE
TO FINAL CONTROL
ELEMENT
REVERSE ACTION
QUADRANT
FLAPPER
PIVOT
FEEDBACK
LINK
FEEDBACK
MOTION
DIRECT ACTION
QUADRANT
INPUT MOTION
FLAPPER DETAIL
SUPPLY PRESSURE
OUTPUT PRESSURE
NOZZLE PRESSURE
RESET PRESSURE
RELAY
TO
NOZZLE
TO
RESET
BELLOWS
TO
PROPORTIONAL
BELLOWS
DIFFERENTIAL
RELIEF VALVE
SUPPLY
PRESSURE
OUTPUT
PROPORTIONAL-PLUS-RESET-PLUS-RATE CONTROL
PROPORTIONAL-PLUS-RESET-PLUS-RATE CONTROL
WITH ANTI-RESET WINDUP
46A9764-B
C0593-3 / IL
PROPORTIONAL PRESSURE
RATE VALVE
RESET VALVE
RATE VALVE
RESET VALVE
Figure 4-6. 4195KC Series Controller Schematic
A 4195KC Series controller also has a rate valve as
shown in figures 4-6 and 4-7. This valve is an
adjustable restriction that momentarily increases the
controller gain to accelerate the corrective action for
slow pressure systems. A
proportional-plus-reset-plus-rate controller responds
to a change in process pressure as follows:
D First, the rate action delays the proportional
action 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.
D 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.
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