Instruction Manual
D200160X012
4195K Controllers
July 2018
39
A 4195KC 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.
Figure 4‐7. Reset‐Rate Schematic
RELAY OUTPUT
PRESSURE
RATE
VALVE
RESET
VALVE
GAIN
LIMITER
PROPORTIONAL
BELLOWS
RESET
BELLOWS
19A5000-A
A3237‐2
Anti‐Reset Windup (suffix letter F) Operation
Anti‐reset windup is available on all 4195KB and KC 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 overshoot of the process pressure that
can result from a large or prolonged deviation from set point.
Remote Set Point (suffix letter M) Operation
The capability to adjust the controller set point from a remote location is available with all 4195KB and KC controllers.
This option is designated by the letter M in the type number.
A control pressure is applied to the capsular element within the remote set point assembly. The expansion and
contraction of the capsule moves the set point indicator via connecting linkage. Increasing the control pressure to the
capsule increases the set point setting and decreasing the control pressure reduces the set point setting.
