Instruction Manual
D200156X012
4194HA, HB, HC Controllers
July 2018
34
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 differential pressure toward the set point.
Figure 4‐4. Schematic of Reset‐Rate Option
RELAY OUTPUT
PRESSURE
RATE
VALVE
RESET
VALVE
GAIN
LIMITER
PROPORTIONAL
BELLOWS
RESET
BELLOWS
19A5000-A
A3237-2
Anti‐Reset Windup Option (suffix letter F)
Anti‐reset windup is available for all 4194HB and HC 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 differential
pressure that can result from a large or prolonged deviation from set point such as at process startup.
Remote Set Point Option (suffix letter M)
The capability to adjust the controller set point from a remote location is available for all 4194H controllers. With this
option, 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 adjustment 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.
This option is designated by the suffix letter M in the type number.
Auto/Manual Station Option (suffix letter E)
A controller with the auto/manual option (suffix letter E) has piping on the output side of the relay as shown in figure
4‐5. Supply pressure to the relay is also applied to the manual loader. The manual loader, functioning as a regulator,
