Proportional−Plus−Reset Controller; Adjustments; Adjustment: Set Point; Adjustment: Proportional Band - Fisher C1P Instruction Manual

Instruction Manual
September 2009
CALIBRATION ADJUSTER (KEY 36)
GE28281−B
E1060
Proportional−Plus−Reset Controllers
This section describes the adjustments and
procedures for calibration and startup. The
adjustment locations are shown in figure 7 unless
otherwise specified. All adjustments must be made
with the cover open. When the adjustments and
calibration procedures are complete, close and latch
the cover. To better understand the adjustments and
overall operation of the controller, refer to the
Principle of Operation section in this manual for
proportional−plus−reset controllers. Refer also to the
schematic diagram in figure 13.

Adjustments

Adjustment: Set Point

Adjust the pressure setting knob by turning the knob
clockwise to increase the set point and
counterclockwise to decrease the set point.
Rotate the knob until the indicator points to the
desired set point pressure value. The pressure
setting dial will reflect the desired set point if the
controller is accurately calibrated.
RESET ADJUSTMENT KNOB
ADJUSTER SCREWS (KEY 48)
Figure 7. Proportional−Plus−Reset Controller Adjustment Locations
C1 Controllers and Transmitters
FLAPPER (KEY 40)
NOZZLE (KEY 54)

Adjustment: Proportional Band

To adjust the proportional band, rotate the
proportional band adjustment knob to the desired
value.
The proportional band adjustment determines the
amount of change in controlled pressure required to
cause the control valve to stroke fully. It may be
adjusted from 3 to 100 percent for 0.2 to 1.0 bar (3
to 15 psig) or 6 to 100 percent for 0.4 to 2.0 bar (6 to
30 psig) of the nominal sensing element pressure
rating.

Adjustment: Reset

To adjust reset action turn the knob clockwise to
decrease the minutes per repeat. Turn the knob
counterclockwise to increase the minutes per repeat.
Increasing the minutes per repeat provides a slower
reset action.
The reset adjustment dial is calibrated in minutes per
repeat. By definition, this is the time in minutes
required for the reset action to produce an output
change which is equal to the change produced by
proportional control action. This is in effect, the time
in minutes required for the controller to increase (or
decrease) its output pressure by an amount equal to
a proportional increase (or decrease) caused by a
change in set point or process pressure.
PRESSURE SETTING KNOB
(KEY 58)
PRESSURE SETTING
DIAL (KEY 6)
PROPORTIONAL BAND
ADJUSTMENT KNOB
13