Changing Controller Action; Reset Adjustment; Rate Adjustment; Anti-Reset Windup (Suffix Letter F) Adjustment - Fisher 4194B Series Instruction Manual

4194A, B, and C Series
W3439 / IL
Figure 4-2. Changing Controller Action
(4194B and C Series Controllers)
is marked in percentages of process differential pres-
sure required to drive the controller from zero output to
full output.
To adjust the proportional band, open the controller
cover and locate the proportional band adjustment (PB
ADJ) knob. Rotate the knob until the desired value is
opposite the line on the proportional band indicator
cover.

Changing Controller Action

To change the controller action from direct to reverse
or vice versa, loosen the screws on the proportional
band indicator cover. Lift the cover out as shown in
figure 4-2 and rotate the proportional band adjustment
to the desired action. Setting the proportional band to
the values in the white portion of the adjustment pro-
vides direct controller action; setting proportional band
in the black portion provides reverse controller action.
For direct control action:
An increasing sensed differential pressure increases
output pressure.
For reverse control action:
An increasing sensed differential pressure decreases
output pressure.
After changing the action, tighten the two screws on
the proportional band indicator cover.

Reset Adjustment

To adjust reset, open the controller cover and locate
the RESET adjustment. Rotate the adjustment clock-
wise to decrease the minutes per repeat or counter-
clockwise to increase the minutes per repeat. Increas-
4–2
ing the minutes per repeat provides a slower reset
action.

Rate Adjustment

To adjust rate, open the controller cover and locate the
RATE adjustment. Rotate the adjustment clockwise to
decrease the minutes (less rate action) or counter-
clockwise to increase the minutes (more rate action).
Anti-Reset Windup (suffix letter F)
Adjustment
If the arrow on the differential relief valve points toward
the bottom of the controller case, as shown in figure
4-1, the relief valve opens with increasing controller
output pressure. If the arrow points in the opposite
direction, the relief valve opens with decreasing con-
troller output pressure. Differential relief pressure is
factory set at 5 psig (0.3 bar). Maximum relief pres-
sure is 7 psig (0.5 bar); minimum is 2 psig (0.1 bar).
Turn the adjusting screw counterclockwise to increase
differential relief pressure, clockwise to decrease it.
Switching The Auto/Manual Station (suffix
letter E)
CAUTION
Switching the controller between auto-
matic and manual mode without balanc-
ing can disturb the process and cause
controller cycling.
Refer to figure 4-1 if the controller has the auto/manu-
al station (suffix letter E). To switch from automatic to
manual mode, or from manual to automatic, you must
first balance the manual output with the controller out-
put. Two balance methods are available to equalize
the manual output with the controller output.
To switch from automatic to manual mode, carefully
adjust the loader knob until the metal ball inside the
plastic tube moves into the switching zone. Then
move the automatic/manual switch to MANUAL. Turn
the loader knob clockwise to increase the controller
output or counterclockwise to decrease it.
To switch from manual to automatic mode, adjust the
set point to move the ball into the switching zone. Turn
the switch to AUTO and adjust the set point to control
the output.
When the automatic/manual switch is in AUTO, adjust-
ing the loader knob has no effect on the controller out-
put. When the automatic/manual switch is in MANU-
AL, changing the set point has no effect on the
controller output.