Changing Controller Action; Switching The Auto/Manual Station; Prestartup Checks For 4194A Series Controllers - Fisher 4194B Series Instruction Manual

4194A, B, and C Series
W3439 / IL
Figure 3-2. Changing Controller Action
(4194A Series Controllers)
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 3-2 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.
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.
3–2
Refer to figure 3-1 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 auto/manual switch is in AUTO, adjusting
the loader knob has no effect on the controller output.
When the auto/manual switch is in MANUAL, changing
the set point has no effect on the controller output.
Prestartup Checks for 4194A Series
Controllers
Refer to figure 3-1 for adjustment locations and refer
to figure 5-21 for key number locations.
When performing the checks, open loop conditions
must exist. An open loop exists when the controller
output does not affect the input pressure or other con-
trol signal to the controller.
If the controller has the auto/manual sta-
tion (suffix letter E), be sure the control-
ler is in the automatic mode before per-
forming prestartup checks.
1. Provide a means of measuring the controller output
pressure by connecting the controller output to a pres-
sure gauge. Connect supply pressure to the supply
pressure regulator and be sure it is delivering the
proper supply pressure to the controller. Do not ex-
ceed the normal operating pressure in table 1-4.
2. For a controller with remote set point (suffix letter
M), connect regulated pressure of 3 to 15 psig (0.2 to
1.0 bar) or 6 to 30 psig (0.4 to 2.1 bar) to the remote
set point connection at the top of the controller case.
3. Remove the two machine screws (key 6) and lift off
the proportional band indicator cover (key 36).
4. Adjust the set point a minimum of 20 percent of
input span above the process pointer.
5. Adjust the proportional band for 5 percent DIRECT.
6. If necessary, connect a pressure source to the pro-
cess connection and adjust the process pointer to the
Note