<4. Operation>
4-2
IM 02M04B01-01EN
3. Turn PROPORTIONAL BAND adjustment (on
control dial) to 400 or to safe high value.
Turn DERIVATIVE adjustment (if present) to
0.05.
Turn RESET adjustment (if present) to 50 or
safe high value.
4. Open shutoff valves and close bypass valve.
Bypass valve
Control valve
Shutoff valve
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5. Turn set point knob (or adjust remote set point,
if present), so that set point index is at desired
value.
Model MC43-A5N
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Set point index
Measurement pointer
Output gauge
Proportional adjustment
Derivative adjustment
Reset adjustment
Set point knob
6. If controller is not equipped with optional
automatic-manual transfer, proceed to Step 7.
If controller is equipped with transfer, start up in
manual as follows:
a. Move transfer switch to manual (refer to
section 4.1).
b. Turn on 140 kPa air supply.
c. Adjust output with regulator so that
measurement pointer is held as close as
possible to set point index.
d. After measurement has stabilized, move
transfer switch to automatic. Process is now
on automatic control.
7. If controller is not equipped with optional
automatic-manual switch, turn on 140 kPa air
supply.
8. After measurement has stabilized, adjust
proportional band, derivative, and reset controls
(if present) for best process operation (refer to
section 4.3).
CAUTION
To adjust derivative or reset controls for the best
process operation, please use a screwdriver
designed for precision instrument.
4.3 Controller Adjustments
Time
Measurement
A
Proportional band
A: Too wide
B: Too narrow
C: Correct
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C
B
Change in
demand
Effect of Various Proportional Band Settings
Time
Measurement
Z
Reset time
X: Too short
Z: Too long
Y: Correct
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Y
X
Measurement would
stabilize here without reset
Change in
demand
Effect of Various Reset Times
(1) Proportional Controller (Model MC43-A2)
1. With PROPORTIONAL BAND at 400 or at safe
high value, make change in set point. Observe
process and output responses.
2. If cycling does not occur, adjust
PROPORTIONAL BAND to half of previous
value.
3. Repeat Steps 1 and 2 until cycling is observed.
Then increase PROPORTIONAL BAND to
twice its value.
