Instruction Manual
D103292X012
C1 Controllers and Transmitters
March 2017
15
Startup: Proportional-Only Controllers (General Tuning Guidelines)
Calibrate the controller prior to this procedure.
1. Be sure that the supply pressure regulator is delivering the proper supply pressure to the controller.
2. Rotate the pressure setting knob to the desired set point.
3. Set the proportional band adjustment to 100 percent for fast processes (example: liquid pressure or liquid flow). For
slow processes (example: temperature), calculate the percentage from the equation below:
For a slow process, determine the initial proportional band setting in percent from the following equation:
2 AllowableOvershoot
PressureSpan
100% + P.B.
For example:
2 0.14bar
2.1bar
100% ^ 13%
2 2psig
30psig
100% ^ 13%
(
)
1.3 proportional band setting
4. Proportional Action
Disturb the system by tapping the flapper lightly or change the set point a small amount and check for system cycling.
If the system does not cycle then lower the proportional band (raising the gain) and disturb the system again.
Continue this procedure until the system cycles. At that point, double the proportional band setting.
Note
Proportional band adjustment affects the set point. Proportional-only controllers will show some offset from set point depending
upon proportional band setting and process demand. After adjusting the proportional band, re-zero by carefully rotating the
nozzle (key 54) until the steady-state process pressure equals the pressure setting dial reading.
This tuning procedure may be too conservative for some systems. The recommended proportional band setting
should be checked for stability by introducing a disturbance and monitoring the process.
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.
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