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15.1.3 Establish a KP Setting
Use the KP Adjustment Chart to track and log test trials of different controller settings. Make
copies of the adjustment charts, as needed.
u
Go to Main Menu > Unit Status > Heating. Note the temperature here.
u
Go to Main Menu > Control Settings> Heating.
u
Set the KP value at 5.
u
Set the Ti value at 500. This will make the sampling frequency so low that it is essentially of
no consequence and permits adjustment of KP without being affected by Ti.
u
Set the setpoint for 20°F warmer than the current temperature as noted above. (Change the
setpoint last because the controller will immediately respond to the setpoint change, using
the KP and Ti settings that it currently has.)
u
Click the “ENTER” button and then immediately go back to Main Menu > Unit Status >
Heating.
View the Command and Temperature lines on the screen and enter the data at each time
interval that was selected.
When the trial is complete, view the Command line on the chart to see how quickly it ramps up
to 100%. If the Command percentage is rising too slowly, increase the KP value and run the
trial again. The Command percentage should reach 100% (or very nearly) within 2–4 minutes.
Repeat the process, but move the heating setpoint 20°F lower than the current temperature and
change the KP value to a larger value, possibly 10 or 15 larger than the previous trial.
Make data entries on the KP Adjustment Chart (following page) to help track changes to the KP
settings. Select the most appropriate KP setting.
15.1.4 Establish a Ti Setting
u
Leave the KP value as found above.
u
Set the Ti value at the default value of 30. For each trial, increase the Ti setting.
u
Follow the same process as described above. Repeat the trials until the smoothest response
is found that does not cause over-shooting or oscillation of the heating command.
15.1.5 Verify the Combined KP and Ti Settings
When both KP and Ti have been set, run one final trial with the KP and Ti settings at their new
values and record the results in the final chart. This ensures that the results are repeatable.
Temperature and Command readings are obtained from Main Menu > Unit Status > Heating
For Elapsed Time, select a convenient amount of time to allow between readings
(example: 30 seconds).
In the first column of each trial, fill in the starting data for the trial
REFERENCE
