Tuning; Data Collection - Parr Instrument 4848T Operating Instructions Manual

INSTRUCTIONS FOR THE 4848 T REACTOR CONTROLLER (Continued)

Tuning

The 4848T has a set of default PID values intended
to give reasonable control across a wide range of
conditions, but tighter control can be had by auto-
tuning the system.
To autotune the temperature meter from the main
screen, select the following:
1.
Select the Display Icon in the icon
bar at the top of the screen
2.
Select the Settings Option from
the main display
3.
Select the Display Icon in the icon
bar at the top of the screen
4.
Select the Tuning Option from
the main display to enter the
Temperature Tuning screen
14
The PID settings can be adjusted here manually.
Unless the operator has a background in PID
control, however, autotuning is recommended.
Autotuning is a method to help the controller deter-
mine the best PID settings to control tightly around
the intended setpoint. To do an autotune, fill the
pressure vessel with conditions as equivalent to
the intended process as possible (do a blank run),
and heat it up to the intended setpoint. Once the
temperature has reached setpoint, click on AT to
engage the autotune. During the autotune process,
the temperature will rise by a few degrees, drop
back down to setpoint, and repeat this process
perhaps three times. This can take a good deal of
time, especially in large vessels or in cases at low
temperatures. When the autotune is complete,
the controller will return to regular setpoint mode,
maintain the intended setpoint, and it will have
rewritten the PID values here to better values.
If you need to halt the autotune before completion,
click on the AT button again.

Data Collection

To set the 4848T to collect data, data collection
must first be enabled. Select the Display Icon and
then Data.
1.
Select the Display Icon in the icon
bar at the top of the screen
2.
Select the Data Option from the
main display