Armfield Instruction Manual
118
Temperature Set Point
Investigate the effect of changing the temperature at which the on/off heater switch
operates:
Create a new results sheet by selecting the
icon.
In the software, alter the temperature set point to 50°C.
Select the
icon to begin data logging.
Log the temperature for 15 minutes, then select the
icon to finish data logging.
Repeat the procedure, altering the set point and recording the change in temperature
over time. Suggested values for the temperature set point value are 75 and 90°C, but
more values may be attempted if laboratory time allows. Remember to create a new
results sheet for each set of data.
Return the temperature set point to its original value.
Results
For easy identification or results, it is suggested that each results sheet is renamed
with a descriptive title (e.g. ‘Disturbance’, ‘Set Point’, etc.). The entire workbook
should be saved with a suitable filename for future reference (e.g. PCT40 Exercise
O).
Each set of data should be plotted on a graph of temperature T1 against time.
Make a comparison of each variation in the experimental conditions against the
graph of the initial set of results, noting the difference in response. Compare the
results obtained using time proportioning against those using a simple on/off
controller (as in Exercise N).
For each variation investigated in the experiment, give an example of a comparable
industrial control situation. For each example, consider the suitability of time
proportional control for that particular application.
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