Armfield PCT40 - Exercise O - Proportional Temperature Input with Time Proportional Control of Heater

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Exercise O - Proportional temperature input with time
proportional control of heater
Objective
To control the temperature in the process vessel using a time-proportional controller
connected to a temperature sensor, with a heating element raising the temperature of
the fluid within the vessel.
Overview
The control system in this exercise consists of a pressure sensor with an output
proportional to the temperature detected by the sensor. The output is sent to a time
proportional controller which controls the power supply to the heating element. The
time proportioning controller turns the output on and off at intervals. This ratio of time
“on” to time “off” may be set manually, or may be set automatically by the controller
which then varies the ratio according to the difference between the current control
variable and the required Set Point value.
Equipment Required
PCT40 bench with small process vessel containing a heating coil.
Equipment set up
Ensure that the apparatus has been set up according to the Installation section. The
lid with heating coil should be in position on the small process vessel, with the coil
surrounding the heating element. The apparatus should be connected to a suitable
PC with the PCT40 software installed, via the grey USB cable supplied.
Run the PCT40 software. Select ‘Section 5: Temperature Control (direct batch
heating)’.
Select ‘Configure’ from the Sample menu, and set sampling to Automatic at intervals
of 30 seconds, with duration as Continuous.
Fill the small process vessel with water:
Using a length of tubing with a quick release fitting at both ends, connect the PSV to
one of the fittings on the side of the small process vessel. Ensure that the other fitting
on the side of the process vessel is not connected.
Close the drain valve on the process vessel.
In the software, set the PSV to 100% and watch as the small process vessel fills with
water.
Wait until the coil inside the vessel is fully covered with water, then set the PSV to
0%.
Disconnect the tube from the small process vessel then disconnect the other end
from the PSV.
Take a length of tube with a quick release fitting at one end and a Guest push fitting
at the other. Connect one end to the PSV and the other end to the coil inside the
small process vessel (via the push fitting mounted on the lid).