Armfield PCT40 - Exercise J - Proportional Pressure Input with Time Proportional Controller Using Normally Closed Solenoid Valve

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Exercise J - Proportional pressure input with time
proportional controller using Normally Closed solenoid
valve
Objective
To control the level in the process vessel using a time-proportional controller
connected to a pressure sensor, with a Normally Closed solenoid valve (SOL2)
controlling outflow from the vessel.
Overview
The control system in this exercise consists of a pressure sensor with an output
proportional to the pressure exerted on the sensor. The output is sent to a time
proportional controller which operates an on/off flow switch. 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 large process vessel, inner cylinder and supplied flexible tubing.
Equipment set up
Ensure that the apparatus has been set up according to the Installation section.
Ensure that the inlet connector for the apparatus (on the right of the plinth behind the
pressure regulator) is connected to a suitable mains water supply. Check that the
central cylinder is securely in position inside large process vessel. Using a suitable
length of tubing, connect the self-sealing connection socket on the base of the large
process vessel to the quick release connection on the valve SOL1 at the front right of
the plinth.
The drain valve at the end of the plinth should be directed to a drain and left open.
Solenoid valves 2 and 3 should be connected to a suitable drain using the tubing
supplied. The drain valve in the base of the large process vessel should also be
connected directly to drain using flexible tubing.
Connect the apparatus to a suitable PC on which the software has been installed
using the pale grey USB cable supplied. The flat connector on the cable connects to
the PC, usually via a socket at the back. The other end connects to the socket on the
orange panel on the front of the plinth. Check that the PC is working and switched
on.
Procedure
Switch on mains power to the console.
Run the PCT40 software. Select ‘Section 3: Level Control (outflow)’.
Select ‘Configure’ from the Sample menu, and set sampling to Automatic at intervals
of 10 seconds, with duration as Continuous.