Lesson 2 - Principles of Process Control
This lesson explores exactly what process control is and explains why it is important. It examines the various levels within process control systems and identifies the associated equipment. It also takes a detailed look at the various automation communication and control elements.
Instruments
Instruments play an important role in process control and automation.
We cover instruments in greater detail in the Process Instrumentation lesson. Let us now briefly look at some of the functions and components of these instruments.
Some instruments are indicators only. By indicator, we mean that they display information about the process and are readable by a human. Most of these take the format of a gauge, but they can also have a digital readout.
A transmitter converts the measured value from a sensor to a form whereby it can be transmitted and used in another location or by another device.
Standalone recorders were used before databases were the norm. These often took the form of chart recorders.
A controller compares the measurement value to a setpoint and then outputs a value to a control element.
A transducer translates mechanical signals into electrical signals, and this forms part of many instruments.
A converter converts one type of signal into another, such as analogue into pneumatic.