process plant with lights on at dawn
Ever wondered what keeps a plant like this running?

Many engineering disciplines

Engineering has SO MANY disciplines, and some are more commonly known than others.  In my experience, if you tell people you are an engineer, they think one of two things:

  • You are either a mechanic or
  • A road and bridge builder/designer

So just to set that misconception to rest: at tertiary level engineering is basically broken down into the following broad disciplines:

  • Electrical and Electronic Engineering
  • Mechanical Engineering
  • Civil Engineering
  • Mechatronic Engineering (a new discipline which focusses on the link between the mechanics and the electronics of systems)

Each of these are further broken down into almost infinite specialisations, especially Electrical and Electronic Engineering.  One such specialisation is Control and Instrumentation (or C&I).

Process Instrumentation

The focus of ‘Process Instrumentation’ (also referred to as Instrument Engineering) is to convert what happens in the physical world into electrical signals (or feedback) which can be interpreted by the system that control the process(es).

Precise information is required for effective control of processes in industrial applications. Effective Control and Instrumentation depend on the accurate extraction of signals that represent parameters from physical systems or processes.

The ultimate control system (Human body):

the human brain radiating sparks

Probably the best example of a complex process control system is the human body.  Information about your surroundings is acquired through the senses such as sight, smell, hearing and touch.

This information is converted into electrical pulses and passed on to the relevant part of the brain through the nervous system.  The brain then interprets these pulses at a phenomenal rate and decide on the next move to make in order to achieve a certain goal or objective.

The brain and how it works in itself is a FASCINATING subject!

NOTE: the term ‘sensor’ is loosely used in this post but it is defined as “the primary element of a measuring chain which converts the input variable into a signal suitable for measurement”.


All branches of engineering depend on measurement.  This includes the measure of pressure, temperature, level (depth/distance), radiation and strain.  In speed and position control systems, feedback from the physical world into electrical signals is of most importance when it comes to high speed production and manufacturing.

This feedback is achieved through various types of measuring devices for various physical variables like pressure, heat, speed and so on.  These devices are grouped under the term ‘instruments’ but are also referred to as sensors, transducers or field devices.

laser light sensor

Definition of a sensor

One definition of a sensor according to is “a mechanical device sensitive to light, temperature, radiation level, or the like, that transmits an electrical signal to a measuring or control instrument” while a transducer is defined as “a device that receives a signal in the form of one type of energy and converts it to a signal in another form”.  A microphone is an example of a transducer that converts acoustic energy into electrical impulses.


Just wanted to get that out there.

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3 thoughts on “Control and Instrument Engineering: what to expect

  1. The human body truly is the ultimate control system. What I always thought was interesting is that not all input from nerves goes to your brain. Reflexes for instance like quickly taking a hand off of a hot burner simply travel up your arm from the nerves that detected the heat. The signal is then rapidly processed by the nerves in your spine and sent back to your muscles to affect a reaction.

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