For most people doing jobs that require significant industrial and technical knowledge, the line between instrumentation and control can be blurred. After all, several aspects of one may require another. Indeed, the two disciplines are often considered as one because of how intertwined they can be. Knowing how these disciplines overlap is crucial, especially if, for example, you want to find the leading control instruments experts in your area.
Instrumentation refers to the techniques used to gather valuable data. Control, also known as control engineering, is how the tools of instrumentation are combined with specific expertise to automate processes. Usually, most of the automated processes are in industrial settings, gas controllers.
Instrumentation entails the devices needed to gather the variables like temperature, air pressure, humidity, etc. Control helps in the utilization of such devices to produce industrial automation.
It’s crucial to remember that considering these two disciplines as separate entities can create the impression that they are completely independent of one another. Instrumentation and control go hand-in-hand. The tools of instrumentation are essential for enabling the control of many processes, whether industrial or otherwise. Similarly, instrumentation on its own would not be of much use without expertise in the discipline of control engineering. The two must dovetail to produce automation.
Industrial Instrumentation
Industrial instrumentation involves measuring certain parameters using specific instruments. This is a prime example of how instrumentation and control can be inextricably linked. Any control of any variable has to start with its measurement. This is one example in which instrumentation paves the way for control by quantifying that which can be measured. The process of control helps to manipulate the variable to achieve specific results.
A typical scenario combining instrumentation and control is when a specific quantity, like pressure, is measured. The measured pressure value is then transmitted for computation or control purposes. This can be done manually or automatically. In our example, the pressure value can be transmitted automatically using a signal sent by a computer to the controlling device. This controlling device could be a valve that has to open in order to release some of the built-up pressure.
In addition to valves, other common controlling devices are electric motors and heaters.
Microprocessors and a microcontroller are necessary for programmable switching, necessary for making automated processes easier.
Structure of Industrial Applications
Instrumentation comprises two categories, including the output devices and the input ones. Output devices include things like actuators and transmitters while input devices include sensors and transducers.
At a basic level, the input devices bring in the needed values while the output devices provide the control needed to produce the desired outcome. Devices such as relays are considered part of the output section even though they may not enable direct manipulation of the values brought in by the input devices.
The following are the major elements of instrumentation:
1)Sensors
There are several devices that act as sensors, including:
i)Temperature sensors: These function similarly to a thermometer, helping to gauge temperature changes in a particular system or machine. The temperature sensor provides the signal to the controller. This is a perfect example of the synchronization between control and instrumentation.
ii) Pressure sensors: These sensors help to convert pressure readings into electrical signals. They mainly measure liquid or gas pressure.
2) Controllers
These are mechanical systems that were used to implement complex control algorithms. These days, controllers are more electronic, using computer power to perform these complex implementations.
The most commonly used controllers include:
i)Distributed Control System (DCS)
Control in industrial settings may involve a central location or distribution across several others, forming subsystems. Controlling these subsystems requires a DCS at each subsystem location. The DCS helps to automate various processes. A good example is a nuclear power plant management system.
ii) Programmable Logic Controller (PLC)
The PLC is a real-time output system, giving feedback as a response to the input data. This makes adjustment much quicker and more efficient. This digital computer has replaced the general relay systems of years past.
iii) Supervisory Control and Data Acquisition (SCADA)
SCADA makes the control of instruments and hardware at remote locations much easier. Here, the ability to gather information from remote sites is combined with a supervisory system that enables better oversight. This is done by using coded signals over different communication channels.
Instrumentation vs Control?
Regardless of how much you try to think of them separately, instrumentation will always shadow control and vice versa. The capabilities of one complement the other.
