So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
Textbook
Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
Textbook
The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
Textbook
In a manually-controlled process, a human operator directly actuates some form of final control element…
Textbook
Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
Textbook
A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
Textbook
Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
Textbook
Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
Textbook
The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
Textbook
Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
Textbook
A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
Textbook
A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
Textbook
The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
Textbook
A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
Textbook
One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
Textbook
A form of protection against faults on long-distance power lines is called distance relaying, so named because…
Textbook
In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
Textbook
Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
Textbook
Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
Textbook
There are many process control applications in the industry where it is desirable to have multiple control…
Textbook
As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
Textbook
Constructing PID control systems using discrete components is a fairly simple method involving operational…
Textbook
The transformer is one of the most important components in all of AC circuitry. Principally used to…
Textbook
As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
Textbook
One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
Textbook
A great many chemical composition measurements may be made indirectly by means of electricity, if those…
Textbook
Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
Textbook
Suppose we wished to measure the rate of propane gas flow through a hose to a torch: Flowmeters appropriate…
Textbook
In some process applications, it is important that the control valve be able to completely stop fluid flow…
Textbook
AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
Textbook
The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
Textbook
The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
Textbook
To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…
Textbook
Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
Textbook
A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
Textbook
The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
Textbook
Few areas of mathematics are as powerfully useful in describing and analyzing the physical world as calculus:…
Textbook
Textbook
There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
Textbook
(Will be addressed in future versions of this book)
Textbook
A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
Textbook
Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
Textbook
Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
Textbook
Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
Textbook
Any physical location in an industrial facility harboring the potential of explosion due to the presence of…
Textbook
Another category of control strategies involves the use of signal relays or function blocks with the ability…
Textbook
A variety of problem-solving techniques have been presented for students over the years which are all helpful…
Textbook
The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
Textbook
As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
Textbook
While the term “probability” may evoke images of imprecision, probability is in fact an exact…
Textbook
Visualizing the actions of P, I, and D tuning parameters using graphs is extremely useful in predicting the…
Textbook
This section shows some of the many instrument symbols found in different types of technical diagrams used to…
Textbook
Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
Textbook
In order for any PID controller to be practical, it must be able to do more than just implement the PID…
Textbook
It is often useful to express the amplitude of an alternating quantity such as voltage or current in terms…
Textbook
Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
Textbook
Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
Textbook
Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
Textbook
Feedback obtained from industrial users of FF reveal a common pattern: Fieldbus is a powerful and reliable…
Textbook
In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
Textbook
Facebook
Google
GitHub
Linkedin