The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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In order for any PID controller to be practical, it must be able to do more than just implement the PID…
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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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Feedback obtained from industrial users of FF reveal a common pattern: Fieldbus is a powerful and reliable…
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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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There are multiple motives for compromising the security of an industrial control system, some of which…
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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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The dispersion of visible light into its constituent colors goes all the way back to the 17th century with…
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A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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Calculus. Few areas of mathematics are as powerfully useful in describing and analyzing the physical…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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PID control can be a confusing concept to understand. Here, a brief summary of each term within PID (P. I, and…
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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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A positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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