The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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A quantitative PID tuning procedure is a step-by-step approach leading directly to a set of numerical values…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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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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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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The Law of Mass Conservation states that matter can neither be created nor destroyed. The Law of Energy…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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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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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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