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On/off Electric Motor Control Circuits

Textbook

An electric motor is often used as a discrete control element in a…

Cascade Control

Textbook

A simple control system drawn in block diagram form looks like this:…

Use of Line Reactors

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Regulating the electric power sent to an electric motor is a task…

DC Motor Speed Control

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DC electric motors generate torque by a reaction between two magnetic…

VSD and VFD Motor Drive Features

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Modern DC and AC motor drives provide features useful when using…

Controller Output Current Loops

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The simplest form of 4-20 mA current loop is the type used to…

Understanding How Three-phase Electric Motors Work

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The key to understanding how three-phase electric motors work is to…

AC Motor Speed Control

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AC induction motors are based on the principle of a rotating magnetic…

AC Motor Braking

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There are several different methods useful for causing an AC induction…

Rotating Magnetic Fields in Three-phase AC Induction Motors

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The following animation shows how the “rotating” magnetic…

AC Motor Braking

Textbook

There are several different methods useful for causing an AC induction…

High-reliability Control Systems

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As discussed at the beginning of this chapter, instrumentation safety…

Valve Positioners

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The reason why a pneumatic control valve’s stem position…

Interposing Relays in PLCs

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In addition to directly performing logic functions, electromechanical…

Controller Output Current Loops

Textbook

The simplest form of 4-20 mA current loop is the type used to…

Analysis of Practical Pneumatic Instruments

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To better understand the design and operation of self-balancing…

Self-regulating, Integrating, and Runaway Process Characteristics

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Perhaps the most important rule of controller tuning is to know the…

Diagnosing Feedback Control Problems

Textbook

Negative feedback systems, in general, tend to cause confusion for…

Ladder Diagram (LD) Programming Contacts and Coils

Textbook

In the United States, the most common language used to program PLCs is…

Cascade Control

Textbook

A simple control system drawn in block diagram form looks like this:…

DC Motor Speed Control

Textbook

DC electric motors generate torque by a reaction between two magnetic…

AC Motor Speed Control

Textbook

AC induction motors are based on the principle of a rotating magnetic…

Digital Representation of Numerical Data

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Process measurements are often of an analog nature: the temperature of…

Ladder Diagram (LD) Structure Commands

Textbook

The simple PLC ladder diagram (LD) commands consist of contacts and…

Non-dispersive Luft Detector Spectroscopy

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Non-dispersive analysis, while newer in discovery than dispersive…

Limit Switches

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A limit switch detects the physical motion of an object by direct…

Non-contact Temperature Sensors

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Virtually any mass above absolute zero temperature emits…

Control Valve Actuators

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The purpose of a control valve actuator is to provide the motive force…

VSD and VFD Motor Drive Features

Textbook

Modern DC and AC motor drives provide features useful when using…

Instantaneous and Time-overcurrent (50/51) Protection

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Perhaps the most basic and necessary protective relay function is…

The Concept of Integration

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Suppose we wished to measure the consumption of propane over time for…

Filled-bulb Temperature Sensors

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Filled-bulb systems exploit the principle of fluid expansion to…

Introduction to Capacitors and Capacitance

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Capacitance Any two electrical conductors separated by an insulating…

Level Gauges (Sightglasses)

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Level gauges are perhaps the simplest indicating instrument for liquid…

Digital PID Controllers

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The vast majority of PID controllers in service today are digital in…

Periodic Table of the Elements

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All substances are comprised of various elements in various…

Basic Components Common to all Radio Systems

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“Radio” systems use electromagnetic fields to communicate…

Numerical Differentiation

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As we have seen, the concept of differentiation is finding the…

Split-range Control

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There are many process control applications in the industry where it…

Common Educational Fallacies

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When I began teaching full-time in 1998, most of what I thought I…

Introduction to Calculus

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Few areas of mathematics are as powerfully useful in describing and…

Instrument and Process Equipment Symbols

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This section shows some of the many instrument symbols found in…

Motives for Compromising the Security of an Industrial Control System

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There are multiple motives for compromising the security of an…

Radiative Temperature Measurement

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Temperature measurement devices may be classified into two broad…

Flow Switches

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A flow switch is one detecting the flow of some fluid through a pipe.…

Safety Gas Analyzers

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Process analyzers measure the concentration of specific substances for…

Proximity Switches

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A proximity switch is one detecting the proximity (closeness) of some…

Scientific System diagnosis and Scientific Reasoning

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At the root of successful system diagnosis is a rigorous adherence to…

Phasor Analysis of Transformer Circuits

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Three-phase AC is the dominant mode of electric power generation and…

Equivalent Series and Parallel Circuits

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Impedance in a series circuit is the orthogonal sum of resistance and…