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Concepts and Laws of Probability

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While the term “probability” may evoke images of…

Teaching Technical Practices (Labwork)

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Labwork is an essential part of any science-based curriculum. Here,…

Analog to Digital Conversion and ADCs

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In order to provide an interface between the internal (digital) world…

VSD and VFD Motor Drive Features

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

The HART Digital/Analog Hybrid Standard

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A technological advance introduced in the late 1980’s was HART,…

Relating 4 to 20 mA Signals to Instrument Variables

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A 4 to 20 mA current signal represents some signal along a 0 to 100…

Feedforward Control

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“Feedforward” is a rather under-used control strategy…

Fiber Optic Data Communication

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Light has long been used as a long-range signaling medium. While…

Introduction to Modbus

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Developed by the Modicon company (the original manufacturer of the…

Logic Programming in PLCs

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Although it seems each model of PLC has its own idiosyncratic standard…

Examples of PLC Systems

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Programmable logic controllers are essentially nothing more than…

Electrical Signal and Control Wiring

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There is much to be said for neatness of assembly in electrical signal…

Common Diagnostic Mistakes in Control Systems

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Volumes could be written about poor diagnostic technique. The…

On/off Electric Motor Control Circuits

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

Safety Instrumented Functions and Systems

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A Safety Instrumented Function, or SIF, is one or more components…

High-reliability Control Systems

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

Limit, Selector, and Override Controls

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Another category of control strategies involves the use of signal…

Valve Positioners

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

Memory Maps and I/O Addressing

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A wise PLC programmer once told me that the first thing any aspiring…

FOUNDATION Fieldbus H1 Protocol Device Configuration and Commissioning

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Fieldbus devices require far more attention in their initial setup and…

Colorimetric and Potentiometric pH Measurement

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pH is the measurement of the hydrogen ion activity in a liquid…

Measuring Electrical Conductivity

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The electrical conductivity of liquids is an important analytical…

Antennas and Resonant Circuits (Tank Circuits)

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Capacitors store energy in electric fields, proportional to the square…

LRV and URV Settings, Digital Trim (Digital Transmitters)

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The advent of “smart” field instruments containing…

Positive Displacement Flowmeters

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A positive displacement flowmeter is a cyclic mechanism built to pass…

Differential Pressure Transmitters

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One of the most common, and most useful, pressure measuring…

On/off Electric Motor Control Circuits

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

Digital Representation of Text

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Binary patterns are not just able to represent numerical values. Given…

Self-balancing Pneumatic Instruments Principles

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A great many precision instruments use the principle of balance to…

Controller Output Current Loops

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

Difference Between Calibration and Re-ranging

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What is Calibration? To calibrate an instrument means to check and…

Instantaneous and Time-overcurrent (50/51) Protection

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Perhaps the most basic and necessary protective relay function is…

Common Control Valve Problems

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Valves can experience a number of problems, most of them either…

Proportional-only Control

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Imagine a liquid-level control system for a vessel, where the position…

Understanding How Three-phase Electric Motors Work

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

Standardized Volumetric Flow

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The majority of flowmeter technologies operate on the principle of…

Introduction to Inductors and Inductance

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Any conductor possesses a characteristic called inductance: the…

FOUNDATION Fieldbus H1 Protocol Device Configuration and Commissioning

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Fieldbus devices require far more attention in their initial setup and…

Human-Machine Interfaces (HMIs)

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Human-machine interfaces, or HMIs, are a critical part of nearly all…

“Normal” status of a Process Switch

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Perhaps the most confusing aspect of discrete sensors is the…

LRV and URV Settings, Digital Trim (Digital Transmitters)

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The advent of “smart” field instruments containing…

Motives for Compromising the Security of an Industrial Control System

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There are multiple motives for compromising the security of an…

Transfer Function Analysis

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An extremely important topic in engineering is that of transfer…

Zero and Span Adjustments (Analog Instruments)

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Linearity of Measurement Instruments The purpose of calibration is to…

Introduction to Optical Analysis

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Light is known to interact with matter in very specific ways, which…

Velocity-based Flowmeters

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The Law of Continuity for fluids states that the product of mass…

Directional Overcurrent (67) Protection

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While 50 and 51 (instantaneous and time overcurrent) relay functions…

FOUNDATION Fieldbus H1 Protocol Data Link Layer

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Like so many other industrial data networks, FOUNDATION Fieldbus is an…

Fluorescence Measurement

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When a high-energy photon strikes an atom, it may eject one of the…

Rotating Phasor in Three-dimensional Form

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The following animation shows a rotating phasor in three-dimensional…

Metering Pumps

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A very common method for directly controlling low flow rates of fluids…

Fiber Optic Data Communication

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Light has long been used as a long-range signaling medium. While…

Dimensional Analysis

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An interesting parallel to the “unity fraction” unit…

Introduction to Capacitors and Capacitance

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Capacitance Any two electrical conductors separated by an insulating…

Pipe and Pipe Fittings

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Pipe is a hollow structure designed to provide an enclosed pathway for…

Control Valve Actuators

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

Resistance, Reactance and Impedance

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Electrical Resistance Resistance (\(R\)) is the dissipative opposition…

Periodic Table of the Ions

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Feedforward Control

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“Feedforward” is a rather under-used control strategy…

Standardized Volumetric Flow

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The majority of flowmeter technologies operate on the principle of…