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Boiler Water Level Control System Example

Boiler Water Level Control System Example

Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…


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Human-Machine Interfaces (HMIs)

Human-Machine Interfaces (HMIs)

Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…


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Design-based Fortifications

Design-based Fortifications

A design-based fortification is one rooted in technical details of system architecture and functionality. Some…


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Legal Code

Legal Code

Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…


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Instruction List (IL) Programming

Instruction List (IL) Programming

(Will be addressed in future versions of this book)


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Introduction to Power System Automation

Introduction to Power System Automation

Those familiar with industrial instrumentation will find much within the electric power industry remarkably…


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Pressure Sensor Accessories

Pressure Sensor Accessories

Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…


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Fiber Optic Data Communication

Fiber Optic Data Communication

Light has long been used as a long-range signaling medium. While communication by light through open air is…


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Motives for Compromising the Security of an Industrial Control System

Motives for Compromising the Security of an Industrial Control System

There are multiple motives for compromising the security of an industrial control system, some of which…


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Temperature Sensor Accessories

Temperature Sensor Accessories

One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…


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Sequential Function Chart (SFC) Programming

Sequential Function Chart (SFC) Programming

(Will be addressed in future versions of this book)


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Safety Instrumented Functions and Systems

Safety Instrumented Functions and Systems

A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…


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Ladder Diagram (LD) Structure Commands

Ladder Diagram (LD) Structure Commands

The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…


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Common Diagnostic Mistakes in Control Systems

Common Diagnostic Mistakes in Control Systems

Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…


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Relay Circuits and Ladder Diagrams

Relay Circuits and Ladder Diagrams

Electromechanical relays may be connected together to perform logic and control functions, acting as logic…


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Examples of PLC Systems

Examples of PLC Systems

Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…


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Differential (87) Current Protection

Differential (87) Current Protection

One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…


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Digital PID Controllers

Digital PID Controllers

The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…


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Electrical Signal and Control Wiring

Electrical Signal and Control Wiring

There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…


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Introduction to Modbus

Introduction to Modbus

Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…


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Vibration Sensors

Vibration Sensors

Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…


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The HART Digital/Analog Hybrid Standard

The HART Digital/Analog Hybrid Standard

A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…


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VSD and VFD Motor Drive Features

VSD and VFD Motor Drive Features

Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…


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Open-ended, Shorted, and Properly Terminated Transmission Lines

Open-ended, Shorted, and Properly Terminated Transmission Lines

Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…


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Teaching Technical Theory

Teaching Technical Theory

Learning is not merely a process of information transfer. It is first and foremost a transformation of…


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Ultrasonic (Sound) Echo Level Measurement

Ultrasonic (Sound) Echo Level Measurement

A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…


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Instrument Identification Tags

Instrument Identification Tags

Up until this point, we have explored various types of instrumentation diagram, each one making reference to…


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Advantages and Disadvantages of Pneumatic Instruments

Advantages and Disadvantages of Pneumatic Instruments

The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…


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Active Reading and Outlining Documentation

Active Reading and Outlining Documentation

Learning from reading printed text is a kind of problem-solving activity it is own right. The problem is how…


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FOUNDATION Fieldbus H1 Protocol Device Configuration and Commissioning

FOUNDATION Fieldbus H1 Protocol Device Configuration and Commissioning

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


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Atomic Theory and Chemical Symbols

Atomic Theory and Chemical Symbols

The three “elementary” particles of matter comprising all atoms are electrons, protons, and…


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Basic Operation of a Gas Chromatograph

Basic Operation of a Gas Chromatograph

This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…


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Diagnosing Feedback Control Problems

Diagnosing Feedback Control Problems

Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…


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Classified Areas and Electrical Safety Measures

Classified Areas and Electrical Safety Measures

Any physical location in an industrial facility harboring the potential of explosion due to the presence of…


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Digital Multimeter (DMM) Tips and Tricks

Digital Multimeter (DMM) Tips and Tricks

The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…


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Temperature Sensor Accessories

Temperature Sensor Accessories

One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…


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Ladder Diagram (LD) Structure Commands

Ladder Diagram (LD) Structure Commands

The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…


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LRV and URV Settings, Digital Trim (Digital Transmitters)

LRV and URV Settings, Digital Trim (Digital Transmitters)

The advent of “smart” field instruments containing microprocessors has been a great advance for…


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Quantitative PID Tuning Procedures

Quantitative PID Tuning Procedures

A quantitative PID tuning procedure is a step-by-step approach leading directly to a set of numerical values…


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Cascade Control

Cascade Control

A simple control system drawn in block diagram form looks like this: Information from the measuring device…


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Rotating Phasor in Three-dimensional Form

Rotating Phasor in Three-dimensional Form

The following animation shows a rotating phasor in three-dimensional form. The phasor rotates in a complex…


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AC Motor Speed Control

AC Motor Speed Control

AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…


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Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)

Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)

At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…


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Null-balance Voltage Measurement

Null-balance Voltage Measurement

A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…


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Advantages and Disadvantages of Pneumatic Instruments

Advantages and Disadvantages of Pneumatic Instruments

The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…


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AC Motor Braking

AC Motor Braking

There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…


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Fluorescence Measurement

Fluorescence Measurement

When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…


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Diagnosing Feedback Control Problems

Diagnosing Feedback Control Problems

Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…


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Vibration Physics

Vibration Physics

One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…


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Sliding-stem Valves

Sliding-stem Valves

A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…


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Calibration Errors and Testing

Calibration Errors and Testing

The efficient identification and correction of instrument calibration errors is an important function for…


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Level Sensor Accessories

Level Sensor Accessories

Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…


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Techniques for Analyzing Control Strategies

Techniques for Analyzing Control Strategies

Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…


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Digital Representation of Numerical Data

Digital Representation of Numerical Data

Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…


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Policy-based Fortifications

Policy-based Fortifications

These fortifications focus on human behavior rather than system design or component selection. In some ways…


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Antennas and Resonant Circuits (Tank Circuits)

Antennas and Resonant Circuits (Tank Circuits)

Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…


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General Problem-solving Techniques

General Problem-solving Techniques

A variety of problem-solving techniques have been presented for students over the years which are all helpful…


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Introduction to Modbus

Introduction to Modbus

Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…


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Understanding How Three-phase Electric Motors Work

Understanding How Three-phase Electric Motors Work

The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…


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Wastewater Disinfection Example

Wastewater Disinfection Example

The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…


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