Circuit Breakers and Disconnects

Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…

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Ladder Diagram (LD) Programming Contacts and Coils

In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…

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Measuring Electrical Conductivity

The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…

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Physics and Chemistry Terminology and Definitions

Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…

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Teaching Technical Theory

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

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Rotating Magnetic Fields in Three-phase AC Induction Motors

The following animation shows how the “rotating” magnetic field of a three-phase AC induction…

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Analog Signal Conditioning and Referencing

Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…

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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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Digital Representation of Text

Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…

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What is Electrical Power?

Since we often use electricity to convey energy from one location to another, it is important to be able to…

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P, I, and D Responses Graphed

Visualizing the actions of P, I, and D tuning parameters using graphs is extremely useful in predicting the…

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Limit Switches

A limit switch detects the physical motion of an object by direct contact with that object. An example of a…

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Digital PID Controllers

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

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Force-balance Pressure Transmitters

An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…

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FOUNDATION Fieldbus H1 Protocol Physical Layer

Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…

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Radio-energy Pulse in Guided-wave Radar Level Measurement

The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…

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Chemical Reactor Temperature Control Example

Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…

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Zero and Span Adjustments (Analog Instruments)

Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…

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Using Manometers for Measuring Pressure

A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…

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Auxiliary and Lockout (86) Relays

An important type of “accessory” relay, especially for legacy electromechanical protective relays,…

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