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All posts by Chris Werstiuk

Can You Predict What Happens in a Permissive Over-Reaching Transfer Trip (POTT) Scheme?

The Relay Testing Handbook: End-to-End Testing covers the most common Communication-Assisted Protection Schemes including the Permissive Over-Reaching Transfer Trip (POTT) Scheme. This bonus animation

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Can You Predict What Happens in a Direct Under-Reaching Transfer Trip (DUTT) Scheme?

The Relay Testing Handbook: End-to-End Testing covers the most common Communication-Assisted Protection Schemes including the Direct Under-Reaching Transfer Trip (DUTT) Scheme. This bonus animation

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Can You Predict What Happens Inside a Distance Protection Relay?

Distance Protection (21) has many names (Line Protection, Line Distance Protection, Impedance Protection) and is one of the more complicated elements used in protective relaying. The Relay Testing Handbook

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Ask Chris: What is the difference between contactors, motor starters, relays and circuit breakers?

A reader submitted a question through the Ask Chris form. I’ve expanded the original question from “what are the differences between relays, contactors and motor starters?” to “What

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Which is the Killer, Current or Voltage?

A friend forwarded me this video because it relates to electricity. It made me laugh. Don’t try this at home. Is it the current or voltage that kills?

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A New Transmission Line Protection (21) Video

End-to-End Testing can appear to be a daunting task. However, any relay tester can perform successful End-to-End Tests with a basic understanding of transmission line protection (or 21 impedance protection)

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Finding the Direction in Directional Overcurrent Relays

A reader recently asked a question about the forward and reverse directions described in the Directional Overcurrent Relay section of The Relay Testing Handbook series.  I used electro-mechanical directional

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Understanding Microprocessor Relay Logic – Microprocessor Relay Testing Plans

We have uploaded our fourth YouTube video, Understanding Microprocessor Relay Logic – Microprocessor Relay Testing Plans. (http://youtu.be/ijdSKozctNo) This video discusses how

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Understanding Microprocessor Relay Logic – Relay Digital Logic Schemes

We have uploaded our third YouTube video, Understanding Microprocessor Relay Logic – Relay Digital Logic Schemes. (http://youtu.be/do3EkEcb0eM) This video discusses the different relay

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Understanding Microprocessor Relay Logic – Basic Digital Logic

We have uploaded our second YouTube video, Understanding Microprocessor Relay Logic – Basic Digital Logic. (http://youtu.be/DEN-ZEtEZ5c) This video discusses how you can convert the digital

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Understanding Microprocessor Relay Logic – A Brief History of Relays

We have uploaded our first YouTube video, Understanding Microprocessor Relay Logic – A Brief History of Relays. (http://youtu.be/q_E_Gv_9_LQ) This video talks about the history of microprocessor

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Good Video for CT / PT / Phasor Diagram / Transformer Connections

Here is another excellent, but dated, video that covers a lot more than its title. It starts with an excellent introduction to CTs and PTs (http://youtu.be/T5U5M3RYx9Q) Then some Phasor Diagram basics

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2014 NETA Powertest Conference

I’ll be presenting “Simplified Motor Relay Testing” at the 2014 NETA Powertest conference in Denver. Here’s an excerpt from the NETA Powertest website Join us at PowerTest 2014

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A Good Resource for Electrical Theory Basics

All high voltage electrical testers should understand the basics of electrical theory. Unfortunately, Many people in the high voltage electrical testing industry fall into testing by accident and never

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Good Video Describing Electrical Fault Calculations

Understanding how to perform electrical fault calculations is not necessary if your primary goal is to simply test relays.  However, if you want to truly understand the electrical systems, how

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