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# Category Archives for Electrical Basics

## Methods of Applying Relays to Circuit-Breakers from Silent Sentinels 1924

Silent Sentinels 1924 Excerpt #2 This excerpt from the 1924 version of Silent Sentinels discusses how electrical engineers were applying relays to circuit-breakers in 1924.  This is the 2nd in the series.

## 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

## 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

## 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?

## Why did my Frequency Test in Cycles Fail?

We added a new YouTube video, Why did my Frequency Test in Cycles Fail?. This video describes how two different relays with identical settings can have different time test results when performing any frequency

## 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

## 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

## 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

## 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

## Understanding Transformer Vector Groups

Transformer vector groups can be a difficult concept to understand. I was lucky because the transformer ratio test-set I used for the first couple of years in my career allowed me to make three-phase connections,