Category Archives for Relay Elements

How to Test Breaker Failure Schemes

I presented a “Testing Breaker Failure Schemes” paper at the 36th annual Hands-On Relay School in 2019. This post is the second part of the paper that will give step-by-step test plans to

Introduction to Breaker Failure Schemes (50BF)

I presented a “Testing Breaker Failure Schemes” paper at the 36th annual Hands-On Relay School in 2019. Here’s the first part of the paper that will give you a basic introduction to

Why Do Traditional Line Distance Protection Relay Testing Procedures FAIL on Digital Relays?

Traditional line distance relay testing procedures (MTA, Reach, and Timing) are a great way to test electro-mechanical relays and learn how line impedance relays operate; but they are inefficient, ineffective,

High Impedance Busbar Differential Protection

We covered the basic operating principles of high impedance busbar differential protection in our previous post, I Want to Know How a High Impedance Differential Scheme Works. You should read that post

I Want to Know How a High Impedance Differential Scheme Works

We received this question from the Ask Chris form at relaytraining.com. Follow this link to ask your own question and it might appear in a future blog post. High Impedance Differential Scheme Testing High

Understanding Distance Protection (21) Video

The last video in our end-to-end testing series gave you a general overview of distance protection, and why we use it in modern electrical systems. It is important to know how a regular distance protection

Testing Directional Overcurrent Relays

In the previous post about Directional Overcurrent relay (67) testing (Finding the Direction in Directional Overcurrent Relays), we reviewed Directional Overcurrent protection from a system perspective

Can You Predict What Happens in a Directional Comparison Blocking (DCB) Scheme?

The Relay Testing Handbook: End-to-End Testing covers the most common Communication-Assisted Protection Schemes including the Directional Comparison Blocking (DCB) Scheme. This bonus animation shows the

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

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

Can You Predict What Happens in a Directional Comparison Unblocking (DCUB) Scheme?

The Relay Testing Handbook: End-to-End Testing covers the most common Communication-Assisted Protection Schemes including the Directional Comparison Unblocking (DCUB) Scheme. This bonus animation shows

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

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 shows

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

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)

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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