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, and frustrating when applied to modern digital relays. This post will show you why your traditional tests are probably failing,
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 impedance differential relays are some of the easiest relays to test. Isolate the relay from the
Line distance (21) protection is primarily used to protect transmission lines or other electrical equipment where the equipment’s impedance characteristic can be calculated or modeled with software applications. The protective relay calculates the ratio of measured voltage and current and uses Ohm’s Law to continually monitor the measured impedance while energized. The measured impedance
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 first before we dig deep into the calculations and considerations that explain how high impedance busbar differential schemes function.
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 series explains Line Distance Protection. This bonus animation was created to help relay testers understand distance relay principles. See if you can
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 relays as an example, which may have been a mistake. Let’s take another look at the Directional Overcurrent (67) element from a
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