This should be an easy question… A-Phase is shown on this phasor diagram at 0 degrees. What angle would be used to describe B-Phase? Click here to see the correct answer There are three possible correct answers 120° -120° 240° The actual correct answer will depend on the equipment you
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 help you test Breaker Failure Schemes. I highly recommend you read Part 1 of the series first
Did you know that a relay connected to, or set with, the incorrect phase rotation can disable its higher level functions? Did you know that the wrong phase rotation can make your relay testing worthless? Did you know you can quickly and easily tell whether the phase rotation is correct
In-service protective relay meter tests are THE MOST important tests that should be performed on every digital relay. All of your offline relay testing is meaningless if: The CT/PT ratios are incorrect. The relay isn’t connected to its input signals (CTs/PTs). The relay is looking in the wrong direction. The
If you’ve read anything about relay testing written in the last ten years or so, you’ll see a pattern; No-one is talking about the traditional pickup and timing tests most relay testers (and most automated relay testing software) use to test relays. You are much more likely to read terms
Meter tests on protected relays connected to open-delta connected PTs can be very confusing. I know I spent a LOT of time trying to figure out the values reported by my first open-delta connected relay during my first simple meter test. The voltage and current phasors were completely out of
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