Relay testing

Posted by Yifan Wang on 20 February, 2022

Testing is always a must-have step for almost any designs to verify the proper functionalities.

Lately I’ve been working on some complex auto-restoration relay settings development. Had so much fun. And due to the complexity of the relay logics, I decided to use one relay in my lab to test out the logics a bit so that an extra level of confidence could be gained.

In the context of power system, relay engineers often do the programing or designs (through vendor specific software) in the intelligent electronic devices which are often called relays (see one below), in a way that’s similar to any other programmers who may write codes in some environment to achieve certain goals. We’d have our INs and our OUTs. And we use the logical thinking to determine the things in the middle.

Back to testing, take SEL relays for example, looking at the SER records (a piece of sample shown below) is one way you could probe into the relay when something was not behaving as expected. It usually contains trips, inits, blocks and equip. status, or any other internal nodes, etc.

It tells you the timing of internal word bit state changes. Just looking at the raw sequence records is bit inconvenient, so how about some visuals then? With a bit of programming, we could see the signals in a hopefully better way. Here’s a screenshot came out from my Python script that can visualize the timing sequences from SER a bit. And if you’re interested in, here’s how you could use it (SER Display)

Hope something that has been useful to me could be useful to you too 😊. “See” you next time.