Catastrophic relay misoperations and successful relay operation

This paper provides detailed technical analysis of several catastrophic relay misoperations and demonstrates how to prevent them from occurring. It also provides an example of using data recorded by a relay during onerous conditions to implement a new protection scheme. Each individual analysis ends with a conclusion which states why the relay misoperated and also provides a recommendation as to the best practice for the particular application. As mistakes often occur at the design stage, it is necessary to carefully assess the initial settings.