Proper testing of protection systems ensures against false tripping and unnecessary outages

This paper discusses the role of three-phase primary injection testing as an important part of the substation commissioning process. Individually testing the components of a protective relay scheme is common practice. Many times, this testing is performed without looking at how the equipment under test interacts with all the other components of the protective relay scheme. Several relay misoperations can be avoided by executing an overall testing plan with all the interconnected components. Three-phase primary current injection tests can be easily performed during equipment commissioning and can detect mistakes that would otherwise only be detected when load is available. This paper describes the planning, execution, and analysis of results of three-phase primary injection tests.