New algorithms to test distance relays

The type of tests applied to distance protective relays should depend on the type of test required, as well as the type of relay under test. This paper compares the well-known shot as well as search test with the new check test. The check test always forms a good test to test all electromechanical, static and numerical relays during a routine maintenance or commissioning tests. For special fault investigations, type testing and special audits a combination of the shot, search and check test might be required, depending on the focus of the investigation