NERC/FERC requirements impact on testing philosophy and reliability — Good or bad?

This paper reviews past and present NERC/FERC requirements for relay testing of grid connected protection systems in the US/Canada with a focus on the final draft of PRC-005-2. It will attempt to clarify core requirements that are changing past testing philosophies and address practical testing methods for legacy relays and newer multifunctional digital relays. During the past decade, protective relays have made tremendous advancements in technology; however, many technicians and relay engineers remain confused as to the philosophy, focus, and techniques needed to effectively test these devices without compromising the commissioned status. This paper further clarifies the differences in the philosophical and practical testing of electromechanical, static design, single phase vs. multiphase, microprocessor-based, and modern multifunctional digital relays. It will also discuss some appropriate techniques, and present methods to avoid in the testing process. It will discuss the pitfalls associated with changing relay settings during the testing process, what relay self-diagnostics really means, and provide suggestions to typical mistakes. A comparison between testing protective relay elements as opposed to associated logic functions and schemes is evaluated. Many test procedures provided by relay manufactures are written for manual or entry level functional testing and can lead to undesired operations and reliability issues.