Commissioning numerical relays

Modern numerical relays have many new features that were not available in electromechanical or analog designs. These new features include setting groups, programmable logic and adaptive schemes. Although features make numerical relays very powerful, they also create a need for reviewing commissioning methods. Although there are several references regarding commissioning of electromechanical relays, there are no written standards that address the testing and commissioning of multifunction, numerical protective relays. Therefore, most methods employed today are based on experience. This paper suggests changes to commissioning tests and revised documentation of relay settings. There are many methods that give good results. This paper suggests one approach.