A comprehensive approach for numerical relay system evaluation and test

The protection relay should be designed so as to securely function against faults that may occur to various objects of protection (e.g. transmission lines, transformers, and generators). However, due to the wide variety of objects of protection and circumstances of faults, conditions which the protection relay should guarantee correct operation are just too many, thus it is not easy to secure high quality. Moreover, trip conditions and the number of operation display outputs may vary depending on each substation, therefore sufficient verification is required also on the mass-production stage for securing the required high quality. We have successfully realized an advanced production environment by applying the latest computer technology by taking into account the requirements for securing the required protection relay quality. As a major characteristic of this new production environment, a spiral model was introduced. We call this new production environment MELPRO-SAVE. In this paper, we explain the method for achieving the spiral model design environment