Medium-voltage replacement breaker projects

Many of the medium-voltage (5, 15, and 38 kV) switchgear installations in service today are of the age that makes replacement circuit breakers a cost-effective investment to extend the life of the substation and improve the overall safety. Today's replacement circuit breakers, employing the latest interrupter technology, require less maintenance, and utilize safety features that were not available on equipment designs 30 or 40 years ago. A successful project to install replacement breakers requires an understanding of the following: which IEEE standards apply to the design and testing of replacement breakers; how to determine if a switchgear installation is a good candidate for a replacement breaker project; commissioning activities that are required to assure a safe and successful startup; and impact of the change in technologies on the system reliability. This paper addresses how these topics impact a project to replace earlier vintage circuit breakers to extend the life of the switchgear installation.