Circuit-breaker RMU improves MV/LV transformer protection

Traditionally MV/LV transformers have been protected by switch-fuses because of the significant cost differential with respect to withdrawable CBs and relays. The main advantage for using RMU with fixed integral low cost CB is that it allows to have an improved transformer protection at an equivalent lifetime cost, thus making transformer CB protection affordable. Today, over 60% of the SF6 RMUs sold by the author´s company use CB function.