Digital bus-zone protection

A numerical bus-zone protection scheme that overcomes the drawbacks of analog units was designed and constructed. Both high- and low-impedance measurement schemes for us protection relays were investigated. For the numerical bus protection designed, low impedance measurement schemes are used. The basic hardware structure used in the digital bus-zone protection scheme and two modes of realizing breaker fail protection are described. Hardware and software self-monitoring, design tests and operational experience, and customer training are briefly discussed.<
>