抄録
In the past, a current transformation ratio of a current transformer (CT) has been different for each facility corresponding with a rated current of a primary circuit in high voltage (6kV) equipments. By unifying specifications of a CT, there is no need to prepare a CT with various ratings corresponding with a capacity of a load facility, it becomes easier for consumers to modify facilities, and for manufacturers, it enables to standardize of a design and shorten a production period. Recently, it has been popular composition of a secondary circuit of a CT being connected with a digital protection relay bundled with protection and measurement functions not being connected with relays, meters and transducers separately. Because the composition enables to reduce a burden of a secondary circuit of a CT, reduction in size and weight of a CT is achieved and it also contributes to reduce a size of a cubicle and improve a mounting efficiency of a panel. We have developed a CT corresponding with a multi range input (a multi-range CT) and a digital protection relay utilizing its advantages which enable to standardize of a facility design and reduce a size of a cubicle, and report them in this paper.
