For a long time, current transformers (CTs) are important components for current measurement and relaying protection in power system. When traditional electromagnetic type CTs are used for measurement and protection, the problems of their magnetic path saturation always disturb people. With the development of the computerized and digital technology of measurement and protections devices, the devices don't match with CTs of big output power. Thus electronic current transformers (ETA) based on Rogowski coil w...