Non-conventional current transformers on live tank circuit breakers

Today nonconventional current transformers (NCCTs) have achieved high performances with a very small volume. In addition the digital output complies with the most stringent requirements of protective relays and meters. The designs take into account the harshest environmental conditions of temperature, vibrations and electromagnetic compatibility. A few current transformers of these types are already in service on several networks all over the world as stand alone units. As the energized part of these current transformers are now very small, it is possible to integrate them directly on a live tank circuit breaker (in opposition to a dead tank circuit breaker). By doing this it is possible to limit the number of insulators and the architecture of the substation. On a single chamber live tank circuit breaker, the current transformer can be mounted either on the top of the chamber or between the chamber and column. On a T shaped live tank circuit breaker (2 chambers in series), current transformers are located on the far end of the chamber. This arrangement is electrically equivalent to a dead tank circuit breaker.