The multi-differential relaying for transformer protection

As the main facility, the transformer plays an important role in the security of power system. The effectiveness of the differential relay used for protecting transformer against internal faults is undisputed. The introduction of microprocessor technology enabled multiple protection relays to be integrated into one protection platform, which has advantages when applied to transformer protection. A scheme for large capability transformer is brought forward in this paper, which applies differential protection principles to cooperate with one another, so that it can make a compromise with operating speed and sensitivity at the same time. This paper also provides an insight into the hardware and industry application experience.