The impact analysis of current transformer´s saturation to relay protection

This paper gives a full elaboration to the types and fundamentals of the current transformer´s saturation, whose impact to all kinds of relay protection device has also been analyzed. Furthermore, an example of a high voltage line´s over-grade tripping failure in a substation, which was caused by current transformer´s saturation, is dissected. The research of the impact analysis will offer some basis for correctly judging, finding and settling the above mentioned failure in the future.