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.