| Power transformer is a very important power supply element in the power system .The accident of the Power transformer will bring up critical effect to the reliable of the power supply and the common circulation of the system. Therefore, it is necessary to install relay protection equipment which possesses good functions and reliable work. The accidents that transformer differential protection out of control occur more than once in recent year. Because of the sympathetic inrush current's characteristics, it hasn't obvious character. The common criterion of excitation surge current can not distinguish. So that, this topic try to sheer sympathetic inrush current base on comparing the power direction of the transformer's both sides with the inner accident and the outer accident of the transformer. |
