In substation

the switch operation will cause the fast transient overvoltage and high current including a great deal of high frequency components in the bus bar.In order to predict the current stress in secondary circuits caused by the transient process

the model of current transformer in different wide frequency characteristic is necessary to be set up.In this paper

based on matching vector quantity method

characteristic data of current transformer in wide frequency band is obtained firstly.Then with the transfer function

a synthesis method of two terminal network by means of connecting a resistance at the input terminal is introduced.To verify this method

a model of 500 kV CT in different frequencies has been built.A good simulation result using PsPice has been achieved

and the result shows that the method is accurate.