The application of charged detection technology of transformer winding deformation is beneficial to im-prove the safety and reliability of transformer operation

and reduce the economic loss caused by outage mainte-nance. This paper points out the deficiency of the current research on the charged detection of the winding and makesan improvement

and puts forward a new method for the detection of the transformer winding deformation based onthe signal injection using coupling capacitor. In this paper

sweep signal of Tektronix high power signal generator isinjected into transformer through the neutral bushing by using the coupling capacitor

and the ground current of thehigh voltage bushing tap is measured as a response signal. Then

the input signal and response signal are input to theindustrial computer for data processing

and the frequency response curve of the measured winding is obtained. Inthis paper

the circuit simulation model of transformer winding is built

and the feasibility of the proposed method isillustrated by the theory. Finally

a 110 kV real transformer is tested. The test results show that the method has thepotential for practical application.