An equivalent circuit model of capacitor voltage transformer(CVT) and its system is established.Taking a 35 kV CVT for example
the causes of the over current on the primary side of CVT are analyzed.The Bode-diagram of CVT and its system is derived to reflect the distribution of resonance points.According to the magnetization curve of nonlinear inductor of CVT’s intermediate transformer and quick saturation damper
a simulation model is derived by the corresponding voltage-ampere characteristics.ATP-EMTP electromagnetic transient simulation software is used to verify the causes of over current on the primary side of the CVT.Results prove that the inrush current on the high voltage side of CVT
the internal series resonance
and the system resonance of the CVT are three major causes leading to over-current on the high voltage side of CVT.Some suggestions of CVT design are also offered.