The Study on a New Method for Measurement of Electric Fast Transient Voltage Based on Electric Induction of Metal Slice

Abstract

Accurate measurement of electric fast transient (EFT) voltage is very important for insulation design and fault analysis of electric apparatus. In this article, a new simple method for EFT voltage measurement is proposed. Based on the linearity between EFT voltage and electric field intensity on the surface of electrode, the principle of the method is introduced and the corresponding equivalent circuit is built. By using finite-element method (FEM), the capacitances are computed and the relationship between output and input voltages is simulated when we apply Laplace transformation. Experiment model with coaxial structure for verification of the proposed method is built. Based on this model, experiment is conducted. According to the equivalent circuit, by using measured voltage, the parameters of capacitances is also calculated, and they are good coincident with those computed by FEM. The calibration for these capacitances is also done, and their validation is further verified. The proposed method can be used to measure very fast transient overvoltage in gas insulated switchgear and transformer or other apparatus. It can also be used in insulation design and fault location for electric apparatus in power system.