Design and Test of Contactless Overvoltage Sensor With Spherical Six-Electrode

Most of the available overvoltage sensors are too sensitive to the installation angle and inducing direction. Even a slight angular deflection will cause a nonnegligible error to the measurement. To reduce the impact caused by angular deflection, in this article, we propose a new spherical six-electrode overvoltage sensor to improve the measuring accuracy and stability. First, we presented the 3-D electric field (E-field) coupling mechanism, vector synthesis method, design, and output properties of the proposed sensor. Second, we obtained the relationship between the structural parameters and the equivalent capacitance by the finite-element method (FEM). Finally, we completed the steady-state test, transient test, and 3-D angular deflection test. From the results, the sensor has a broad bandwidth of 1.2 MHz, a phase error of less than 1.8 degrees, and good linearity of the output signals. In the case of 3-D angular deviations, the mean relative error (MRE) of the sensor is lower than 2.55%, with a maximum standard deviation (SD) of 0.088%, which proves that the output of the proposed sensor is well consistent with the overvoltage signal, and its accuracy is almost immune to the angular deflection.