A Novel Transient Electric Field Measurement for Low Kerr Constant Liquid Dielectrics Based on Concave Spherical Mirror Conjugate Structure

Abstract

This article proposes a Kerr effect electric field measurement method based on a concave spherical mirror conjugate structure (CSM CS) for a transient electric field in low Kerr constant liquid dielectrics. The accuracy of transient electric field measurement can be greatly improved in a limited space by multiple small-angle reflections. To verify the effect of the proposed structure, the electric field distribution is measured in propylene carbonate (PC) with a high Kerr constant at a switching overvoltage. The measurement results show that the electric field error of a PC under an extremely low electric field is only about 2%. The novel structure improves the electric field measurement accuracy of a liquid with a high Kerr constant. Then, the whole device is applied to the transformer oil, and the accuracy of the measured electric field is also greatly improved. At the same electrode size, the sensitivity of measuring the electric field with the proposed structure is three times that without it. The analysis results show that the introduction of the proposed structure has little effect on the electric field measurement. The proposal and application of the proposed CSM CS further expand the electric field measurement range based on the Kerr effect and improves the electric field measurement accuracy.