Review of surface transient charge measurement on solid insulating materials via the Pockels technique

Abstract

Surface charges accumulated on solid insulating materials in electrical apparatuses and electronic devices could distort the initial electric field and severely damage the insulation performance. Accurate transient surface charge measurement is critical to determine the mechanisms of charge transport and flashover occurrence, and estimate surface insulation strength under high voltage. The measurement technique based on the Pockels electro‐optic effect is considered as the only approach for 2‐D dynamic charge distribution behaviour so far, and it has good capability to avoid original electric field distortion caused by conventional methods featured by metal probes. This paper reviews recent progress of the non‐invasive dynamic surface charge measurement systems on the Pockels technique. We focus especially on typical systems with transmitting and reflecting configurations and the frequently used fast inversion algorithms. It can be inferred that higher spatial‐temporal resolution, higher signal‐to‐noise ratio, and better compatibility for both transparent and opaque materials are the future development trends, which greatly depend on multiple technological breakthroughs at impact‐resistant electro‐optic crystals, advanced high‐speed photography and high‐performance inversion algorithms. In addition, the recent studies on transient behaviour of surface discharge, together with the present limitation and future prospects are discussed. It is expected that more ideas will be inspired in transient surface charge measurement by the Pockels technique and other relevant electro‐optic methods.

China's 10-year progress in DC gas-insulated equipment: From basic research to industry perspective

“…Three methods can generally be used to obtain surface charge distribution, e.g., dust figure technique, electrostatic probe, and linear electro-optic method [2,21,22] . Since the third method, also known as Pockels effect, is available only for thin and transparent/translucent insulating material, it is not suitable for the insulators in gas insulated equipment and will not be involved here.…”

Wide Bandgap Nanocoatings for Polymer Dielectric with Outstanding Electrical Strength

“…[ 13–15 ] These charges seriously distort the surface electric field, induce flashover along the surface, and lead to insulation failure. [ 16–18 ]…”

“…[13][14][15] These charges seriously distort the surface electric field, induce flashover along the surface, and lead to insulation failure. [16][17][18] The breakdown strengths of polymer dielectrics are generally improved by doping with nanoparticles. [19][20][21] However, due to the extremely high surface energies of nanoparticles and poor compatibility with organic matrices, it is easy to introduce many defects in the matrix and cause an uneven distribution of the electric field inside the composite dielectric, which results in a decrease in the safety of the nanocomposite dielectric.…”

A low‐cost and high‐performance self‐trigger method for high‐voltage transient measurement

“…Transient measurement is the foundation of clarifying lightning, arc, plasma, and switching operations [1][2][3][4][5]. Appropriate triggering of the acquisition devices is critical to rapidly measure the transient voltages [6][7][8].…”