Tailoring charge transport in epoxy based composite under temperature gradient using K₂Ti₆O₁₃ and asbestine whiskers

Abstract

The solid-gas interface flashover performance of insulators under dc is influenced to a considerable extent by the residual charge effect. The investigation of the charge origin and charge transport in dielectric materials is a significant topic. In this work, the Al 2 O 3 -filled epoxy resin composite was manufactured as the basic dielectric composite. To investigate the charge transport behavior and restrain the charge injection under the temperature gradient, asbestine and K 2 Ti 6 O 13 whiskers were doped into the basic matrix and post type model insulators were prepared. Experimental results demonstrate that the introduction of K 2 Ti 6 O 13 whiskers can effectively restrain heat propagation due to its excellent thermal barrier property, which can restrain the charge transport under temperature gradient to some extent. The charge injection level increases for insulator doped with asbestine whisker, which is due to the introduction of large amounts of shallow traps with trap level density ranging from 0.75-0.91 eV. This work is helpful to understand DC charge transport behavior under temperature gradient and provides important significance in design of a suitable insulator inside HVDC GIL.

Full life property of surface charge accumulation on HVDC spacers considering transient and steady states

“…This indicates that when the conductivity is greater than a certain degree, the effect of the increase in conductivity on the steady-state electric field strength will be very small. However, it is worth noting that the temperature gradient in the spacer is existed, and the temperature is an important factor affecting the conductivity of the spacer [17,18]. The discussion of surface charge accumulation referring to volume conductivity should not be done without considering temperature gradients.…”

“…In addition, a charge adaptive spacer can also be used in this case [3]. The spacer with continuous change of conductivity can also be obtained by 3D printing and FGM technology, thereby reducing the influence of the surface charge change of the spacer on the electric field distortion under the temperature gradient [17]. However, all of the above are performance studies using small samples in the laboratory.…”

Surface flashover in 50 years: Theoretical models and competing mechanisms

“…In region II, surface flashover exhibits a negative dependence on the energy depth of traps but depends positively on the density of shallow surface traps and surface conductivity. The surface modification methods in region II includes fluorination [143][144][145][146]176], plasma deposition [150-153, 168, 177], non-linear conductive material coating [138,139,141,154,155], ozone treatment [148,149], (III) Region dominated by leakage current. When surface conductivity exceeds a critical value, the leakage current through the surface increases rapidly, which degrades the insulation properties of materials and decreases surface flashover voltage.…”

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

“…Li et al [90,91] deposited Cr 2 O 3 on the epoxy surface, found that deep traps were introduced and surface charge injection from the elec- trode was inhibited. He et al [92] focused on restraining the charge transport inside the bulk by doping K 2 Ti 6 O 13 whiskers into epoxybased material.…”