Effect of thermal ageing on space charge in ethylene propylene rubber at DC voltage

Abstract

To understand the space charge characteristics of ethylene propylene rubber (EPR) used in MV/HV power cables under thermal stress, the space charge profile is measured by the pulsed electro-acoustic method under 20 kV/mm at 120 and 160 °C. The complex permittivity and physicochemical properties at the different ageing stages are measured and analyzed for an understanding of the effects of thermal ageing on space charge characteristics. The trap properties of EPR during thermal ageing is calculated and analyzed based on the space charge decay model. The results show that both the ageing time and temperature can affect the space charge characteristics of EPR. The space charge characteristics of EPR can be ascribed to the trapping sites caused by the complex chemical and physical structures during thermal ageing. Under the thermal oxygen process, the polar groups and ions increase because of the EPR molecular chain breakages, and the charge injection from the electrodes increases. Based on the decay model of space charge and isothermal decay current theory, the distribution of trap levels in EPR at different ageing stages is obtained. The trap distribution under different ageing process can be explained by the theory of trap filling.

Influence of surface discharge on the deterioration characteristics of ethylene‐propylene rubber cable insulation under alternating current high voltage

“…Scholars from Taiyuan University of Technology have studied the surface discharge characteristics of EPR materials and the surface discharge characteristics of air gap defects. The results show that charge injection and extraction under alternating current (AC) voltage will seriously corrode the material surface and accelerate its degradation process [8, 9]. Scholars from Dalian University of Technology researched the insulation characteristics of EPR by using the Arrhenius curve and evaluated the residual life of EPR and other materials after accelerated thermal aging [10, 11].…”

“…Since ethylene-propylene rubber was first used as cable insulation material in 1962, many scholars have carried out relevant research on dielectric properties [3][4][5], surface discharge characteristics of internal defects [6][7][8][9] and surface discharge properties [10,11] of EPR type cable insulation, and many valuable research results have been obtained. Scholars from Bologna University in Italy studied the aging characteristics of EPR insulation under thermal aging and electrical stress and established a life evaluation model of ethylene propylene rubber based on Weibull distribution and power law [5].…”

Description of space charge transport in oil‐paper insulation using adaptive time‐stepping transient upstream finite element method

“…The accumulation and transport of space charges can cause the degradation or even breakdown of the oil–paper insulation. Many of methods for measuring space charge in dielectric materials have been proposed so far, such as the pulsed electro‐acoustic (PEA), pressure wave propagation (PWP) [1, 2], etc. Meanwhile, the numeric calculation technique, as an important auxiliary technique of the experiment method, has been used for improving the optimal design of electrical insulation in computational high‐voltage engineering.…”

“…The accumulation and transport of space charges can cause the degradation or even breakdown of the oil-paper insulation. Many of methods for measuring space charge in dielectric materials have been proposed so far, such as the pulsed electroacoustic (PEA), pressure wave propagation (PWP) [1,2], etc.…”

Significant enhancement in the electrical conductance properties of ethylene propylene diene monomer using the nano‐SiO 2 particles

“…Ethylene propylene diene monomer (EPDM), a type of the ethylene propylene elastomer, has been widely used as insulation materials in power equipment such as cables and insulators [1,2]. In the cable system, the non-uniform electric field distribution in terminals or joints can trigger partial discharge which deteriorates the insulation and results in failures [3].…”