Effect of long‐term fluorination on surface electrical performance of ethylene propylene rubber

Abstract

To investigate the effect of fluorination on surface electrical performance of ethylene propylene rubber (EPR), four pieces of EPR specimens are prepared and fluorinated for different duration ranging from 120 min to 480 min. The surface morphology and element compositions of experimental specimens are tested. The surface potential decay and complex permittivity are measured. The tracking discharge property and the erosion properties after tracking test are investigated. The surface charge transport and electrical property tailoring mechanism are discussed. The results show that when the fluorination duration is from 120 min to 360 min, the surface morphology gradually becomes flat and compact with time, and the surface resistance to electrical tracking is improved. While an excessive fluorination with the duration of 480 min leads to a significant increase in surface conductivity and a weakening in the resistance to electrical tracking, which is mainly due to a change in surface morphology. The recommended fluorination duration for an optimised surface property is between 240 and 360 min for EPR specimen.

Dynamics of surface charge and electric field distributions on basin‐type insulator in GIS/GIL due to voltage polarity reversal

“…The electric field E can be calculated by potential φ : A large number of experimental results indicate that the significant leakage current can be observed on the insulator surface on the condition of HVDC, and its value has a great influence on the surface charge characteristics [19, 33–35]. The surface current J s is closely related to the surface conductivity γ s and the tangential electric field E t on the solid–insulating material surface [36] The surface conductivity γ s has an exponential relationship with the tangential field E t on the insulator surface [36, 37] where γ s0 is the basic conductivity and α is the correlation coefficient between surface conductivity and electric field.…”

Aging Life Evaluation of Coal Mining Flexible EPR Cables Under Multi-Stresses

“…With the increase of aging temperature, carbonyl index gradually increases, which can be explained by the thermal degradation mechanism of EPR. In the process of thermal oxygen degradation, the molecular bond of EPR is broken, and the oxidation reaction leads to the formation of carbonyl group [4], [21]. At the same aging temperature, the carbonyl index of samples subjected to the mechanical stress is higher than that of normal samples.…”

“…Ethylene Propylene Rubber (EPR) is synthesized by ethylene, propylene and non-conjugated dienes. Because of its excellent corona resistance, moisture resistance, corrosion resistance and flexibility [1], [2], EPR has been the unique insulation of high voltage power cables for the coal mine mobile equipment [3], [4]. However, coal mining EPR cables are often subjected to mechanical stress such as extrusion and tensile stresses, as well as thermal stress caused by the frequent start and stop of motors with the heavy load, so EPR insulation is always aged and deteriorated rapidly.…”

High Temperature Insulation Materials for DC Cable Insulation — Part III: Degradation and Surface Breakdown

“…In order to evaluate the reliability of different high temperature insulation materials in harsh operating environments, important aging factors must be studied in complex conditions. These factors mainly include space charge and surface charge transport behaviors [6][7][8], insulation breakdown and surface flashover trigger mechanism [9][10][11][12], insulation aging mechanisms and charge suppression methods [13][14][15][16], etc. However, uncertain factors in complex environments, such as the temperature variation due to the changing of engine output power, the gas pressure changes when aircraft reaches different altitudes, local contamination due to leakage of oil or environmental pollution, directly influence the insulation performance, leading to greatly increased complexity and difficulty for related fundamental and applied researches.…”