As important power cables for the mining mobile equipment, such as mining shearers, ethylene propylene rubber (EPR) cables often suffer from the combining effect of various stresses on site. In order to evaluate the aging state of EPR insulation, the paper carried out the multi-stress accelerated aging test on the insulation of coal mining flexible EPR cables. The infrared spectrum, elongation at break and polarization and depolarization current of cable insulation samples were measured. The insulation state of EPR cable was evaluated by using the aging factor obtained from isothermal relaxation current. Based on the failure standard of 50% elongation at break, the life formula of EPR insulation was deduced. The experimental and analytical results show that the tiny air gap was torn to the larger air gap under the mechanical stress, which leads to the increase of oxygen infiltration and promotes the thermo-oxygen reaction. The fracture energy of EPR decreases, and mechanical aging is accelerated. Aging factor and elongation at break can indicates the deterioration degree of EPR insulation. Based on the least square method and Arrhenius equation, the service life of the insulation of coal mining flexible EPR cables is deduced.

中文翻译：

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多应力下煤矿用EPR柔性电缆老化寿命评价

乙丙橡胶（EPR）电缆作为采煤机等采矿移动设备的重要电力电缆，在现场经常受到各种应力的综合作用。为了评价EPR绝缘的老化状态，本文对煤矿用EPR柔性电缆的绝缘进行了多应力加速老化试验。测量了电缆绝缘样品的红外光谱、断裂伸长率和极化和去极化电流。EPR电缆的绝缘状态通过等温松弛电流得到的老化因子进行评价。根据断裂伸长率为50%的失效标准，推导出EPR绝缘的寿命公式。实验和分析结果表明，微小的气隙在机械应力作用下被撕裂成较大的气隙，这导致氧气渗透增加并促进热-氧反应。EPR的断裂能降低，机械老化加速。老化系数和断裂伸长率可以指示EPR绝缘的劣化程度。基于最小二乘法和Arrhenius方程，推导了煤矿用EPR柔性电缆绝缘的使用寿命。