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

Abstract

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. INDEX TERMS Ethylene propylene rubber, cables, thermal aging, mechanical aging, life evaluation.

Experimental study on ageing characteristics of electric locomotive ethylene propylene rubber cable under mechanical–thermal combined action

“…L. Lin et al. carried out the combined ageing test of electrothermic and extrusion stress of the high‐voltage EPR cable used in mining, and tested the infrared spectrum, elongation at break and polarisation–depolarisation current of the ageing cable samples, and obtained the ageing mechanism and ageing state evaluation method of the mining cable [14]. V. Placek et al.…”

“…The relevant literature shows that multiple stress factors will reflect synergistic effect in the ageing process of insulating materials [11][12][13], and it is more in line with the actual stress environment of insulation materials in service equipment. L. Lin et al carried out the combined ageing test of electrothermic and extrusion stress of the high-voltage EPR cable used in mining, and tested the infrared spectrum, elongation at break and polarisation-depolarisation current of the ageing cable samples, and obtained the ageing mechanism and ageing state evaluation method of the mining cable [14]. V. Placek et al studied the electrical, dielectric and mechanical properties of EPR/XLPE cables used in nuclear power plants under thermal-radiation-mechanical combined forces [15,16].…”

On the Use of Oxidation Induction Time as a Kinetic Parameter for Condition Monitoring and Lifetime Evaluation under Ionizing Radiation Environments

“…These methods require accelerated aging tests at high temperatures, at which the speed of the oxidative processes is reasonably high for each temperature and stress time, and then the value of the degradation parameter is determined. Arbitrary setting of a limit criterion for the degradation parameter, for example, reaching 50% of the elongation at break, allows for the kinetic treatment of aging data [23,24]. Thus, by representing this time as a function of the inverse of the aging temperature, a straight line will be obtained, which can be extrapolated to lower temperatures specific to material exploitation and the value of the time at which the degradation parameter reaches its minimum value, allowing for the evaluation of the lifetime of the given material.…”

“…Besides the abovementioned problems, methods based on extrapolation could present further disadvantages, such as: (i) the oxidation mechanism is not constant over a wide temperature range [24]; (ii) the results of extrapolations performed over physical transition points (such as melting of crystallinity), as well as accelerated aging experiments at temperatures in the range of these transitions, may be affected by significant errors [24], as the oxidation mechanism changes as crystalline domains are formed and grow with decreased temperature; (iii) the occurrence of limited oxygen diffusion processes, which can result in significant deviations from the Arrhenius-type dependence [25].…”

Dielectric Loss of EPDM Insulation Subjected to Thermal Stress and Pressure

“…To achieve net-zero carbon emissions by 2050, it is necessary to reduce the use of fossil energy, such as fuel oil, etc., which derives new energy vehicles such as all-electric aircraft, electric ships and electric vehicles with rubber wheels, etc [1]- [3]. Ethylene propylene diene monomer (EPDM) -insulated cables is key components of the power supply in their hybrid power systems, as they are characterized with excellent moisture resistance, thermal resistance, and oxidation resistance [4]- [6]. However, the EPDM-insulated cables in the mining electric vehicle or electrical equipment are usually subjected to the multiphysics field, i.e.…”