热老化对变压器绝缘垫块微观结构的影响

Effect of Thermal Aging on Microstructure of Transformer Insulating Cushion Block

为研究热老化对变压器绝缘垫块机械性能的影响,采用人工加速热老化与自然老化对比试验研究了热老化对绝缘垫块微观性能、弹性模量的影响机理,并分析了加速热老化与自然老化的等价性。红外光谱结果显示有新的官能团在纤维素的老化过程中产生,长链分子结构被破坏,化学稳定性下降。由扫描电镜图可知,老化破坏了纤维素初始紧密有序的分子排列,使其细胞壁厚度降低,纤维素长度由40μm下降至18μm;弹性模量随老化程度的加深由330 MPa下降至42.1 MPa。表明随老化时间增加,绝缘垫块机械性能降低,热老化是垫块老化的重要因素。自然老化和加速热老化对比试验结果表明两种老化方式对垫块微观性能的影响机理一致,加速热老化数据可靠,可用人工加速热老化模拟自然老化。该结果可为进一步研究绝缘垫块机械性能与变压器轴向预紧力的关系提供参考。

In order to study the influence of thermal aging on the mechanical properties of the insulation cushion block of transformers, we studied the influential mechanism of thermal aging on the micro properties and elastic modulus of the insulation cushion block by artificial accelerated thermal aging and natural aging, and analyzed the equivalence between the accelerated thermal aging and natural aging. Infrared spectroscopy results show that the new functional groups are produced in the aging process of cellulose. The long chain molecular structure is destroyed, and the chemical stability is decreased. The scanning electron microscope shows that the aging damages the initial molecular arrangement of cellulose, the cell wall thickness decreases, the length of cellulose decreases from 40 μm to 18 μm, and the modulus of elasticity decreases from 330 MPa to 42.1 MPa with the increase of aging degree. The results from natural aging and accelerated thermal aging tests show that the effect of the two aging methods on the microstructure of the cushion block is consistent, the accelerated thermal aging data are reliable, so artificial accelerated thermal aging can be used to simulate the natural aging. The results can provide references for further researching the relationship between the mechanical properties of the insulation cushion block and the axial preload of the transformer.