极寒地区变压器密封圈的失效分析

Analysis on Failure Mechanism of Transformer Sealing Ring in Extremely Cold Area

为了研究低温环境下变压器密封圈的失效机理,收集了极寒地区变压器中失效的橡胶密封圈试样,并进行了微观结构和力学性能研究:利用扫描电子显微镜表征由于低温和机械应力共同作用导致的微观形貌变化,利用傅里叶变换红外光谱和差示扫描量热仪表征橡胶试样分子链结构和热运动的变化,通过无损微米压痕测试表征橡胶试样微米压痕硬度和简约杨氏模量的变化。结果表明:由于低温、绝缘油和机械压力的长期共同作用,丁腈橡胶(NBR)的分子链结构和排布均发生了变化,导致橡胶的微米压痕硬度和简约杨氏模量下降明显,密封作用丧失。

In order to study the failure mechanism of transformer sealing ring in low temperature environment, we collected some failed rubber sealing rings of transformers in extremely cold area, and studied their microstructure and mechanical properties. The changes of micro morphology caused by low temperature and mechanical stress were characterized by scanning electron microscope, the changes of molecular chain structure and thermal motion of rubber samples were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry, and the changes of micro indentation hardness and reduced Young’s modulus of rubber samples were characterized by non-destructive micron indentation test. The results show that due to the long-term joint action of low temperature, insulating oil, and mechanical stress, both the structure and arrangement of the molecular chain in nitrile butadiene rubber(NBR) have changed, resulting in the obvious decrease of micro indentation hardness and reduced Young’s modulus of the rubber, and the sealing effect loses.