Study on Aging and Criterion of Sheds and Housing of Silicon Rubber Composite Insulator

The operation condition of composite insulators for AC transmission lines in China is presented,the composite insulators’ ageing and causes of accidents are analyzed.The hardness and hydrophobicity of composite insulators takedown from field are measured and the aging performance of these composite insulators is evaluated.It is revealed that the principal reason of composite insulator damage at present consists in the immaturity of design,manufacturing technology and material composition at the early stage of composite insulator production;and the failures really caused by ageing of silicon rubber sheds and housings are still seldom found.Most of composite insulators,which put into operation more than ten years,still possess good hydrophobicity,and there is not evident relation between the decrease of hydrophobicity and the increase of hardness.The ageing of silicon rubber is a long term process;although the medium-term feature of ageing appears,the secure operation of composite inslators still can be ensured in a longer period,therefore the ageing of silicon rubber should not become the reason to handicap the utilation of composite insulators.