Aging of silicone rubber composite insulators on 400 kV transmission lines

Abstract

A number of silicone rubber composite insulators have been examined following 15 years of service on a coastal 400 kV transmission line in the UK. Extensive measurements of their hydrophobicity, as determined by contact angle, are given along with a description of their appearance. The hydrophobicity change varied from the low voltage end to the high voltage end with the lowest contact angles being found in the middle of the string. The sheds also aged differently around their circumference and this was reflected in discoloration differences on different sides of the insulator, in addition to hydrophobicity changes. The greatest change to properties was witnessed on the core of the insulators on which contact angles of less than 70 degrees were recorded.

Real-time monitoring of leakage current on insulating cross-arms in relation to local weather conditions

“…The primary cause of polymeric insulator failure nowadays is surface degradation which is affected by the local environmental conditions [3]. The hydrophobic properties of the material may diminish over time allowing the formation of continuous water paths when the insulator becomes wet [4].…”

A coastal trial facility for high voltage composite cross-arms

“…The ageing process is often accelerated in polluted environments because the hydrophobicity of the material decreases more rapidly. Consequently, the continuous water paths formed on the surface of the insulator allow currents to flow that may result in more intense arcing activity [3]. Hence, leakage current is a good indication on how the electrical performance of the insulator changes over time [4].…”

Effect of artificial aging on polymeric surge arresters and polymer insulators for electricity distribution networks

“…An insulator or surge arrester in such an event is considered as failed and has to be serviced or replaced [9] . This study focuses on the polymers used for manufacturing surge arresters housings and insulators of distribution systems that may already be presenting problems of penetration obtained from samples installed in the field.…”