Multifactor pollution testing to assess the long term performance of composite surge arresters and insulators

Results of continuous salt fog testing at relatively high salinity can be misleading and often relate more to a flashover test rather than to an accelerated ageing test. At high levels of salinity, constantly moving and highly energetic dry band arcs tend to occur away from the surface of the polymer and do not result in the kind of degradation observed from aged devices taken from the distribution network. In some cases, severe accumulation of contaminants can lead to flashover problems, in other cases where environmental conditions are significantly different, tracking and/or erosion damage can rapidly lead to insulation failure in surprisingly few years of service. This paper presents the correlation found between a simple multifactor pollution accelerated ageing test and the degradation observed on aged devices recovered from the network. More importantly, the lack of correlation between continuous salt/fog testing at high salinity and field experience is also presented