Effective Contaminant Deposit Density-a new concept of the pollution level of composite insulators

Effective Contaminant Deposit Density (ECDD)-a new concept of the pollution level of silicone rubber composite insulators is introduced in this paper to study the transferency of hydrophobicity and the artificial contamination test method of composite insulators. A solid contamination layer method is adopted. The effective contaminant is defined as the dissolved salt from the contamination layer when the polluted sample or insulator is wetted. It is found that the ECDD is much less than the original artificially polluted salt deposit density (SDD). This phenomenon means that only part of the salts could be dissolved out when the polluted silicone rubber sample is wetted. Hence the lower ECDD is also the important reason why the silicone rubber insulator could always keep its excellent pollution performance besides the well-known reason that hydrophobicity caused an uncontinued water film on the insulator surface. Then ECDD or the ratio of ECDD/SDD, called solved ratio, could be used to describe the transferency of hydrophobicite. The lower solved ratio represents the more sufficient transference