Multifactorial accelerated ageing tests of overhead line insulators including a sandblasting stage

Ageing of overhead line insulators is a complex multifactorial process strongly influenced by environmental conditions and service location. In arid and desert regions, wind‑borne sand and dust introduce additional ageing mechanisms that are scarcely represented in conventional laboratory tests. In this work, a 2000 h multifactorial ageing procedure was modified by incorporating a low‑intensity weekly sandblasting stage to represent desert conditions while avoiding unrealistically severe damage. Sand abrasion was applied to part of each insulator to isolate its specific effects. Four composite insulators and one silicone‑coated glass insulator were tested. Initial and final diagnostic tests included dry and wet withstand voltage, dry flashover voltage, hydrophobicity and leakage current monitoring during voltage‑on phases of the cycle. Results revealed notable performance differences among the insulators. The dominant effect in composite samples was a permanent loss of hydrophobicity on the sand‑abraded regions, accompanied by a visible colour change. Optical microscopy indicated embedding of fine sand particles within the silicone surface. Under dry conditions, withstand tests were passed with increases in leakage current. Under wet conditions, the attainment of