Detection of insulator ageing

Various tests were performed on glass cap insulators under laboratory conditions. Laboratory methods were selected for a systematic insulator diagnosis on porcelain cap and long rod insulators. Electromechanical parameters of the aged insulators may be reduced to half the original value, to far below the required values. The power frequency wet test proved the ageing for other type of insulator strings too. The monitoring of leakage current impulses helps to follow the procedure. The selection of these impulses detects the mechanical defects of the insulators.