Effect of new cleaning solvents on electrical insulation materials

Trichloroethane which was often used to clean high-voltage cables (during installation of joints or terminations), various accessories, generators and motors, now must be replaced by environmentally-friendlier solvents to protect the ozone layer. Among the new solvents considered, di-chloro-fluoro ethanes prove to be the best candidates; terpenes offered a cheaper alternative for some applications. A set of various physical, chemical and electrical tests was designed to assess the compatibility and preservation of long-term electrical performance of insulation materials exposed to the cleaning solvent. Physical testing includes swelling, decoloration and elongation at break measurements. Chemical testing includes volatility and residue analysis; attention was paid to the flash point. Electrical performance was checked using tan δ, resistance to breakdown and tracking tests