Because the actual usage in addition to the temperature, humidity and tension electric and one of the factors which may affect the occurrence of traces of burns on skin insulation and durability of insulation.
Due to the fact the temperature and stress field, there are certain factors which may affect the burn marks on the surface of the insulation, insulation and durability.
Due to practical use in addition to temperature, moisture content and stress field are also another one of factors which may affect traces burnt on the skin insulation and durability of the insulation.