Static electrification phenomena on dielectric materials of SF_6 Gas-insulated transformer

摘要

In Japan, large-capacity gas-insulated transformers (275kV, 300 MVA) designed to be cooled by flowing SF_6 gas have been developed and are operating in underground substations. They use insulating plasticswith excellent heat resistace and insulation strength, in addition to cellulsoe materials such as insulation paper and pressboard used in conventional oil-immersed transformers. Such insulating plastics have a high surface resistance and can be electrified through contact with each other, delamination,or friction.Again, the resistivity of SF_6 gas is so high that once the insulation material surface is electrified, charges are slow to leak out.