Self screening solid material for transformers - also has mechanical load bearing properties

摘要

A material which may typically be used for screening and separating connections in electrical apparatus, for example oil filled transformers, combines the relatively void free properties of impregnated press phan with the mechanical properties of more solid materials. Typically it may be a glass fibre armoured synthetic resin bonded material, but the essential requirements are given by a formula which relates the conductivity of the solid material, the dielectric constant of the solid material, the dielectric constant of the surrounding medium (for example oil), the effective electrid field strength in the surrounding medium, the field strength in the solid material at which there is no discharge, and the operating frequency. The creep resistance of the material should be better than that of the presspahn, and the modules of elasticity is given. Temperatures over 115 deg. C can be withstood by the material.