Full-safety working: a new trend in the construction of MV/LV transformers

The search for optimum safety in operating MV/LV transformers has led EDF to define objective criteria for resistance to fire and climatic and environmental constraints. This study was particular concerned with dry type transformers. The experimental method proposed allows relatively low cost selection of materials and verification of the overall behaviour of the equipment. The three industrial embodiments described, all of which use different technologies, show the importance which should be attached to the choice of the materials used, and in particular the fire-proofing. It ensures that the equipment will not itself be a source of fire in the event of an internal fault and will make only a slight contribution to an external fire. Moreover, provided that the fire-proofing is not itself a pollutant, it can considerably reduce the formation of breakdown products during a fire