Recent trends within insulation systems for transmission and distribution apparatus

High voltage equipment used in the generation and transmission of electric power is continuously being developed in order to reduce production cost, improve efficiency, and more recently to minimize environmental impact. Insulation systems used in such apparatus are most definitely addressed and major changes are being seen. One major step in development has been the introduction of gas-insulated apparatus in recent years. Recently more and more attention is being paid to SF/sub 6/ recycling and reuse, in attempts to reduce the environmental impact. Meanwhile, new gas-mixtures and hybrid insulation, such as gas/polymer insulation systems, are being developed as alternatives. In another even more recent development, the mica/epoxy insulation that has been used in rotating machines and the oil/cellulose based insulation that has been used in transformers for over 100 years is now being replaced by a new concept from ABB using high voltage cable. Two new products have been recently launched: Powerformer/sup TM/, a new generator that can be directly connected to the transmission network and an oil free power transformer, Dryformer/sup TM/.