The Impact of the Application of Vacuum Switchgear at Transmission Voltages

High-voltage vacuum switchgear is already in use at present, mostly in Japan, where one utility (of 10) has applied 72/84 kV switchgear for general purposes, in total over 2600 units in transmission systems. In principle, vacuum switchgear for voltages above 52 kV is upgraded from the vacuum technology applied at distribution voltages. Up to and including 145 kV, it seems that vacuum can be a viable alternative to SF6 switchgear. Users see a major benefit in the absence of the greenhouse gas SF6. Several challenges have to be met, especially in the field of reactive load switching. For the EHV and UHV levels, SF6 remains a superior and indispensable extinction medium in the foreseeable future.