Siemens Power Transmission and Distribution (PTD) is replacing a 40-year old high-voltage outdoor switching station (500/220/110 kV) in the Moscow city center with modern, space-saving gas-insulated switchgear (GIS). The order has a value of about €53 million. The customer, the Russian state-owned Federal Grid Company (FGC), Moscow, is taking this step to improve the reliability of the power supply. The first circuit-breakers are due to be switched in before the start of the winter 2007. Coordination of the material deliveries in the center of Moscow will be a logistical tour de force: nine 500-kV switchgear bays, 32 switchgear bays for 220 kV and six 110-kV bays have to be delivered to the right place at the right time.

By converting to gas-insulated technology, grid operator FGC will be able to expand the power supply system in the future to keep pace with the city’s growing energy requirement. The gas-insulated switchgear will be installed on the same site next to the old air-insulated system. The use of GIS technology is essential first because of the restricted space available and second to meet the required short installation times.

Since the 500-kV switchgear bays have to operate within a restricted area, they are equipped with outgoing cable units that enable the existing overhead line feeders to be used via a cable run within the station site. Because an uninterrupted supply of power to the city must be guaranteed while the conversion is in progress, individual switchgear sections will only be disconnected from the power supply system for short periods while the work is being performed.