Disconnector failure caused the disturbance in electricity imports from RussiaA disturbance was experienced in electricity imports from Russia into Finland on 14 September at 18 - 23. The disturbance in the Russian power system caused a restriction in Russian imports into Finland, with the biggest restriction being 900 MW.
Based on an account received from the Russian transmission system operator, the cause of the disturbance was a 750 kV disconnector failure at the Kalinin nuclear power station near Moscow, as a result of which the 750 kV trunk line feeding the St Petersburg region from Moscow was disconnected. In order to keep the remaining intact connections within the prescribed limits, the Russian party restricted electricity transmission from Russia to Finland by reducing the power of the Vyborg direct current link from 17.57 Finnish time.
The restoration of the 750 kV connection required the introduction of a parallel disconnector, which was being serviced. Normal electricity transmission was restored on 15 September 2007 at 00.15 Finnish time. Further information:
Timo Kaukonen, Fingrid Oyj, tel. +358 (0)40 545 2124