Fault in Fenno-Skan 1 repaired and connection back in operation

The voltage transformer fault in the Fenno-Skan 1 high-voltage direct current (HVDC) connection between Finland and Sweden has been corrected, and the connection is back in operation.

The Fenno-Skan 1 transmission connection tripped from the grid on 12 July 2012 at 15.52 as a result of an explosion in a voltage transformer at the Rauma substation in Finland.

Before the disturbance, the transmission capacity of Fenno-Skan 1 was 500 megawatts from Sweden to Finland. After the failure, some of the power was transmitted on the Fenno-Skan 2 HVDC connection and some on the alternating current connections in the north. Up-regulation was activated in the balancing power market in order to control the transmissions.

The disturbance caused a voltage reduction in South-Western Finland. The voltage reduction resulted in process interruptions in manufacturing industries in the region.

There were no people at the Rauma substation when the explosion happened, which is why no personal injuries were caused. The broken voltage transformer will be replaced by a new one, and it will also be ensured that there was no other damage at the substation.

Further information:
Jonne Jäppinen, tel. +358 (0)30 395 422