A giant three-limbed transformer has been delivered to the Oskarshamn 2 nuclear power plant in Sweden which is designed to protect the station from solar flares or solar storms, known as geomagnetic induced currents (GIC). Geomagnetic currents can enter power lines and the neutral point of transformers and frequently lead to severely damaged transformers and voltage collapse.
The Oskarshamn 2 plant is frequently subject to blackout-inducing solar flares and the transformer, equipped with three limbs instead of the usual five, is designed to improve reliability by being immune to solar storms.
The three-phase 825 MVA, 420/21 kV generator step-up transformer contains one of the largest and at some 200 tonnes, heaviest, transformer cores that ABB has ever built consisting of 44,000 steel plates 1 m wide and 0.27 mm thick.
In 2003 a GIC tripped several power lines and transformers all over Sweden and caused a blackout affecting 50,000 consumers. A GIC blacked out the entire province of Quebec, Canada, in 1989 costing utilities an estimated at $15.4 million.