in 1993 the scheme was extended by hvdc skagerrak 3. skagerrak 3 is a monopolar line for a voltage of 350 kv with a capacity of 440 mw at 350 kv. in installing skagerrak 3, the old poles skagerrak 1 and skagerrak 2 were converted to monopolar hvdc schemes, which run with opposite polarity to skagerrak 3.