the final section from Egersund to Stavanger was not converted until 1956. In 1957, the Kirkenes–Bjørnevatn Line became the only line to remove the electrification and replace the electric locomotives with diesel power. The 1950s saw the electrification of several of regional and commuter lines around Oslo, including the Kongsvinger Line, the Trunk Line and the Dovre Line from Lillestrøm to Hamar, the Vestfold Line and the Eastern Østfold Line. This was largely due to NSB's program to remove all steam locomotives, either by electrification or by dieselization. In the late 1950s and 1960s, several to-be electrified lines were operated with diesel locomotives as an interim solution. The 1960s saw the remaining two stem lines in Southern Norway, the Bergen and Dovre Lines, electrified along with the Gjøvik Line. The Bergen Line was completed in 1964 and the Dovre Line completed in 1970. This finished all the planned electrifications, and the authorities deemed the remaining lines unprofitable to electrify because of low traffic. During the 1990s, a new program was attempted, this time to electrify the entire network, but only the Arendal Line was converted before the program was canceled. However, new lines around Oslo, including the Lieråsen and Oslo Tunnels on the Drammen Line, and the Gardermoen and Asker Lines were electrified at the time they opened. System 15 kV / 16 2/3 Hz - AC-System Norway, like Germany, Austria and Switzerland, uses single phase 15 kV AC railway electrification at 16 2/3 Hz (precisely) for electric train systems. However, there are differences in the supply of power. Nearly all power is derived from rotary converters or static inverters in the substations, which are fed with three-phase AC of 50 Hertz from the public grid. There are only two power stations generating single phase AC. That at Kjofossen, feeds its power directly in the overhead wire, while that at Hakavik supplies a small 55 kV single phase AC network, which feeds five substations. However at two substations, there are also converters. In earlier days, Nygårds Hydroelectric Power Station delivered single phase AC for line between Narvik and Kiruna. The single phase AC line running to Sweden is now used between and as the 15 kV line for feeding the overhead wire. Description From Haugevik Power Plant, two 55 kV long single phase AC powerlines depart, one to Sande and the other to Sundhaugen Switching Station. At Sundhaugen Switching Station,