The NSB El 17 is a class of twelve electric locomotives built by Thyssen-Henschel and Norsk Elektrisk & Brown Boveri (NEBB) for the Norwegian State Railways (NSB). The class was built in two batches, the first delivered in 1982 and numbered 2221–2226, and the second delivered in 1987 and numbered 2227–2232. The traction system of the El 17 was based on the DB Class 120 of Germany (BBC, AEG and Siemens) and were among the first in the world to feature three-phase asynchronous motors. The units were ordered to be used on the intercity Bergen, Dovre and Sørland Lines, but were plagued with technical faults (overheating traction equipment, transient voltages, etc.). The unreliability and lack of sufficient power forced NSB to instead use them in the regional Vestfold and Gjøvik Lines. With the delivery of the El 18, the first series was retired or used as shunters. The second series has been used on the Flåm Line since 1998. The locomotives have a maximum power output and a tractive effort, allowing the locomotive to haul a six-car train. They run on a power supply and are capable of operating at . The units have a Bo'Bo' wheel arrangement, have regenerative brakes and weigh . The series was delivered at the same time as the Di 4 and have some similarities with the class. History During the late 1970s, NSB was in need of new rolling stock for their intercity trains. At first electric multiple units were considered, but NSB instead chose to order locomotives and waggons, to have greater operational flexibility. The choice fell on the German DB Class 120, which was the first three-phase asynchronous locomotive in the world in "almost" regular service (prototype 120.0 in test service 1979, the serial version 120.1 from 1986). However, the Norwegian variation was scaled down due to the maximum axle load (, Class 120 has ) and had a lower power output than the Class 120. Because of this, the El 17 is less powerful than its three predecessors, El 14, El 15 and El 16(3.0 MW instead of 4.4 MW). When the order was placed, it was the first Norwegian electric locomotive with the mechanical components built in Germany. At the same time, NSB ordered five six-axle diesel-electric locomotives from Thyssen-Henschel (Mark Di 4), almost the same as the Danish Mark ME 1500. The Di 4/ME 1500 have many similarities to