When the Swedish SJ started to electrify many secondary lines in the thirties, they needed powerful electric locomotives with a low axle load. They were not only to be used for passenger and freight trains, but also as a shunter. Features of these locomotives were a centrally mounted cab with pantograph on the roof and sprung traction motors. Anyway, the first variant called Ha built from 1939 did not have satisfying running characteristics and had to be limited to 70 km/h instead of the planned 90 km/h.

In their twelve years of production, different variants were built with incremental improvements. Next after Ha were the Hb and Hc with improvements in design and suspension, which could be approved for 80 km/h. Of the variant Hd, only four were built which had other traction motors and were later rebuilt to the Hg standard. The Hg was the last variant of which 56 were built between 1947 and 1951.

Together with seven Hg built for the TGOJ in 1954, ASEA and Motala Verkstad completed 151 of all variants. To haul heavier freight trains, 36 of the 56 Hg locomotives were equipped with multiple controls between 1972 and 1980. These were designated Hg2. While all locomotives of the Ha variant were scrapped by 1975, the Hb and Hc had followed by 1981 and the Hg and Hg2 were gone by 1993. Today, ten are still existing.