At the end of the seventies, the SAR had the 50c/s Group develop the class 7E for the lines newly electrified with 25 kV alternating current. This consortium consisted of companies from Belgium, Germany, France and Switzerland and specialized in building locomotives for the modern 50 Hertz system. The 100 locomotives were built by Union Carriage & Wagon in South Africa. They became the first thyristor-controlled locomotives in South Africa and replaced the last class 25NC steam locomotives.

After 100 locomotives of the actual 7E, 50 7E1s followed, the electrical part of which was developed by Hitachi and contained solid state converters. They were built by Dorbyl in South Africa and only had one cab because they were normally only used in multiple.

From 1982 onwards, 65 7E2s were built, most of which again corresponded to the 7E. The 85 7E3, which were built from 1983, again came from Hitachi and Dorbyl. In contrast to the 7E1, they again had two cabs. Some of these were significantly modernized from 2001 onwards in the area of electrics and electronics, resulting in the different classes 7E4, 7E5 and 7E6. These were later brought up to the same standard and renamed 7E3 again.