On March 15, 1979, a 1920 MW thyristor based direct current connection between Cabora Bassa and Johannesburg (1,410 km) was energized. The conversion equipment was built in 1974 by Allgemeine Elektricitäts-Gesellschaft AG (AEG), and Brown, Boveri &amp; Cie (BBC) and Siemens were partners in the project. Service interruptions of several years were a result of a civil war in Mozambique. The transmission voltage of ±533 kV was the highest in the world at the time.