France: BB 10001

In 1948, as part of the electrification of the Savoy railway lines using 20 kV / 50 Hz single-phase alternating current, the French National Railway Company - SNCF orders three prototypes for six-axles dual-system (alternating current and direct current) electric locomotives which will be delivered as follows:
- unit CC 6051 is delivered in 1950 by Oerlikon Machine Factory - MFO and Swiss Locomotive and Machine Works - SLM;
- unit CC 6052 is delivered in 1951 by Alstom;
- unit BBB 6053 is delivered in 1955 by Electric Traction Equipment Company - MTE and Ironworks Company and Creusot Workshops- SFAC.

In addition to this official order, Alstom also develops a locomotive solely for the 20 kV / 50 Hz single-phase alternating current system, which the firm is building at its own expense.

Sources: https://fr.wikipedia.org/wiki/BB_10001

Although it does not correspond to the initial specifications, the first tests are promising and the French National Railway Company - SNCF agrees to acquire the locomotive.

It is delivered to Chambéry depot on June 28th, 1951, and it is registered as BB 8051.

Sources: https://fr.wikipedia.org/wiki/BB_10001

This unit is renumbered BB 10001 and at the same time undergoes slight modifications because the line voltage goes from 20 kV to 25 kV.