The cadet continues:
"When France's S.N.C.F adopted 25kV A.C between Aix-les-Bains and La Roche-sur-Foron in southern France in 1953, they were in the same position as we would be adopting 30kV D.C. They were using a standard that no one else had at that time. The standard for new electrification projects has changed over time. If the advent of rectifiers on board trains made standard frequency A.C feasible, where previously either D.C with D.C motors or low frequency A.C with universal motors would have been used, then high voltage inverters on board trains should make way for D.C electrification. Only D.C electrification loads phases evenly, and D.C is the only way to deliver constant power with single wire overhead. And we need DC-DC converters to make it work at higher voltages than 3kV, we didn't back then, now we do."
The line opened from Aix-les Bains to Annecy in October 1950 and was extended to La Roche-sur-Foron in May 1951.
There were three locomotives on the line:
CC6051 from Oerlikon, which was basically a Swiss Federal Ae6/6 fitted with motors suitable for 50Hz current.
CC 6052 from Alsthom, which was basically an SNCF CC7101 fitted with a transformer and motors suitable for 50Hz current.
BB8051 from Alsthom which was a BB8100 fitted with transformer and an air cooled rectifier with DC motors.
There was also an electric multiple unit car for passenger service.
The first main line ran between Thionville near Metz to Valciennes south east of Lille.
It hadn't opened at the date of my reference, "Chemins de Fer" of March /April 1953.
Four types of locomotives were puchased:
CC14000 Co Co freight, with three phase motors and a rotary converter from single phase to three phase (20 units)
CC14100 Co Co freight, with DC motors and a rotary converter from single phase to DC (102 units)
BB12000 Bo Bo mixed traffic with transformer and rectifiers (ignitrons) and DC motors (148 units)
BB13000 Bo Bo mixed traffic with transformer and 50Hz motors (53 units)
The prices for these each at the time were:
BB 12000 96 million FF
BB 13000 98 million FF
CC 14100 121 million FF
CC 14000 136 million FF
It is clear why the rectifier locomotives won the day in 1953.
Now with solid state converters, single phase AC converted to three phase AC for the motors is almost universal.
So if Myrtone's statement is true, we might expect some years of testing different technologies and following up blind alleys before 30kV Dc electrification could be made to work...
It might also be borne in mind that the Germans tested 20kV 50Hz on the Hollentalbahn in the Black Forest area in 1936 (so fifteen years before the French)
They had four locomotives:
E244 01 with a Mercury Arc rectifier and DC motors.
E244 11 with a Mercury Arc rectifier and DC motors.
E244 21 with 50Hz AC commutator motors
E244 31 with 50Hz AC aysnchronous single phase motors
A fifth locomotive E244 22 was rebuilt from a dameaged E44 after WWII
The line was converted to standard 15kV 16.66 Hz in 1960.
None of this suggests to me that the adoption of a new system of electrification would be simple or rapid.
The German case suggests that the advantages of the higher frequency were not great enough to justify a change.