Experimental three-phase railcar

1879 saw the demonstration of an experimental system by Werner von Siemens in Berlin, which was followed by an electric tramway at Lichterfelde, in 1881, and heavy rail applications in 1890 (the City and South London Railway) and 1895 (the Baltimore Belt Line).

To study the possibilities of AC, for the upcoming Three-phase AC railway electrification that started in mountain areas of Switzerland and Italy, in 1899 a consortium of ten of the largest and wealthiest companies in Germany joined to form the "Research Association for High-speed Electric Railways"(Studiengesellschaft für elektrische Schnellbahnen, or St.E.S.)

The St.E.S consortium, which included Siemens & Halske, the engineering company AEG, and the Deutsche Bank, was founded on 10 October 1899 and given leave to electrify a length of the Royal Prussian Military Railway between Marienfelde, near Berlin, and Zossen, a distance of 23 kilometres (14 mi).

These were built by Van der Zypen & Charlier [de], a Cologne rolling-stock manufacturer established in 1845 and consortium member, with Siemens and AEG supplying the electrical equipment.

The cars were of standard size, with a capacity for 50 passengers, mounted on two six-wheel bogies, the outer axle being motorized.

[1] The tests had shown what was possible with electric motive power, but the three-phase system was too complex, and the cost of installation too prohibitive, for general use across the rail network.