15 kV AC railway electrification

But even at 3 kV, the current needed to power a heavy train (particularly in rural and mountainous areas) can be excessive.

High inductive reactance of the motor windings caused commutator flashover problems and the non-laminated magnetic pole-pieces originally designed for DC exhibited excessive eddy current losses.

In the German-speaking countries, high-voltage electrification began at 16+2⁄3 hertz, exactly one third of the national power grid frequency of 50 Hz.

Austria, Switzerland and Southern Germany switched their power plants to 16.7 Hz on 16 October 1995 at 12:00 CET.

Low frequency transformers need to have heavier magnetic cores and larger windings for the same level of power conversion.

Simple European unification with an alignment of voltage/frequency across Europe is not necessarily cost-effective since trans-border traction is more limited by the differing national standards in other areas.

To equip an electric locomotive with a transformer for two or more input voltages is cheap compared to the cost of installing multiple train protection systems[citation needed] and to run them through the approval procedure to get access to the railway network in other countries.

Although newer locomotives are always built with asynchronous motor control systems that have no problem with a range of input frequencies including DC, the required additional pantographs and wiring are not universally installed in order to offer cost-reduced models like the Siemens Smartron.

Likewise, newer regional passenger trainsets such as the Bombardier Talent 2 series are not certified for additional electrification systems.

Despite the Deutsche Bahn train operator does not use any models from the standard electric locomotive series anymore, many smaller private rail companies do, though some are now as much as 60 years old.

Meanwhile, DB Schenker tends to order freight locomotives that are capable of running multiple electrification systems as these operate across Europe.

In Sweden, Norway, Mecklenburg-Western Pomerania and Saxony-Anhalt, the power is taken directly from the three-phase grid (110 kV at 50 Hz), converted to low frequency single phase and fed into the overhead line.

The frequency of 16.7 Hz is determined based on the need to prevent synchronism issues in components of the rotary machine.

Therefore, the centralized system's frequency was set at 16.7 Hz to ensure that synchronism is avoided and the machinery operates correctly.