When electricity leaves the power station, it has a frequency of 50 hertz (Hz). This means that the current changes direction 50 times per second between positive and negative. At the start of railway electrification, there were no train motors capable of running on 50 hertz frequency. Therefore, converter substations were needed to convert the current to a lower frequency, 16 2/3 hertz.

Even though modern motors could use the 50 hertz frequency, it is too significant of a project to change the standard from 16 2/3 hertz. The same standard exists today in Norway, Germany, Austria, and Switzerland. Trains traveling between countries with different standards, such as on the Öresund Bridge, must be able to handle both systems.

The model depicts a rotating converter. To convert the incoming current frequency of 50 hertz to the railway's 16 2/3 hertz, the incoming power grid drives a 6000-volt synchronous motor with twelve poles. The motor rotates an axis and drives a generator with four poles. Since the number of poles is twelve versus four, the frequency decreases to one-third. The model shows a relatively small converter, but larger ones with up to three times the power exist.

Rotating converters on wagons are still in operation today at many converter substations. At modern converter substations, the frequency is converted by stationary static converters, where the frequency is changed without movement.

The converter wagon represented by the model was manufactured by ASEA in 1934.