Step switching

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As stage circuit is defined as the control of electric rail traction vehicles , wherein the drive motors for speed adjustment on the drive switch to be connected to an existing of a plurality of voltages.

In DC vehicles, various starting resistances are switched via the step switching, the traction motors are initially operated in series and in the higher speed steps in parallel.

In AC vehicles, the traction motors are connected to the various taps on the transformer via the tap changer . In order to avoid switching high currents at higher outputs, taps are also used on the high-voltage side of the transformer.

Due to the limited number of steps, the disadvantage is a noticeable jump in pulling force (short "jerk") when switching the steps when accelerating.