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The power supply of the public rail passenger transportation system is done via rectifiers supplied by the normal 50 Hz three-phase supply system. The rectifier stations are located every 500 - 2000 m near the transportation route. Here, the supply voltage of 20 - 30 kV is stepped-down and rectified to the required DCvoltage. The electricalpower supply is performed with the aid of trolley wires or with rails, in the case of trams. The current strength can reach 4 kA.Due to the low intensity trolley wire voltage the electric field strengths near the transportation route don’t exceed 50 V/m. In the interior of the trams or subways the electric field strength is almost completely shielded. However, magnetic flux densities can reach levels from 150 µT - 350 µT. Approximately 1 m away from the platform there are levels of only 50 µT - 110 µT. Typical measurement values for public rail passenger transportation systems (e.g. trams) can be found in the database of exposure sources.