Abstract: A rotating electric machine comprising a stator 1 and a rotor 5 which is adapted to be rotated about an axis and which is disposed opposite said stator 1. Normally, the magnetic field of the rotor is excited by a direct current which is supplied via sliding contacts. In order to avoid wear of the sliding contacts, the invention employs the measure that the exciting current for the magnetic field of the rotor is supplied via a second stator 13 and a second rotor 9 by means of induction.

Abstract: An electrolytic water sterilization system comprises a rate detecting cell, an oxidation cell and a silvering cell through which the water flows. The rate detecting cell is fitted with two electrodes and is partly filled with non-conducting particles whose density is greater than water. The upwards flow of water expands the bed of particles providing greater free area between the electrodes. The electrical resistance between the electrodes is reduced accordingly. The current to the electrodes of the oxidation cell and the silvering cell is controlled by the detected flow rate. Preferably, the rate detecting cell, the oxidation cell and the silvering cell with their corresponding electrodes are combined in one single cell.