Abstract: A rheostat of the kind that comprises a tank containing electrolyte and at least two electrodes, one electrode being connectable to an electric power supply and the other electrode being connectable to apparatus to be fed by the power supply. The electrodes define therebetween an electrolyte flow path and there is associated with the electrolyte flow path operational pumping apparatus providing for a controlled effective circulation of the electrolyte between the electrodes. The rheostat is particularly usable in conjunction with the starting of squirrel-cage motors.

Abstract: A variable level liquid rheostat having a tubular overflow member between a starting chamber and a tank for controlling the level of electrolyte in the starting chamber. The overflow member has a closed upper end inside the starting chamber and lateral discharge orifices and communicates with the electrolyte in the tank. The overflow member produces a siphoning effect when the electrolyte level in the starting chamber is substantially above the discharge orifices for causing a sudden drop of the level in the starting chamber until the electrolyte level in the starting chamber again reaches the discharge.

Abstract: An electrode for a liquid rheostat comprises a plurality of globally annular elements arranged successively and electrically connected together two at a time. The annular elements progressively decrease in size. The electrode can be formed from a continuous metal strand wound in a spiral, the turns of the strand forming the annular elements. A liquid rheostat including such electrodes is particularly suitable for starting an electric motor as it produces a gradual start up characteristic.