Water rheostat for shipyard use

The liquid (or water) rheostat has been widely used for many years as a secondary or rotor resistance for speed control of large wound rotor induction motors, as a test load of approximately unity power factor for small and medium-sized generating plants up to about 10000 kW, and as an accelerating rheostat for large DC motors. The principle of operation, the various types and configurations, and the most prevalent problems relating to this equipment is reviewed. It then describes the evolution of a particular type of liquid rheostat designed primarily for use as a test load in shipyards.