Unconventional electrical machine for circulating molten metal

The paper deals with the application of an unconventional electrical machine for circulating molten aluminium in reverberatory furnaces. Its design is based on the classical jumping-ring principle, and it incorporates some hitherto less known aspects of open magnetic circuits and of the concepts of flux spreading. Results of trials using a prototype machine are given, and the metallurgical and other benefits which accrue from its use are discussed. To maintain the electromagnetic integrity of this machine at liquid-metal temperature (> 700¿¿C), a study of its thermal behaviour is made using a mathematical model. This model is subsequently verified by experimental observations. Proposals are made for the future use of some unconventional electrical machines in an aluminium remelt plant.