TEMPERATURE-RISE OF ROTATING ELECTRICAL MACHINES AS AFFECTED BY COLD TEMPERATURE MEASUREMENT

ABSTRACT

Determination of temperature-rise, of rotating electrical machines by resistance measurement, has become a problem of practical interest to all electrical manufactures. This paper describes the governing features of such measurements and thereby projecting certain recommendations. Major deductions are solely derived on experimental basis which prove to be a valuable tool to practising engineers in the heat-transfer area. Major emphasis is laid not only on the basis of accurate assessment of winding resistance, but also on the cold temperature of the winding. A clear distinction is brought out between ambient temperature and cold temperature of the winding. Paraphrasing the intutive question that is well answered here is “How one is able to determine the temperature rise of the machine accurately” and hence to appreciate the efficacy of optimization of design. The results of temperature variation on randomly chosen two days in winter and a day in summer are presented. The recommendations made here are applicable to tropical countries where there is a large difference in day and night temperature. The physical cause for this difference is also described.