Thermal classification of wire wound low voltage machines

Current activity in the field of international standardisation of procedures for thermal classification of insulation systems for machines is progressing steadily. In the low voltage wire wound field it is suggested that more attention should be paid to simplification and cost reduction. To this end it is suggested that a simple wrapped tube test procedure which is described can offer cost savings while increasing the amount of data produced. It is further proposed that there us scope for single temperature testing when this is of a confirmatory nature. It is concluded that the wrapped tube test procedure should be internationally recognised and that rules for single temperature testing be defined.