No tooling cost process for induction motors energy efficiency improvements

In this paper, the analysis of some possibilities for increasing the induction motor efficiency using production technological process modifications is reported. This approach is known as the "no tooling cost" (NTC) strategy because it does not require a complete redesign of new laminations with a consistent cost in terms of investments. The paper shows the results obtained by a full experimental approach, using "ad hoc" prototypes. The NTC design modification and the technological processes analyzed in this paper have been done on totally enclosed fan-cooled standard induction motors. Obviously, the original motors have been compared from the energetic point of view with these prototypes. The energetic performance has been measured in accordance with the IEEE Std. 112-96 Method B. In particular, the following modifications, for obtaining an increase in efficiency, have been taken into consideration: rotor with copper bar included in the slot before the aluminum die cast, increase of the core axial length, and annealing of the stator core.