Laboratory experiments for the evaluation of the efficiency of induction motors operating under different electrical and mechanical faults

Abstract

The possible consequences of the presence of different faults and defects in induction motors in terms of their availability for the production process are well-known. These failures may lead to catastrophic effects, causing unexpected production downtimes and costly repairs, among many other negative effects. Nonetheless, another less perceived consequence of the existence of these failures relies on their repercussion in terms of efficiency reduction of the considered motor. It is easily understandable that the presence of different faults or defects causes a drop in the motor efficiency, but very few works have deepened in the computation of the actual efficiency decrements caused by different types of damages. In a very recent contribution, different tests were performed to calculate the efficiency reductions caused by different types of rotor damages, as well as by bearing failures, obtaining very interesting results on the impact of these failures over the motor performance. The present work is intended to deep in this area, analyzing additional mechanical and electrical faults. Different types of misalignments between motor and load, loosened bolts, cooling system problems and insulation degradation are studied, and the corresponding efficiency curves for different load levels are calculated in each case and compared with the healthy case. The results ratify the significant efficiency impact of most of these failures and emphasize the importance of a proper maintenance of the motor for enabling its optimum performance.