Electrical monitoring of mechanical defects in induction motor driven V-belt-pulley speed reduction couplings

V-belt-pulley couplings are commonly used for speed reduction in induction motor driven industrial applications since they provide flexible transmission of power at low cost. However, they are susceptible to mechanical defects such as belt wear or crack that can cause slippage or damage of the belt and lead to decrease in efficiency and lifetime of the system. There are many limitations to applying existing tests such as visual inspection, thermal or mechanical monitoring as they require visual or physical access to the system and/or costly sensors. Considering the large quantity of belt-pulley systems employed in industry, the impact of the economic loss incurred by low-efficiency operation and unplanned process outages is significant. In this paper, electrical monitoring of belt-pulley coupling defects based on the analysis and trending of the stator current frequency spectrum under steady-state and starting conditions is presented. The proposed method is verified on 1) 6.6 kV motor driven pulpers, and on a 2) custom-built motor driven air compressor with speed reduction belt-pulleys under controlled fault conditions. It is shown that the proposed method can provide automated, remote, and safe detection of belt-pulley defects based on existing current measurements for improving system reliability and efficiency.