Detection of broken rotor bar in squirrel-cage induction machines using stator zero-components

In this paper a method for the broken rotor bar fault detection of induction squirrel cage machines is presented. This method is based on measurements and frequency analysis of the sum of the stator phase currents (the stator circular current) for delta connected windings. For the case of the star connected windings the stator neutral point voltage is measured and analyzed. A model of squirrel cage induction machine, which takes into account the stator windings and rotor cage layout, is used for theoretical investigations of the proposed method. Based on the theoretical investigations it has been found out that the spectrum of the stator circular current, and also the neutral point voltage, contains the rotor fault-related interharmonics. At the same time, these interharmonics are the largest components in the frequency spectrum. The proposed method has been experimentally verified and compared with the procedure based on the frequency analysis of the line current.