A New Method for Stator Core Repair Reduces Core Losses and Repair Time

The steel laminations used in the stator core of electric motors and generators are electrically insulated from one another to reduce eddy-current losses. When a bearing failure results in friction between the rotor and stator, or a ground fault occurs, laminations are often fused together. Since traditional methods of core repair are labor-intensive, even moderate core damage may preclude economical repair in the few percent of motor failures with significant core damage. There is a new process that can restore the coreplate without dismantling the core, saving labor and eliminating the chance of unsatisfactory restack results. This chemical conversion process simultaneously etches interlaminar shorts and forms a durable coreplate with excellent electrical insulation. The potential benefits to industry, in terms of labor saved and reduced mean time to repair, are substantial. The cost to restack the stator core of a 5,000 kW machine can exceed $30,000 US, and require two weeks time. This new process can restore the core in less than one day