I have recently tested a motor ( step voltage insulation test) using Baker AWA IV without influence of rotor and observed its winding insulation resitsance in megohms is fine.
however the same motor after rotor and complete assembly installation when tested gives high leakge current and low megohms at high voltage .
please can I please know from the experts the possible causes for failure ?
Motor bearings were found damged and its particles were stuck in the stator winding due to which winding cleaning was done from workshop.
subsequently it was tested and found to be ok. after being in operation for two days pump went into fault.