Patent ID: 6791351
Filing Date: 2004-09-14
Classification: G01R

Abstract:
An electrical generator inspection system for detecting insulation breakdown axially between two or mare adjacent laminates of a generator stator core comprising:an electromagnetic detector having an excitation coil for carrying an alternating current and inducing eddy currents in the laminates, said electromagnetic detector providing output signals representative of fault currents detected due to defects in the insulation between laminates axially along the stator core, said output signals providing information on the axial location along the stator core at which the fault currents are detected; and means for varying a frequency of the alternating current so that said output signals also provide information on a depth, radially, of the fault currents within the laminations, wherein the frequency of the alternating current is varied within a frequency range of approximately the frequency of a local electrical grid network and two kilohertz.