Patent Document ID: 9605710
Application ID: 13582251
Patent Status: 1

Claim One:
1. A method for early detection of developing damage in a bearing of an electric motor caused by flow of a bearing current, comprising the steps of: measuring, in a test bed and before an ongoing operation of the bearing, during a measuring time longer than 1 ms, bearing currents having a duration of faster than 20 ns with a bearing current sensor or bearing voltage sensor, or both, which are is permanently installed on a motor, wherein the bearing is subjected to predefined electrical and mechanical loads, recording, in form of a first histogram, a frequency of occurrence of bearing currents across the bearing as a function of a bearing current amplitude, differentiating based on a first characteristic pattern in the first histogram between electric discharge machining (EDM) currents, circular bearing currents and rotor ground currents, measuring, during the ongoing bearing operation, at least one variable representative of a bearing current amplitude of a bearing current having a duration of faster than 20 ns with the bearing current sensor or the bearing voltage sensor, or both, evaluating, for a measuring time longer than 1 ms, at least one long-term measurement of the at least one variable with a bearing current evaluation unit, displaying results from the at least one long-term measurement in a second histogram which displays the frequency of occurrence of bearing currents as a function of the bearing current amplitude during the ongoing bearing operation in a user interface, differentiating, based on a second characteristic pattern in the second histogram between the electric discharge machining (EDM) currents, circular bearing currents and rotor ground currents, comparing the first and second characteristic patterns of the histograms with respect to the EDM currents, and detecting the developing damage based on the comparison.