Method and device for the early detection of the development of damage in a bearing

• US 9,605,710 B2
• Filed: 03/01/2010
• Issued: 03/28/2017
• Est. Priority Date: 03/01/2010
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Hassel, Jrg, Probol, Carsten, Tischmacher, Hans
• Primary Examiner(s): Kundu, Sujoy
• Assistant Examiner(s): Dinh, Lynda
• Application Number:
  US13/582,251
• Publication Number:
  US 20130066566A1
• Time in Patent Office: 2,584 Days
• Field of Search: 702 34- 35
• US Class Current: 1/1
• CPC Class Codes: F16C 19/52 with devices affected by abnormal or undesired conditions
• CPC Class Codes: G01D 3/00 Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
• CPC Class Codes: G01D 3/08 with provision for safeguarding the apparatus, e.g. against abnormal operation, against breakdown

Abstract

A method for early detection of developing damage in a bearing caused by flow of a bearing current includes evaluating a long-term measurement of a measured variable representative of a bearing current amplitude of a bearing current during a bearing operation, representing—based on the evaluation—measurement results in form of a histogram which displays a number of bearing currents per time interval in each interval of the bearing current amplitude, and evaluating the histogram representation of the measurement results through pattern comparison. A device for carrying out the method is also disclosed.

Claims

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.

2. The method of claim 1, wherein the at least one long-term measurement is performed over a measurement time having a duration between 1 ms and one hour.

3. The method of claim 1, wherein the at least one long-term measurement is performed over a measurement time having a duration between one hour and at least one day.

4. The method of claim 1, wherein the measured variable is a variable which is characteristic of a discharge time and a discharge amplitude.

5. The method of claim 1, wherein the measured variable is a variable which is characteristic of at least one of the following features:

the bearing current amplitude or a bearing voltage or a slope of the bearing voltage or at least one indirect variable selected from an electrical and an electromagnetic field.

6. The method of claim 1, wherein the at least one long-term measurement is carried out on a test bed under load.

7. The method of claim 1, wherein the long-term measurement of the bearing is carried out in a facility.

8. The method of claim 1, wherein the histogram is graphically displayed.

9. The method of claim 1, and further comprising the step of performing a trend analysis of the second characteristic pattern.

10. The method of claim 1, and further comprising the step of measuring during ongoing bearing operation at least one additional variable selected from vibrations, temperature, terminal voltage in a motor, lubrication state, and motor current.

11. The method of claim 1, wherein the measured variables are retrieved through remote access.

12. The method of claim 1, and further enabling a user to control evaluation of the at least one long-term measurement through commands changing a measuring range, a measuring filter, a measuring frequency, evaluation parameters and width of an interval of the bearing current amplitude in the histogram.