Method and device for inspecting laminated iron cores of electrical machines for interlamination shorts

• US 20030057961A1
• Filed: 05/17/2002
• Published: 03/27/2003
• Est. Priority Date: 09/24/2001
• Status: Active Grant

• Current Assignee: General Electric Technology GmbH (GE Aerospace)
• Original Assignee: Alstom Technology Ltd. (Alstom SA)
• Inventors: Kirchhoff, Ingo, Hobelsberger, Max, Posedel, Zlatimir, Nodwell, Eric
• Granted Patent: US 6,815,957 B2
• Time in Patent Office: Days
• US Class Current: 324/545
• CPC Class Codes: G01N 27/9046 by analysing electrical signals
• CPC Class Codes: G01R 31/34 Testing dynamo-electric machines

Abstract

The present invention relates to a method, an apparatus and a computer program for inspecting laminated iron cores (1) of electrical machines for interlamination shorts, in which the laminated iron core (1) is magnetized by means of an auxiliary winding, and the iron surface is scanned by means of at least one measurement coil arrangement (2) with a downstream measurement device. In this case, unique and quantifiable localization of interlamination shorts is achieved by using both the phase (8) and the amplitude (7) of the electrical signal which is induced in the at least one measurement coil arrangement (2), in combined form.

Claims

1. A method for inspecting laminated iron cores (1) of electrical machines for interlamination shorts, in which the laminated iron core (1) is magnetized by means of an auxiliary winding, and the iron surface is scanned by means of at least one measurement coil arrangement (2) with a downstream measurement device, characterized in that both the phase (8) and the amplitude (7) of the electrical signal which is induced in the at least one measurement coil arrangement (2) are used in combined form to localize interlamination shorts.

2. The method as claimed in claim 1, characterized in that interlamination shorts are localized by means of a real part (10) of the induced electrical signal, which is high in comparison to the intact regions.

3. The method as claimed in claim 2, characterized in that the high real part is determined by means of a polar representation, with the real part (10) defining the vector direction and being determined by the calibration measurement.

4. The method as claimed in one of the preceding claims, characterized in that at least one further measurement coil arrangement, which is electrically isolated from a first measurement coil arrangement (2) is used, and is radially at a distance but is mechanically connected to the first measurement coil arrangement, and both the phase (8) and the amplitude (7) of the at least two electrical signals, which are induced in the at least two measurement coil arrangements (2), are used to localize interlamination shorts, in particular to localize them in the radial direction.

5. The method as claimed in one of the preceding claims, characterized in that the induced electrical signals are compared with signals which correspond to the interlamination short currents, with a calibration current coil (9) with an appropriate width being mounted on the surface of the laminated iron core (1) as a reference for this purpose, and being fed with an appropriate interlamination short current.

6. The method as claimed in claim 5, characterized in that the volt-amperes in an interlamination short are determined quantitatively by comparison with the reference.

7. The method as claimed in one of the preceding claims, characterized in that the laminated iron core (1) is magnetized in particular via the rotor shaft from a high-power supply source which is connected between the two machine sides, in particular on the insulated shaft, in particular with the laminated iron core (1) being magnetized in the range from 0.03 to 0.7 Tesla, in particular approximately 0.1 Tesla, with a voltage of 220/110 volts at 50/60 Hz.

8. The method as claimed in one of the preceding claims, characterized in that the at least one measurement coil arrangement (2) is shifted on the laminated iron core (1) in the axial direction, and, in the process, the induced signals are determined, in particular in the form of a fingerprint, as a function of the position of the measurement coil arrangement (2), with regions with critical interlamination shorts being determined, in particular, via the real part (10) and being distinguished from regions with noncritical interlamination shorts, and with the critical regions being marked for immediate rectification, and the regions which are still noncritical at that time being documented for later analysis.

9. An apparatus for carrying out a method as claimed in one of claims 1 to 8, comprising first means for determining the position of the measurement coil arrangement (2) on the laminated iron core (1), and comprising second means for detecting the amplitude (7) and the phase (8), in particular by means of a phase detector, of the electrical voltage which is induced in the measurement coil arrangement (2), and also comprising a data processing unit, which analyzes the measured data and, in particular, is able to localize critical interlamination shorts and to determine the volt-amperes flowing in them, by comparison with a reference.

10. A computer program for carrying out the analysis in a data processing unit as claimed in claim 9, characterized in that the data, that is to say the phase (8) and amplitude (7) of the electrical current which is induced in the measurement coil arrangement (2), is changed to a vector representation in the form of a polar diagram, preferably after having been adjusted using a reference, and fault points (a) are identified automatically.

11. The computer program as claimed in claim 10, characterized in that fault points (a) are determined by the real part (10) of the signal exceeding a predetermined limit value.