Method and apparatus for inspecting laminated iron core stacks for interlamination shorts
First Claim
1. A method of inspecting a laminated core stack of an electric machine for interlamination shorts, in which method the core stack is magnetized by means of an auxiliary winding and the laminated surface is scanned by means of a measuring coil arrangement with a downstream measuring instrument, which method comprises determining, by means of at least two electrically separated, radially spaced, but mechanically interlinked measuring coils of said measuring coil arrangement, the radial distribution of the magnetic field of the current (IF) due to the interlamination short from at least on of the phase difference and the change in amplitude of the voltages (UM1, UM2) induced in the at least two measuring coils.
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Accused Products
Abstract
In order to detect interlamination shorts (8 ) in the case of laminated core stacks, the core stack (1) is magnetized with an auxiliary winding. The iron surface (15) is scanned with a measuring coil arrangement (5) comprising two electrically separated, mechanically interlinked coils (6, 7). The output signals from the coils are compared with each other in a downstream measuring instrument (9); in the case of an interlamination short, the fault current through the short-circuited laminations will induce in the coils different, phase-shifted voltages which make it possible to infer the position and size of the interlamination shorts.
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Citations
7 Claims
- 1. A method of inspecting a laminated core stack of an electric machine for interlamination shorts, in which method the core stack is magnetized by means of an auxiliary winding and the laminated surface is scanned by means of a measuring coil arrangement with a downstream measuring instrument, which method comprises determining, by means of at least two electrically separated, radially spaced, but mechanically interlinked measuring coils of said measuring coil arrangement, the radial distribution of the magnetic field of the current (IF) due to the interlamination short from at least on of the phase difference and the change in amplitude of the voltages (UM1, UM2) induced in the at least two measuring coils.
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7. An apparatus for carrying out the method of inspecting a laminated core stack of an electric machine for interlamination shorts, wherein the core stack is magnetized by means of an auxiliary winding and the laminated surface is scanned by means of a measuring coil arrangement with a downstream measuring instrument, said apparatus comprising an auxiliary coil for magnetizing the core stack, said measuring coil apparatus comprising, at least two electrically separated, radially spaced, but mechanically interlinked measuring coils, which are used to determine the radial distribution of the magnetic field of the current (IF) due to the interlamination short from at least on of the phase difference and the change in amplitude of the voltage (UM1, UM2) induced in the at least two measuring coils, measuring means connected to the measuring coils for detecting at least one of the phase angle deviation and the changes in amplitude of the voltages (UM1, UM2) induced in the measuring coils, and a recording unit connected to the measuring means.
Specification