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Method for detection of interlaminar sheet short circuits in the stator sheet core of electromachines

A technology for stator laminations and gaps, which is applied in the field of detection of motors and interlayer short circuits, and can solve problems such as additional costs

Active Publication Date: 2014-07-30
GENERAL ELECTRIC TECH GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The disadvantage of this measuring method is that additional expenditure is required for the high-frequency generator for the excitation current
Furthermore, it is disadvantageous that it is necessary to work with precisely set and known or measured values ​​of the stator inductions, since the measured results are compared with absolute limit values ​​and then evaluated

Method used

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  • Method for detection of interlaminar sheet short circuits in the stator sheet core of electromachines
  • Method for detection of interlaminar sheet short circuits in the stator sheet core of electromachines
  • Method for detection of interlaminar sheet short circuits in the stator sheet core of electromachines

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Embodiment Construction

[0039] As already explained at the outset, and like the conventional ELCID method, the novel method operates with a low inductive excitation and a measuring coil for measuring the leakage magnetic field. However, it is particularly distinguished in that the stator is magnetized with a non-sinusoidal (or phase-shifted cosine-shaped) excitation voltage signal curve.

[0040] Typically, especially according to the invention, for example rectangular, trapezoidal, sawtooth-shaped or generally pulse-shaped excitation voltages are used. The period P of the excitation voltage can correspond to the period of the mains voltage, or can also be different therefrom, for example smaller. It is also possible to use aperiodic voltage forms, such as monopulses, for excitation.

[0041] Here generally the rectangular excitation voltage V (see also Figure 5 a) understood as a change curve, for the change curve:

[0042] V(t)=+x, 0≤t

[0043] V(t)=-x, p / 2≤t

[0044] Apply a trapezoi...

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Abstract

A method and an apparatus are described for detection of interlaminar laminate shorts in the laminated stator core of electrical machines, in which the laminated stator core (4) is subjected to an externally applied field current (2) or field voltage (V), and the short-circuit magnetic field (Bshort) induced by short-circuit currents (5) is measured with the assistance of a sensor coil (S1) which is arranged in the gap in the machine and probes this gap. Improved identification of laminate shorts, in particular even of small laminate shorts with small short-circuit currents, is possible in that a field current (2) and a field voltage (V) are applied which have a waveform which differs significantly from a sinusoidal shape, in particular with a periodic character, and have significant harmonic components in the high frequency range. By way of example, a waveform in the form of a square-wave curve is proposed.

Description

technical field [0001] The invention relates to a method for detecting laminar short circuits in a stator lamination stack of an electric machine, in particular a large generator. It relates in particular to the development of devices and methods in which the stator lamination stack is subjected to an excitation current or an excitation voltage applied from the outside and the induced short-circuit current is detected by means of a sensor coil which is arranged in the machine gap and detects this gap. short-circuit magnetic field. Background technique [0002] Large generators and electric motors are usually checked for short circuits at rest. There are different methods available for this. [0003] One of these methods consists in magnetizing the entire lamination at grid frequency by means of an auxiliary coil and measuring the leakage magnetic field on the inner surface of the stator bore. This magnetization occurs at a relatively low magnetic induction value, typicall...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/34
CPCG01R31/34
Inventor M·霍贝尔斯贝格尔
Owner GENERAL ELECTRIC TECH GMBH