This paper puts forward a kind of gearbox fault diagnosis methods which based on empirical mode decomposition (EMD), Hilbert transform, Fast Fourier Transform (FFT) and spectrum refined techniques. This method is applicable to the analysis of the nonlinear unsteady signal. First of all used wavelet denoising to the acquisition of gearbox vibrate signal, again carries on the empirical mode decomposition (EMD), than get a certain number of intrinsic mode function (imf); Choose the specific imf, based on kurtosis value, after the Hilbert transform and Fast Fourier Transform is done, the corresponding power spectrum can be obtained; To refine the power spectrum and extract the gearbox fault characteristic frequency; Then in pattern recognition and diagnosis of the gearbox fault, and compared with the normal signal characteristics. The analysis results show that the proposed method can effectively detect the gearbox fault characteristics.
Because some composite insulators run certain number of years and tends to exist insulation breakdown performance degradation issues, and some even mass incidents have occurred, affecting the normal operation of the grid. First introduced X-ray inspection systems, then introduction common failure and the reason of composite insulators. And through the artificial gap between the mandrel and the jacket seams, V-shaped mandrel and an artificial scratches and other defects between the insulator strings, concluded the feasibility of X-ray diagnosis of common faults of composite insulators.
Through the visual inspection, the appearance of size measurement, crimping size measurement, the steel core crimping length measurement and steel core tensile strength test of tension crimp barrel on 220kV transmission line. Made a detail analysis on test results combined with wire crimping theory. Pointed out the wire crimping defects caused by crimping irregularities. Analyzed the main causes of rupture accident, and made recommendations for improvement. Provides a reference to wire crimp and wire accident analysis.
For gearbox common type of fault, leads to common methods gear fault diagnosis, according to the various parameters of the gearbox, to give a gearbox fault frequencies. Using mat lab signal analysis, by the time domain analysis, frequency domain analysis, cestrum analysis, signal processing methods envelope spectrum consolidated results there is a fault in the gearbox countershaft. This papers they have certain significance to gear fault diagnosis.
Turbine blades crack problem is widespread. Combined with the characteristics of hydropower, analyzes the causes of cracks in the turbine, materials, design and manufacturing, operation and so on. Plant No. 6 in Little Bay machine as an example, were detected by macroscopic, chemical composition analysis, crack cross-section analysis, microstructure examination, crack source electron microscopy and spectroscopy to analyze the crack, the final cause of the crack is leaves the local area resonance, the resonance of the blade in the crater formed at the source of fatigue and fatigue development along at the source, the formation of fatigue cracks.
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