Insulator Detection Method Based On Laser Induced Breakdown Spectroscopy

As an important supporting equipment of transmission lines,composite insulators will inevitably decline after long-term operation due to pollution erosion,ultraviolet radiation,electric field and other environmental factors.The state assessment of composite insulators is mainly to judge the aging and contamination degree.The existing detection methods can not achieve quantitative analysis of aging and contamination degree,or exist.The testing methods are complicated,the sample requirements are strict,and the non-destructive testing is not possible.Therefore,it is very important to find a quantitative and rapid detection technology for aging and contamination of composite insulators.Laser-induced breakdown spectroscopy(LIBS)is a new technology of atomic emission spectrometry.It can be applied to the qualitative and quantitative detection of substance elements in various states(solid,liquid and gaseous),without sample treatment,multi-element synchronous analysis,high sensitivity and field detection in harsh and complex environment.Based on these advantages,it has been widely used in many fields such as industrial production.In this paper,laser-induced breakdown spectroscopy(LIBS)technology is introduced into the field of composite insulator condition detection.Aging and contamination samples of composite insulators are detected respectively.Qualitative and quantitative analysis of component elements of the sample is realized,and characteristic parameters which can characterize the aging and fouling degree of composite insulators are proposed based on the LIBS emission spectroscopy.For aging degree detection,firstly,LIBS test is carried out for composite insulators of different ages.Based on EDS energy spectrum analysis results,qualitative analysis is carried out for the constituent elements of aging samples.Local plasma thermal equilibrium is determined by calculating plasma temperature and electron density.Then,surface matrix elements,impurities and contamination of samples with different operating years are determined.At last,the principal component analysis model is established based on the change rule of impulse bombardment,which can classify and identify the service life and aging degree of composite insulators.For the detection of contamination degree,firstly,LIBS tests were carried out on artificial and natural contaminated samples respectively.Then,qualitative analysis of elements in artificial and natural contamination was realized based on LIBS emission spectra.Finally,the contamination degree of artificial and natural contaminated samples was characterized based on the spectral intensity of elements in LIBS emission spectra.It was found that the salinity and grey density of artificial contamination can be characterized by the characteristic spectral line strength of Na and Al elements respectively,while the natural contaminated samples can not be directly characterized by the spectral line strength of characteristic elements due to matrix effect and other factors.The influence of matrix effect can be effectively eliminated by the relative strength of the contaminated elements(the ratio of the spectral strength of the contaminated elements to that of the matrix element Si)in the naturally contaminated samples to characterize the contamination degree of the naturally contaminated samples.The above research results provide a theoretical basis and practical basis for the application of laser induced breakdown spectroscopy technology in the aging and contamination detection of composite insulators.