Analysis of SF6 decomposed products by fibre-enhanced Raman spectroscopy for gas-insulated switchgear diagnosis

Sulphur hexafluoride(SF6)decomposed products analysis is highly critical in the earlystage fault diagnosis of gas-insulated switchgear(GIS).Spectrum technology outperforms traditional methods on non-invasiveness,no sample preparation,and no consumption.Here,the authors present an improved fibre-enhanced Raman spectroscopy(FERS)as a comprehensive analytical tool to detect a suite of SF_(6)decomposed products(SO_(2)F_(2),SOF_(2),SO_(2),H_(2)S,CF_(4),OCS,CO_(2),and CO).The FERS approach is combined with two iris diaphragms for spatial filtering and a rear-end reflector for additional Raman signal enhancement.Limits of detection down to 1×10^(−6)–8×10^(−6)are achieved for different SF6 decompositions,and quantification of an undefined multigas,sampled from an 800 kV GIS in service,is realised utilising SF6 as the internal standard gas and with a maximum error of 5.5%.The GIS is diagnosed according to the results and confirmed by an on-site check.The authors foresee that this technique will provide a route for trace gas analysis in the power industry.

Functionalised B-Cu@F-Ag@Au trimetallic nanomaterials with long term stability for rapid and highly sensitive in situ SERS detection of furfural in transformer oil

The surface-enhanced Raman scattering(SERS)substrates enable a highly sensitive detection of furfural in the transformer oil.However,detection substrates with long-term stability are still extremely challenging.In this work,we anchored the thiol-containing coupling agents 2,5-dimercapto-1,3,4-thiadiazole(DMTD)and 1,4-benzenedithiol(BDT)on the surface of bubble copper(B-Cu)and flower-like silver nanoparticles(FAg),respectively.The three-dimensional SERS detection substrates with long-term stability by using a combination of chemical reduction and self-assembly methods were constructed.The substrate has a minimum detection limit of 10^(−9) M for rhodamine B in oil with an enhancement factor of up to 2.23×10^(7).Importantly,the three-crystal BCu@F-Ag_(1)@Au_(5) substrate was used for the detection of furfural in the transformer oil with a detection limit of 2 mg/L and a relative standard deviation value of 2.46%.After 60 days of a simulated operation,the detection signal of furfural in the transformer oil samples at 75℃ and still reached the initial value of 77.53%,indicating that the substrate has a good long-term stability.This triple frame structured SERS detection platform shows great potential in tracking furfural in the aging transformer oil mixing systems.

Review of optical fibre sensors for electrical equipment characteristic state parameters detection

Optical fibre sensing technology is a powerful method for long-term reliable sensing in harsh environments,which means it is particularly suitable for the detection of electrical equipment characteristic state parameters,including characteristic gases,abnormal vibration,ultrasonic produced by partial discharge,and abnormal temperature rise.This paper reviews several individual optical fibre sensors for different state parameters detection,discusses the advantages,limitations and possible improvement methods,and finally presents the most promising optical fibre sensor for each state parameter.

Oil‐paper insulation partial discharge ultrasonic multifrequency sensing array based on fibre‐optic Fabry-Perot sensor

In order to improve the sensitivity and accuracy of oil‐paper insulation partial discharge detection by the fibre‐optic Fabry-Perot(FP)ultrasonic sensor,this work studied the ultrasonic signal’s frequency characteristics of typical oil‐paper insulation partial dis-charges and the vibration characteristics of the FP sensor’s diaphragm in the liquid environment.Based on the works above,a multifrequency FP sensor array is proposed,consisting of several FP sensors with different resonant frequencies to detect partial discharges.The experimental results show that the liquid environment has a significant effect on the vibration characteristics of the FP sensor’s diaphragm,and the sensitivity and accuracy of partial discharge detection can be improved based on the multifrequency FP sensing array,which can also be applied in the pattern recognition and localisation of partial discharges.

Raman spectroscopy based detection of corrosive sulfur in transformer oil:Method and application

In order to overcome the shortcomings of traditional methods for corrosive sulfur detection in transformer oil,Raman spectroscopy based detection is proposed in this paper.The widely concerned corrosive sulfur,Dibenzyl Disulfide(DBDS),was chosen as the characteristic molecule to be detected.A series of oil samples with different DBDS concentrations was prepared.And these samples were extracted by 1-methyl-2-pyrrolidinone for DBDS enrichment to improve the sensitivity of detection.Then Raman spectra of samples were obtained,and a linear model was established by analysing the relationship between the characteristic peak and the DBDS concentration.The limit of detection reached 7.98 mg/kg.For determining the DBDS concentrations causing sulfur corrosion,the sulfur weight content on the copper conductor surface was measured by Scanning Electron Microscope-Energy Dispersive Spectrometer after a corrosion test.The results show that the corrosion limitation highly depends on the type of transformer oil,and the Raman spectroscopy detection can meet the limit of detection requirement in practical condition.Finally,an on-site oil sample and five Lab-made samples were detected via our new method and the current Gas Chromatography-Mass Spectrometry based method.It is found that there is no significant divergence between the measurement results.And good applicability was also demonstrated in onsite sample test.