Research on on-line DGA using FTIR [power transformer insulation testing]

Abstract

these two kinds of detectors are still in its infancy and have Abstract-Electrochemical sensors and gas chmmatography ' encountered many problems that optical detecting methods are widely used in on-line monitors for dissolved gas-in-oil of power transformers, but some fatal defects exist. In view of the many advantages of FTIR, the basics of applying it on such monitors are studied and results are prcsented. Investigation shows that ail the characteristic Deal\s needed to be analwed could avoid naturally. The most outstanding advantages of an optical detector are their non.destruct,ve and no characteristics; and with FTIR spectroscopy, it is reported'"' that the amount of all the diagnostic gases as well as water can be covered if the measurable wavenumber rcgion of the spectrometer is 720cm.'-3400cm.', and the optimum optical content except hydrogen could be measured slmultanwusly m a satisfactory precision that such B monitor'can. be consiructed using FTIR that can FTIR spectroscopy are investigated recently'"', no rePo* on Dreciselv detect all the diamostic eases excent hvdrocen and are FTIR suectra used in DGA has been made in China. " 0 . ~ ~. free of consuming gases as well as in situ calibration.Index Term-DGA, dissolved gas-in-oil, FTIR, gas cell, infrared spectra, on-line monitoring, optical length, power transformer.

A Review of Methods for Diagnosing Incipient Faults in Power Transformers using Dissolved Gas Analysis

“…Some of the methods used to analyse the composition of dissolved gases in transformer oil include spectroscopic methods like gas chromatography, Fourier Transform infra-red spectroscopy (FTIR), photoacoustic spectroscopy (PAS) and ultraviolet-visible spectroscopy (UV-Vis) [17][18]. Compact and portable chemical sensors that can detect and quantify the presence of specific gases in the insulating oil can also be used but generally have sensitivity and selectivity issues [19].…”

Laser Calorimetry Spectroscopy for ppm-level Dissolved Gas Detection and Analysis

“…The absorption spectrum of transformer oil cannot be directly obtained from any database. Several studies have been done to measure the transmission of mineral oil (transformer oil) 21 22 23 . However, different transformer oils can have different optical properties.…”

Study on Online Monitoring System of Power Transformer

“…The sensing element of optical fiber grating vibration sensor is double fiber bragg grating arranged in a fiber, they have the same center wavelength and low reflectivity, double fiber bragg grating is fixed on the base by cantilever beam. The double fiber bragg grating, the cantilever beam and the base are packaged in a high temperature resistant plastic shell, that form a low finesse optical cavity [3], it can detect mechanical vibration of power transformer's shell, internal coil's winding and the conducting wire's joint . At the time of detection, as the cantilever beam is in a wide frequency range, it can perceive the mechanical vibration of power transformer and changes the optical properties, such as the variation of the center wavelength or phase of reflected light, so that the intensity of interference light produced from low precision interferometric changes with mechanical vibration of the power transform corresponding.…”