Optical technology for detecting the decomposition products of SF6: a review

Abstract

Studies have demonstrated that partial discharge in SF 6-insulated electrical equipment can cause SF 6 decomposition, resulting in the generation of various products. Quantitative detection of these decomposition products can be used to evaluate the state of the equipment's insulation. The use of optical methods for detecting the products has many advantages, such as high precision, fast response, and sample reusability. Thus far, optical detection methods have been applied for detection of SF 6 decomposition products, and a few promising results have been obtained. We review the various optical technologies for detection of SF 6 decomposition products, introduce their principles and applications, and summarize some recent research progress. In addition, we propose two optical detection technologies that can be applied in this field.

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

“…where I t is the intensity of transmitted light, I 0 is the intensity of incident light, k is the molar absorption coefficient, b is the length of absorption path, c is gas concentration. Equation (2) indicates that the detection of ΔI can be used to measure the gas concentration when b is a constant. The typical structures of IAS-based fibre gas sensors [56][57][58][59][60] are shown in Fig.…”

“…The safe and reliable operation of electrical equipment is the first line of defence to avoid significant accidents in power systems. During long-term service, the operating state of electrical equipment can be reflected by various characteristic parameters, such as the electrical and thermal faults or ageing conditions can be indicated by characteristic gases [1,2], the winding deformation and core abnormality of transformers can be indicated by abnormal vibration [3][4][5], the insulation defects can be indicated by partial discharge (PD) [6][7][8][9], and the overheating faults can be indicated by abnormal temperature rise [10][11][12]. Therefore, accurately monitoring these characteristic parameters is the key to realise condition assessment and efficient maintenance of large electrical equipment, thus to ensure their safe and reliable operation.…”

Optical sensing in condition monitoring of gas insulated apparatus: a review

“…L is the path length of the beam of light through the material sample, m and α(λ) is the absorption coefficient per unit distance and per unit concentration of the gas, L/(mol•m). In order to improve the sensitivity or response time, different methods are investigated based on laser absorption, including infrared (IR) and ultraviolet (UV) spectra [17].…”

“…And almost all kinds of SF 6 decomposition products can be detected. However, if FTIR sensors want to achieve online monitoring in gas insulated apparatus, its gas cell and quantitative algorithm have to be customised [17].…”

Highly sensitive photoacoustic multicomponent gas sensor for SF6 decomposition online monitoring

“…Sulfur hexafluoride (SF 6 ) was widely chosen as the preferred dielectric gas for electrical insulation or interruption purposes in electric power systems, such as in the gas-insulated switchgear, gas-insulated circuit breaker, gas-insulated transformer, transmission line and substation, due to high dielectric strength, chemically inactive and environmentally acceptable property [1,2]. Normally, pure SF 6 is colorless, odorless, nonflammable and hard to be decomposed.…”