KR-20260066002-A - GAS SENSOR HAVING STABILITY UNDER CONTINUOUS EXPOSURE TO ACETYLENE

Abstract

The present invention provides a gas sensor having stability against continuous exposure to acetylene, comprising: a substrate; and a heterostructure nanofiber formed by electrospinning on the substrate; wherein the nanofiber is formed by combining metal oxide semiconductors, and the content of the metal oxide semiconductor is controlled to form a heterostructure nanofiber of CuO and ZnO, and the metal oxide semiconductor is mixed in a molar ratio of CuO : ZnO = 8 : 2, and has gas selectivity for acetylene under conditions of 200°C or lower and an oxygen concentration of 2% or less, and has a gas reactivity (Rg/Ra) of 7.6 for 10 ppm acetylene gas , wherein Ra represents the sensor resistance in a stabilized state in an atmosphere with an oxygen concentration of 2% or less, and Rg represents the sensor resistance after injecting acetylene gas in the atmosphere, and has stability without drift when 5 ppm C₂H₂ is injected 10 times continuously for 10 hours.

Inventors

• 정미희
• 임대광
• 최철

Assignees

• 한국전력공사

Dates

Publication Date

20260512

Application Date

20260326

Claims (1)

1. Substrate; and A heterostructured nanofiber formed by electrospinning on the above substrate; comprising The above nanofiber is composed of metal oxide semiconductors bonded together, and is formed as a heterostructure nanofiber of CuO and ZnO by controlling the content of the metal oxide semiconductors. The above metal oxide semiconductor is mixed in a molar ratio of CuO : ZnO = 8 : 2, and It has gas selectivity for acetylene under conditions of 200℃ or lower and an oxygen concentration of 2% or less, and a gas reactivity (Rg/Ra) of 7.6 for 10 ppm acetylene gas, wherein Ra represents the sensor resistance in a stabilized state in an atmosphere with an oxygen concentration of 2% or less, and Rg represents the sensor resistance after injecting acetylene gas in the said atmosphere. Having stability without drift when 5ppm C₂H₂ is injected 10 times consecutively over 10 hours , Gas sensor with stability against continuous exposure to acetylene.

Description

Gas sensor having stability under continuous exposure to acetylene The present invention relates to a gas sensor. More specifically, it relates to a gas sensor that has stability during continuous exposure to acetylene. Transformers play an irreplaceable role in managing power transmission and voltage in today's complex power systems. Among transformers, oil-filled transformers are the most widely used in power systems, and they are widely distributed worldwide due to their cost-effectiveness and unlimited optimal voltage. Oil-filled transformers prevent accidents by using insulating oil to lower internal temperatures and insulate current. However, accidents caused by abnormal phenomena such as breakdowns, discharges, or faults can lead to catastrophic disasters resulting in power outages, and their frequency cannot be ignored. One effective method for managing and predicting such accidents is to monitor the decomposition gases of transformer oil through Dissolved Gas Analysis (DGA). When a transformer fails, heat is typically generated at a single point, causing the insulating oil to decompose. The decomposition products include hydrogen ( H₂ ), hydrocarbons ( CH₄ , C₂H₂ , C₂H₄ , C₂H₆ ), and carbon oxides (CO, CO₂ ). The types and concentrations of these gases vary depending on the type of failure and serve as key indicator gases. Among these various gases , acetylene ( C₂H₂ ) is generated by the arc at a maximum temperature of around 750°C and is the most important gas to monitor because even a few ppm (5–7 ppm) indicates the possibility of a transformer explosion. Therefore , it is of utmost importance to accurately monitor dissolved acetylene ( C₂H₂ ) at very low concentrations in all transformers. Until now , DGA of C₂H₂has primarily been performed using chemical analysis via gas chromatography (GC) due to its high sensitivity and accuracy. However, there is a problem in that dissolved gases can diffuse into the atmosphere due to the time difference between gas extraction and GC analysis, potentially leading to inaccurate results. Recently, there has been an increase in the adoption of Internet of Things (IoT) systems utilizing GC to effectively manage a large number of transformers; however, it is practically difficult to install GC on every transformer in a substation due to high purchase, installation, and operating costs, as well as the large volume of the DGA system. Therefore, there is a need to replace them with gas sensors that have a simple structure, high accuracy, and low cost. As background technology for the present invention, Korean Patent No. 10-1620585 discloses a zinc oxide-graphene hybrid-based acetylene gas sensor coated with silver nanoparticles and a method for manufacturing the same, but the manufacturing cost is high and it is not suitable for operation in the internal environment of an incoming transformer. FIG. 1 is a process flow diagram of a method for manufacturing a gas sensor according to another aspect of the present invention. FIG. 2 is a schematic diagram showing the process of manufacturing heterostructured nanofibers according to one embodiment of the present invention. Figure 3 shows the TGA analysis results according to the heat treatment process for heterostructured nanofibers according to one embodiment of the present invention. FIG. 4 shows a gas sensor according to one embodiment of the present invention placed on an expansion platform, where (a) is a front sensing portion and (b) is a rear heating portion. FIG. 5 is a photograph and an SEM photograph of a gas sensor according to one embodiment of the present invention. Figure 6 shows SEM, TEM-EDS analysis images of heterostructure nanofibers and copper oxide according to one embodiment of the present invention, XRD analysis results, Zn/Cu relative peak intensity of XPS analysis according to composition, and XPS analysis results of a sensing material containing heterostructure nanofibers. Figure 7 is a TEM image of a heterostructure nanofiber and a pure copper oxide nanofiber according to one embodiment of the present invention. Figure 8 is a STEM image of a heterostructured nanofiber according to one embodiment of the present invention. FIG. 9 shows the gas reactivity and selectivity of a gas sensor according to one embodiment of the present invention. FIG . 10 shows the real-time resistance change of a gas sensor according to one embodiment of the present invention for H₂ , CH₄ , C₂H₄ , C₂H₆ , CO , and CO₂ at different concentration ranges. FIG . 11 shows the reactivity of a gas sensor according to one embodiment of the present invention to H₂ , CH₄ , C₂H₄ , C₂H₆ , CO , and CO₂ at different concentration ranges. FIG. 12 shows the detection characteristics of a gas sensor according to Example 5 compared with other gas sensors in a gas sensor according to one embodiment of the present invention. Figure 13 shows the SEM and EDS analysis results of copper and zinc film sensors. FIG. 14 shows a sensing mechanism of