Abstract
C2H2, C2H4, and C2H6 are important oil-dissolved gases in power transformers. Detection of the composition and content of oil-dissolved gases in transformers is very significant in the diagnosis and assessment of the state of transformer operations. The commonly used oil-gas analysis methods have many disadvantages, so this paper proposes a Ni-doped carbon nanotube (Ni-CNT) gas sensor to effectively detect oil-dissolved gases in a transformer. The gas-sensing properties of the sensor to C2H2, C2H4, and C2H6 were studied using the test device. Based on the density functional theory (DFT) the adsorption behaviors of the three gases on intrinsic carbon nanotubes (CNTs) and Ni-CNTs were calculated. The adsorption energy, charge transfer, and molecular frontier orbital of the adsorption system were also analyzed. Results showed that the sensitivity of the CNT sensor to the three kinds of gases was in the following order: C2H2 > C2H4 > C2H6. Moreover, the doped Ni improved the sensor response, and the sensor response and gas concentration have a good linear relationship.
Highlights
The special structures and properties of carbon nanotubes (CNTs) have attracted a great deal of attention of researchers at home and abroad since Iijima [1] introduced CNTs in 1991
The results indicate that the Ni-doped carbon nanotube (Ni-CNT) sensor is most sensitive to C2H2 under the same concentration conditions compared with the other two kinds of gases
In the CNT system: The values of the energy released in adsorptions are as follows: C2H2 > C2H4 > C2H6, all of them are small (
Summary
The special structures and properties of carbon nanotubes (CNTs) have attracted a great deal of attention of researchers at home and abroad since Iijima [1] introduced CNTs in 1991. CNT gas sensors exhibit a fast response, high sensitivity, small size, and low working temperature [11,12].Transformers are expensive and significant electric components in power transmission and distribution systems. Their safety and stable operation is critical to the whole power system. Gas sensing detection technology is the core of an online monitoring device, which directly affects the accuracy and stability of on-line monitoring systems together with its service life. Metal oxide sensors have high working temperatures, long response times and poor selectivity which make them unsuitable for detecting oil dissolved gases [17,18]. The Ni-doped CNTs (Ni-CNTs) sensors strengthen the adsorptions, and show improved sensor responses to C2H2, C2H4, and C2H6
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