Transformer oil-dissolved methane detection based on non-adiabatic tapered fiber using polyacrylate and cryptophane-A overlay deposition

Transformer overheating faults can lead to an increase in the transformer oil-dissolved methane content, therefore, the high-precision in-situ detection of oil-dissolved methane is significant for early-stage transformer fault diagnosis. However, traditional methods can not achieve in-situ monitoring, and there is a shortage of methane-sensitive materials. To enable high-sensitivity in-situ detection of transformer oil-dissolved methane, this paper proposed a methane sensor based on the evanescent field of the non-adiabatic tapered optical fiber (NATOF), utilizing the specific adsorption of cryptophane-A to methane. A NATOF with a waist diameter of 8.17 mu m and length of 8 mm was fabricated using the melt-drawn tapering method, and a polyacrylate/cryptophane-A film was deposited on the surface of the NATOF by drip-coating method. The sensor's response to transformer oil -dissolved methane was experimentally investigated. The results showed that the sensor exhibited a detection sensitivity of 9.8 pm/ppm for transformer oil-dissolved methane, with a detection limit of 2.35 ppm. Further-more, the sensor's excellent reversibility was validated through cyclic experiments. The sensor proposed in this paper can realize the in-situ detection of transformer oil-dissolved methane.

Automated summary

This paper proposed a methane sensor based on the evanescent field of the non-adiabatic tapered optical fiber (NATOF) for high-sensitivity in-situ detection of transformer oil-dissolved methane. The sensor exhibited a detection sensitivity of 9.8 pm/ppm and a detection limit of 2.35 ppm, with excellent reversibility validated through cyclic experiments.