Suehiro & Nakano Lab.

Diagnosis of gas insulated switch gear using carbon nanotube gas sensor

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Gas-insulated switchgear (GIS), which is filled with pressurized SF6 gas for electrical insulation as well as for arc extinction, is widely used in electric power system in recent decades due to the compact size and high reliability. Despite the high reliability, insulation fault may still occur in the long lifetime of GIS (typically a few tens of years). So it is important to predict and avoid potential insulation fault in GIS. Partial discharge (PD) detection is an effective method to assess the insulation condition of GIS. To date, several PD detection methods have been proposed and investigated, such as an ultra-high frequency electro-magnetic field sensor, an acoustic emission sensor, an optical emission sensor and a chemical byproducts analysis.

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One advantage of the chemical byproducts analysis is that it is not affected by electromagnetic background noises. It is well known that SF6 will undergo some decomposition under discharge and overheating. SF4, SOF2, SO2, SOF4, SO2F2, F2 and HF are generated as a result of SF6 decomposition and the reactions with contaminants such as water vapor and oxygen. These chemical byproducts can be an indicator of PD and detected by various methods including a gas detection tube, a gas chromatography and FTIR. Recently, carbon nanotube (CNT) gas sensors have received considerable attention because of their outstanding properties, such as quicker response, higher sensitivity, lower operating temperature and wider variety of gases that may be detected compared with the other types of gas sensors.

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We proposed a new detection method of PD occurring in SF6 using a carbon nanotube (CNT) gas sensor, which was fabricated by a new method based on electrokinetic manipulation of CNTs under positive dielectrophoresis (DEP), which trapped CNTs onto the microelectrode. When PD was generated in SF6, the electrical conductance of gas sensor gradually increased. FTIR analysis and molecular orbital calculations revealed that major decomposition products, which were responsible for the CNT sensor response were SF4 and SOF2.

Further readings

  1. Chemical detection of SF6 decomposition products generated by AC and DC corona discharges using a carbon nanotube gas sensor
    Advanced Materials Research, Volume 699, 2013, Pages 909-914
    R. Shou, K. Hata, M. Nakano and J. Suehiro
    abstract
    　
  2. Detection of SF6 decomposition products generated by DC corona discharge using a carbon nanotube gas sensor
    IEEE Transactions on Dielectrics and Electrical Insulation, Volume 19, Issue 2, April 2012, Article number 6180262, Pages 671-676
    Y. Martin, Z. Li, T. Tsutsumi, R. Shou, M. Nakano, J. Suehiro and S. Ohtsuka
    abstract
    　
  3. Response of a carbon nanotube gas sensor to impulse discharges in SF6 gas
    IEEJ Transactions on Fundamentals and Materials, Volume 132, Issue 11, 2012, Pages 978-979
    R. Shou, T. Tsutsumi, M. Nakano and J. Suehiro
    abstract
    　
  4. Identification of DC corona generating SF6 decomposition gases adsorbed on CNT gas sensor using FTIR spectroscopy
    Proceedings of TENCON 2010 - 2010 IEEE Region 10 Conference, 2010, pp. 663-666
    Y. Martin, Z. Li, T. Tsutsumi, J. Suehiro, K. Imasaka and S. Ohtsuka
    abstract
    　
  5. Factors affecting PD detection in GIS using a carbon nanotube gas sensor
    IEEE Transactions on Dielectrics and Electrical Insulation, Volume 14, Issue 3, June 2007, Pages 718-725
    W. Ding, K. Ochi, J. Suehiro, K. Imasaka, R. Hayashi and M. Hara
    abstract
    　
  6. Analysis of PD-generated SF6 decomposition gases adsorbed on carbon nanotubes
    IEEE Transactions on Dielectrics and Electrical Insulation, Volume 13, Issue 6, December 2006, Pages 1200-1207
    W. Ding, R. Hayashi, K. Ochi, J. Suehiro, K. Imasaka, M. Hara, N. Sano, E. Nagao, and T. Minagawa
    abstract
    　
  7. Calibration methods of carbon nanotube gas sensor for partial discharge detection in SF6
    IEEE Transactions on Dielectrics and Electrical Insulation, Volume 13, Issue 2, April 2006, Pages 353-361
    W. Ding, R. Hayashi, J. Suehiro, G. Zhou, K. Imasaka and M. Hara
    abstract
    　
  8. Detection of partial discharge in SF6 gas using a carbon nanotube-based gas sensor
    Sensors and Actuators B: Chemical, Volume 105, Issue 2 , 28 March 2005, Pages 164-169
    J. Suehiro, G. Zhou and M. Hara
    abstract
    　
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