PMMA based optical fiber Bragg grating for measuring moisture in transformer oil

W. Zhang*, D.J. Webb

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Water contamination can cause serious problems that compromise in transformer's safe operation and reduce its lifetime. Online monitoring of moisture concentration in transformer oil would permit the control of moisture buildup. This letter presents a direct optical measurement of moisture concentration in transformer oil using a poly(methyl methacrylate) (PMMA)-based optical fiber Bragg grating (POFBG). The refractive index and volume of PMMA-based optical fiber vary with the moisture in the surrounding transformer oil, changing the reflecting wavelength of the grating. A sensitivity of POFBG wavelength change to moisture content of 29 pm/ppm is demonstrated in this letter, indicating detectable water content better than 0.05 ppm.

Original languageEnglish
Pages (from-to)2427-2430
Number of pages4
JournalIEEE Photonics Technology Letters
Issue number21
Early online date4 Aug 2016
Publication statusPublished - 1 Nov 2016

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  • equilibrium relative humidity
  • Fiber Bragg gratings
  • moisture control
  • polymer optical fiber


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