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Journal of the Optical Society of Korea

Journal of the Optical Society of Korea


  • Vol. 14, Iss. 3 — Sep. 1, 2010
  • pp: 240–244

Current-induced Phase Demodulation Using a PWM Sampling for a Fiber-optic CT

Hyoung-Jun Park, June-Ho Lee, Hyun-Jin Kim, and Min-Ho Song  »View Author Affiliations

Journal of the Optical Society of Korea, Vol. 14, Issue 3, pp. 240-244 (2010)

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In this work, we used PWM sampling for demodulation of a fiber-optic interferometric current transformer. The interference signal from a fiber-optic CT is sampled with PWM triggers that produce a 90-degree phase difference between two consecutively sampled signals. The current-induced phase is extracted by applying an arctangent demodulation and a phase unwrapping algorithm to the sampled signals. From experiments using the proposed demodulation, we obtained phase measurement accuracy and a linearity error, in AC current measurements, of ~2.35 mrad and 0.18%, respectively. The accuracy of the proposed method was compared with that of a lock-in amplifier demodulation, which showed only 0.36% difference. To compare the birefringence effects of different fiber-optic sensor coils, a flint glass fiber and a standard single-mode fiber were used under the same conditions. The flint glass fiber coil with a Faraday rotator mirror showed the best performance. Because of the simple hardware structure and signal processing, the proposed demodulation would be suitable for low-cost over-current monitoring in high voltage power systems.

© 2010 Optical Society of Korea

OCIS Codes
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(060.5060) Fiber optics and optical communications : Phase modulation
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.5050) Instrumentation, measurement, and metrology : Phase measurement

Original Manuscript: May 11, 2010
Revised Manuscript: June 23, 2010
Manuscript Accepted: June 24, 2010
Published: September 25, 2010

Hyoung-Jun Park, June-Ho Lee, Hyun-Jin Kim, and Min-Ho Song, "Current-induced Phase Demodulation Using a PWM Sampling for a Fiber-optic CT," J. Opt. Soc. Korea 14, 240-244 (2010)

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