光ファイバ電流センサの温度特性改善手法

概要

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This paper is described a method for improving temperature dependent properties of an intensity modulation type optical fiber current sensor for AC detection using flint glass fiber Faraday sensing element, which has been researched and developed by us. The sensor has highly advantageous properties such as light weight and flexible in various points of view, however, it also has a drawback that its output value is dependent on the ambient temperature where the sensor is installed. The ratio error in the sensor output value changes in the range of -0.4% to +1.2% corresponding to ambient temperature change of -20°C to +80°C. Its temperature dependent property is caused by the combined temperature dependence of a magnetic garnet crystal used in the sensor system and Faraday sensor fiber. We researched this temperature dependent mechanism and devised a gain adjusting method of the signal processing circuit amplifier to an optimum value to reduce the ratio error of the sensor. We verified that the ratio error was reduced remarkably with our method by experiment. The ratio error value obtained by the experiment was -0.1% to +0.2% in relation to ambient temperature change of -20°C to +80°C. This value met the highest accuracy standard for current transformers of protection relays required in JEC 1201-1PS class.
2010-04-01