The Development Of Optical Fiber Current Sensor

With the development of the power system, the shortcomings of the traditional current meter are increasing obviously. For example, the traditional electromagnetic current transformer can not meet the needs of current measurement with high voltage, so, it is necessary to find a substitute. At the same time, the advantages of fiber-optic sensor technology are gradually increasing in the current measurement, thus, people place more importance on the optical fiber sensor technology used in the current measurement .In this thesis, the fiber-optic current sensor is based on fiber-optic sensor technology and takes optic-fiber as its transmission material, magneto-optic material which work followed the Faraday magneto-optic effect is took as its sensor component. The sensor has many strong point .such as: anti-electromagnetic interference, light weight, small size, wide bandwidth, low cost, stable construction, high sensibility and being easy to detect the current and to transmit signal , thus it is very useful for the current measurement in high voltage of the power system.In this thesis, sensor's research status, practical significance, background are briefly introduced. Then its category, working principle, process of design and production are also discussed in detail, the advantages and the disadvantages of these kinds of sensors are compared. According to the practical requirements and background of the subject, a kind of blocky fiber-optic current sensor is presented, and it is detailed in two aspects: optic-circuit design and electro-circuit design. In optic-circuit design, the optic source, by analyzing device sorts, feature and needs in system, the collimator, the light source and the polarimeter are chosen: In electro-circuit, laser driving circuit makes its stable output of optic source by light power feedback. Optic detecting and amplifying circuit makes the optoelectronic signals exchange, amplify, filter and get the voltage signals. Direct current circuit and alternating current circuit realize separately distilling of direct current and alternating current.Finally, the experimental system is designed and set up, the sensor is separately tested at different alternating current and the pulse current, then datum of sensor are compared with standard instrument and error is analyzed, according to these analysis ,the senor is improved and tested again. This experimental result indicates that sensor's performance parameters meet the design requirements completely.Range ability:50～34000 A ; Accuracy: 5%; Response time :< 10us.