The work principle of all fiber optical current transducer (AFOCT) was introduced. By analyzing the characteristic of photo-detector's output, a measurement and signal processing scheme based on sine wave modulati...The work principle of all fiber optical current transducer (AFOCT) was introduced. By analyzing the characteristic of photo-detector's output, a measurement and signal processing scheme based on sine wave modulation and demodulation was put forward for eliminating the influence of light intensity change and modulation degree change. A digital signal processing system and a calibration scheme were also advanced. The experimental data show that the mean ratio error is 0.016 74% for direct current and 0.035% for alternating current, and the correlation coefficient of linearity is up to 0.999 982 4, meeting the precision requirement of 0.2 grade. Stability experiments and temperature drift experiments show the AFOCT has a better stable capability.展开更多
The paper proposes an experimental method of material inspection,which is based on digital processing of multi-frequency eddy current measurement data.The influences of various factors(conductivity,the gap between the...The paper proposes an experimental method of material inspection,which is based on digital processing of multi-frequency eddy current measurement data.The influences of various factors(conductivity,the gap between the sample surface and the sensor,the thickness of the sample) on the obtained hodographs are examined by taking the aluminum alloys for example,and the possibility of separation of various factors is analyzed.The results obtained are indicative of how much promise the proposed method offers for the inspection and testing of products made of aluminum alloys.展开更多
设计了一种新型光纤电流互感器(Optical fiber Current Transformer,简称OCT),采用光纤传感技术与电子技术相结合的方法,研制出电压等级为110kV,额定电流为1kA的样机。该样机已经通过有关测试,其精度达到±0.2%。与传统的电流互感...设计了一种新型光纤电流互感器(Optical fiber Current Transformer,简称OCT),采用光纤传感技术与电子技术相结合的方法,研制出电压等级为110kV,额定电流为1kA的样机。该样机已经通过有关测试,其精度达到±0.2%。与传统的电流互感器相比,这种新型光纤电流互感器具有精度高、体积小、造价低、良好的动态特性和不受电磁干扰等优点。展开更多
在用涡流检测(Eddy Current Testing,ECT)法评价设备缺陷时,缺陷信号由于受到探头提离及设备结构变化引起的非缺陷信号及环境噪声的影响而恶化,直接影响到对缺陷的正确评估。采集了自然裂纹ECT信号并根据其特点,采用小波变换对其进行了...在用涡流检测(Eddy Current Testing,ECT)法评价设备缺陷时,缺陷信号由于受到探头提离及设备结构变化引起的非缺陷信号及环境噪声的影响而恶化,直接影响到对缺陷的正确评估。采集了自然裂纹ECT信号并根据其特点,采用小波变换对其进行了去噪处理。首先将ECT信号进行小波分解,去除非缺陷信号及白噪声信号分量,然后对小波系数进行反变换,重构缺陷信号。对一维和二维ECT信号处理结果表明这种信号处理技术对提取湮没在非缺陷信号和白噪声中的缺陷信号非常有效。展开更多
文摘The work principle of all fiber optical current transducer (AFOCT) was introduced. By analyzing the characteristic of photo-detector's output, a measurement and signal processing scheme based on sine wave modulation and demodulation was put forward for eliminating the influence of light intensity change and modulation degree change. A digital signal processing system and a calibration scheme were also advanced. The experimental data show that the mean ratio error is 0.016 74% for direct current and 0.035% for alternating current, and the correlation coefficient of linearity is up to 0.999 982 4, meeting the precision requirement of 0.2 grade. Stability experiments and temperature drift experiments show the AFOCT has a better stable capability.
基金supported by Program for Basic Scientific Research of the State Academies of Sciences for 2013e2020the RF Ministry of Education and Science (Contract No. 02.G25.31.0063)
文摘The paper proposes an experimental method of material inspection,which is based on digital processing of multi-frequency eddy current measurement data.The influences of various factors(conductivity,the gap between the sample surface and the sensor,the thickness of the sample) on the obtained hodographs are examined by taking the aluminum alloys for example,and the possibility of separation of various factors is analyzed.The results obtained are indicative of how much promise the proposed method offers for the inspection and testing of products made of aluminum alloys.
文摘设计了一种新型光纤电流互感器(Optical fiber Current Transformer,简称OCT),采用光纤传感技术与电子技术相结合的方法,研制出电压等级为110kV,额定电流为1kA的样机。该样机已经通过有关测试,其精度达到±0.2%。与传统的电流互感器相比,这种新型光纤电流互感器具有精度高、体积小、造价低、良好的动态特性和不受电磁干扰等优点。
文摘在用涡流检测(Eddy Current Testing,ECT)法评价设备缺陷时,缺陷信号由于受到探头提离及设备结构变化引起的非缺陷信号及环境噪声的影响而恶化,直接影响到对缺陷的正确评估。采集了自然裂纹ECT信号并根据其特点,采用小波变换对其进行了去噪处理。首先将ECT信号进行小波分解,去除非缺陷信号及白噪声信号分量,然后对小波系数进行反变换,重构缺陷信号。对一维和二维ECT信号处理结果表明这种信号处理技术对提取湮没在非缺陷信号和白噪声中的缺陷信号非常有效。