This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put ...This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.展开更多
In-system programmable devices are products that combined modern electronic techniques and semiconductor techniques.They are indispensable devices in designing modern circuits and systems.This paper presents two pract...In-system programmable devices are products that combined modern electronic techniques and semiconductor techniques.They are indispensable devices in designing modern circuits and systems.This paper presents two practical circuits designed with programmable devices and its design method.By introducing programmable devices into gas sensor circuits,we can further improve system reliability,stability,sensitivity and integration degree,and enhance flexibility of system design.展开更多
With the rapid development of economy, strengthen the continuous construction of national infrastructure, etc., many industry demand for steel, steel enterprise capacity expands, at the same time, the steel enterprise...With the rapid development of economy, strengthen the continuous construction of national infrastructure, etc., many industry demand for steel, steel enterprise capacity expands, at the same time, the steel enterprises to positive response to the call of national energy conservation and emission reduction, using plant waste heat green development is the only way to realize the transformation and upgrading of the steel industry. This paper will be mainly for the domestic steel enterprise 6kV system short circuit current exceeds the limit and take the restrictive measures for detailed analysis and discussion for the industry reference.展开更多
To address the lack of voltage ratio standards for accuracy testing of low-frequency voltage transformers,it is necessary to develop a 3 kV low-frequency induction voltage divider.Firstly,based on the analysis of the ...To address the lack of voltage ratio standards for accuracy testing of low-frequency voltage transformers,it is necessary to develop a 3 kV low-frequency induction voltage divider.Firstly,based on the analysis of the error sources of the induction voltage divider,a method was proposed to calculate the excitation impedance of the induction voltage divider using complex magnetic permeability.A measurement circuit based on the lock-in principle was set up to measure the complex magnetic permeability of grained-oriented silicon steel 30P100 and permalloy 1J85 at different frequencies.Secondly,a 3 kV low-frequency induction voltage divider with a two-stage excitation and a series-wound ra-tio winding in 10 sections was designed.The errors of the two stages of the instrument transformers were calculated at 20 and 50 Hz,respectively.Finally,the divider's errors were calibrated at 20 and 50 Hz using the reference potential method.The results showed that,compared to 50 Hz,the excitation impedance of the two stages decreased and the errors increased at 20 Hz,with the overall error of the induction voltage divider being better at 50 Hz than at 20 Hz.Experimental measurements indicated that at 20 Hz,the ratio error and phase error of the 3 kV two-stage excitation induction voltage divider were better than 110-5,whereas at 50 Hz,the errors were better than 110-6.This study provides support for the accuracy testing of voltage transformers used in low-frequency flexible AC transmission projects.展开更多
文摘This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.
文摘In-system programmable devices are products that combined modern electronic techniques and semiconductor techniques.They are indispensable devices in designing modern circuits and systems.This paper presents two practical circuits designed with programmable devices and its design method.By introducing programmable devices into gas sensor circuits,we can further improve system reliability,stability,sensitivity and integration degree,and enhance flexibility of system design.
文摘With the rapid development of economy, strengthen the continuous construction of national infrastructure, etc., many industry demand for steel, steel enterprise capacity expands, at the same time, the steel enterprises to positive response to the call of national energy conservation and emission reduction, using plant waste heat green development is the only way to realize the transformation and upgrading of the steel industry. This paper will be mainly for the domestic steel enterprise 6kV system short circuit current exceeds the limit and take the restrictive measures for detailed analysis and discussion for the industry reference.
基金The Innovation Fund Project of China Electric Power Research Institute:Research on accuracy test method of voltage transformer for low-frequency transmission and development of test system,Grant/Award Number:GY83-22-005。
文摘To address the lack of voltage ratio standards for accuracy testing of low-frequency voltage transformers,it is necessary to develop a 3 kV low-frequency induction voltage divider.Firstly,based on the analysis of the error sources of the induction voltage divider,a method was proposed to calculate the excitation impedance of the induction voltage divider using complex magnetic permeability.A measurement circuit based on the lock-in principle was set up to measure the complex magnetic permeability of grained-oriented silicon steel 30P100 and permalloy 1J85 at different frequencies.Secondly,a 3 kV low-frequency induction voltage divider with a two-stage excitation and a series-wound ra-tio winding in 10 sections was designed.The errors of the two stages of the instrument transformers were calculated at 20 and 50 Hz,respectively.Finally,the divider's errors were calibrated at 20 and 50 Hz using the reference potential method.The results showed that,compared to 50 Hz,the excitation impedance of the two stages decreased and the errors increased at 20 Hz,with the overall error of the induction voltage divider being better at 50 Hz than at 20 Hz.Experimental measurements indicated that at 20 Hz,the ratio error and phase error of the 3 kV two-stage excitation induction voltage divider were better than 110-5,whereas at 50 Hz,the errors were better than 110-6.This study provides support for the accuracy testing of voltage transformers used in low-frequency flexible AC transmission projects.
