通过对某线110 k V有缺陷的线路避雷器进行绝缘电阻、泄漏电流及局放测试,并解体对其中泄漏电流不合格的电阻片进行干燥处理,干燥前后发现不合格的电阻片泄漏电流变化不大,为找出问题所在,提出通过测量避雷器电阻片电容量与额定值相比...通过对某线110 k V有缺陷的线路避雷器进行绝缘电阻、泄漏电流及局放测试,并解体对其中泄漏电流不合格的电阻片进行干燥处理,干燥前后发现不合格的电阻片泄漏电流变化不大,为找出问题所在,提出通过测量避雷器电阻片电容量与额定值相比较的方法,对不合格的电阻片进行电容量测量,测试结果显示:不合格的电阻片电容量均超过其额定值的20%,表明这些电阻片已经劣化,找出了造成该线路避雷器炸裂的原因并非电阻片受潮,而是电阻片本身劣化所致。展开更多
The evaluation of the mixing effect of gas-liquid two-phase flow during the top-blown gas agitation mixing is one of the difficulties in the testing field, especially in the process of using the model method to study ...The evaluation of the mixing effect of gas-liquid two-phase flow during the top-blown gas agitation mixing is one of the difficulties in the testing field, especially in the process of using the model method to study the metallurgical top-blowing process. In order to evaluate the effect of gas-liquid two-phase flow mixing, a gas chromatography simulation based on capacitance tomography was used to visualize the flow pattern and analyze the mixed characteristics. A gas top-blown agitation test rig was set up, the gas phase was air-selected, and the liquid phase was selected from synthetic heat-conducting oil. The top-blown stirring test process was measured and imaged by electrical capacitance tomography (ECT) equipment from ECT Instruments Ltd (UK). The MATLAB program was used to identify the mixing areas of the images to obtain the distribution of gas-liquid two-phase. The flow pattern of the gas-liquid mixing region was obtained. The chaotic detection of the gas-liquid mixing process was performed by the three-state test method;the images were processed by the counting box dimension-corrosion method to obtain the mixing uniformity time of gas-liquid flow. Results show that it is feasible to use the capacitance tomography technique to visualize the gas-liquid two-phase distribution. The uniformity time quantification of the gas-liquid mixing process is also achieved.展开更多
This paper presents a transimpedance amplifier （TIA） capacitance detection circuit aimed at detecting micro-capacitance, which is caused by ultrasonic stimulation applied to the capacitive micro-machined ultrasonic ...This paper presents a transimpedance amplifier （TIA） capacitance detection circuit aimed at detecting micro-capacitance, which is caused by ultrasonic stimulation applied to the capacitive micro-machined ultrasonic transducer （CMUT）. In the capacitance interface, a TIA is adopted to amplify the received signal with a center frequency of 400 kHz, and finally detect ultrasound pressure. The circuit has a strong anti-stray property and this paper also studies the calculation of compensation capacity in detail. To ensure high resolution, noise analysis is conducted. After optimization, the detected minimum ultrasound pressure is 2.1 Pa, which is two orders of magni- tude higher than the former. The test results showed that the circuit was sensitive to changes in ultrasound pressure and the distance between the CMUT and stumbling block, which also successfully demonstrates the functionality of the developed TIA of the analog-front-end receiver.展开更多
A self-sensing test method for the temperature of piezoelectric stack,based on the high correlation between the static capacitance and the stack temperature,is proposed in order to construct a self-sufficient methodol...A self-sensing test method for the temperature of piezoelectric stack,based on the high correlation between the static capacitance and the stack temperature,is proposed in order to construct a self-sufficient methodology of temperature measurement. Firstly,a theoretical model of static capacitance of the piezoelectric stack under preload was set up,and the influence of preload on the static capacitance was analyzed. Secondly,the correctness of the model was verified by static capacitance test experiments under various preloading conditions. Finally, the temperature measurement experiments at low-temperature stage for two kinds of piezoelectric stacks,namely the lowtemperature-resistant piezoelectric stack and conventional piezoelectric stack, were conducted under various preloading conditions using a polynomial fitting method. The results,which validate the accuracy of the test method,show that the maximum temperature deviations of the two kinds of piezoelectric stack are 3.9 ℃ and 2.8 ℃,respectively,when the preload force is close to the specified value. The test method uses the piezoelectric stack itself as a temperature sensor,which does not require additional equipment for temperature sensing,so that the space and equipment cost could be economized. And the test for static capacitance is concise and convenient,which indicates that in the cooling process,a concise and efficient test of the temperature of the piezoelectric stack could be realized so as to grasp the current temperature change in time.展开更多
文摘通过对某线110 k V有缺陷的线路避雷器进行绝缘电阻、泄漏电流及局放测试,并解体对其中泄漏电流不合格的电阻片进行干燥处理,干燥前后发现不合格的电阻片泄漏电流变化不大,为找出问题所在,提出通过测量避雷器电阻片电容量与额定值相比较的方法,对不合格的电阻片进行电容量测量,测试结果显示:不合格的电阻片电容量均超过其额定值的20%,表明这些电阻片已经劣化,找出了造成该线路避雷器炸裂的原因并非电阻片受潮,而是电阻片本身劣化所致。
基金Project(51666006) supported by the National Natural Science Foundation of ChinaProject(U1602272) supported by the Joint Funds of the National Natural Science Foundation of ChinaProject(2015HA019) supported by the Scientific and Technological Leading Talent Projects in Yunnan Province,China
文摘The evaluation of the mixing effect of gas-liquid two-phase flow during the top-blown gas agitation mixing is one of the difficulties in the testing field, especially in the process of using the model method to study the metallurgical top-blowing process. In order to evaluate the effect of gas-liquid two-phase flow mixing, a gas chromatography simulation based on capacitance tomography was used to visualize the flow pattern and analyze the mixed characteristics. A gas top-blown agitation test rig was set up, the gas phase was air-selected, and the liquid phase was selected from synthetic heat-conducting oil. The top-blown stirring test process was measured and imaged by electrical capacitance tomography (ECT) equipment from ECT Instruments Ltd (UK). The MATLAB program was used to identify the mixing areas of the images to obtain the distribution of gas-liquid two-phase. The flow pattern of the gas-liquid mixing region was obtained. The chaotic detection of the gas-liquid mixing process was performed by the three-state test method;the images were processed by the counting box dimension-corrosion method to obtain the mixing uniformity time of gas-liquid flow. Results show that it is feasible to use the capacitance tomography technique to visualize the gas-liquid two-phase distribution. The uniformity time quantification of the gas-liquid mixing process is also achieved.
基金Project supported by the National Natural Science Foundation of China(No.61127008)the Subsidized Program of the National High Technology Research and Development Program of China(No.2011AA040404)
文摘This paper presents a transimpedance amplifier （TIA） capacitance detection circuit aimed at detecting micro-capacitance, which is caused by ultrasonic stimulation applied to the capacitive micro-machined ultrasonic transducer （CMUT）. In the capacitance interface, a TIA is adopted to amplify the received signal with a center frequency of 400 kHz, and finally detect ultrasound pressure. The circuit has a strong anti-stray property and this paper also studies the calculation of compensation capacity in detail. To ensure high resolution, noise analysis is conducted. After optimization, the detected minimum ultrasound pressure is 2.1 Pa, which is two orders of magni- tude higher than the former. The test results showed that the circuit was sensitive to changes in ultrasound pressure and the distance between the CMUT and stumbling block, which also successfully demonstrates the functionality of the developed TIA of the analog-front-end receiver.
基金This work is supported by the NationalNatural Science Foundation of China （No. 11872207）；the Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX18_0266)the Fundamental Research Funds for the Central Universities(No.kfjj20180105)
文摘A self-sensing test method for the temperature of piezoelectric stack,based on the high correlation between the static capacitance and the stack temperature,is proposed in order to construct a self-sufficient methodology of temperature measurement. Firstly,a theoretical model of static capacitance of the piezoelectric stack under preload was set up,and the influence of preload on the static capacitance was analyzed. Secondly,the correctness of the model was verified by static capacitance test experiments under various preloading conditions. Finally, the temperature measurement experiments at low-temperature stage for two kinds of piezoelectric stacks,namely the lowtemperature-resistant piezoelectric stack and conventional piezoelectric stack, were conducted under various preloading conditions using a polynomial fitting method. The results,which validate the accuracy of the test method,show that the maximum temperature deviations of the two kinds of piezoelectric stack are 3.9 ℃ and 2.8 ℃,respectively,when the preload force is close to the specified value. The test method uses the piezoelectric stack itself as a temperature sensor,which does not require additional equipment for temperature sensing,so that the space and equipment cost could be economized. And the test for static capacitance is concise and convenient,which indicates that in the cooling process,a concise and efficient test of the temperature of the piezoelectric stack could be realized so as to grasp the current temperature change in time.
