The plasma current is modulated with an alternating current （ac） component in a frequency range of 90 Hz - 900 Hz in the plateau discharge phase in the CT-6B tokamak. A plasma electric conductivity profile in a form...The plasma current is modulated with an alternating current （ac） component in a frequency range of 90 Hz - 900 Hz in the plateau discharge phase in the CT-6B tokamak. A plasma electric conductivity profile in a form of （1 - r^2/a^2）^α with a parameter α which is fitted with the experimental data, can be determined. The effects of magnetic shear in a tokamak field configuration on the current penetration are taken into account in the numerical simulation. The measurement method and obtained results are discussed.展开更多
The induced electricity of 110 kV transmission lines which cross the UHV AC transmission lines may threaten personal safety of the maintenance staff. In this paper, field measurement of the induced voltage and induced...The induced electricity of 110 kV transmission lines which cross the UHV AC transmission lines may threaten personal safety of the maintenance staff. In this paper, field measurement of the induced voltage and induced current on a 110 kV crossing line inside Jinhua in Zhejiang province is performed. The electrostatic induced voltage on the measured line is 12.24 kV. The power frequency electromagnetic field simulation model is established, and the calculation results are consistent with the measured. Influence factors analysis shows that the electrostatic induced voltage on the 110 kV line is 12.78 kV, the electromagnetic induced voltage is 12.3 V, the induced current through ground wire is less than 1A when the UHV lines operate at full load. The induced voltage and current decrease while the crossing distance increases. Parallel lines induction is much higher than crossing lines. The electromagnetic induced voltage after ground knife-switch shut down would exceed the human safety voltage 36 V while the crossing angle is less than 30?, so the temporary ground wire must be hanged to ensure safety of the maintenance staff.展开更多
The design and performances of a high dynamic range DC-AC current sensor utilizing Giant Magneto-Impedance (GMI) are presented. The sensor is based on a GMI element with negative feedback. The sensing element is a 30 ...The design and performances of a high dynamic range DC-AC current sensor utilizing Giant Magneto-Impedance (GMI) are presented. The sensor is based on a GMI element with negative feedback. The sensing element is a 30 μm diameter GMI Co-based amorphous wire. It is curled to a toroidal core of 2 cm diameter. A bias magnetic field of about 650 A/m is applied to the GMI element to obtain an asymmetric GMI effect. A strong negative feedback is introduced to ensure linearity in a wide dynamic range. Analog conditioning electronics was fully developed. This includes a square wave oscillator based on an inverter trigger;a peak detector and a high gain amplifier with zero adjust. The GMI element is driven at a 3 MHz frequency and 5 mA peak-to-peak current. The closed-loop operations are investigated and the performances of the sensor are presented. DC current measurements are performed. The sensor exhibits good sensitivity and very good linearity, free from hysteresis, in a wide dynamic range of ±40 A. The sensitivity is about 0.24 V/A and the linearity error is about 0.02% of the full scale (FS). The hysteresis error is smaller than the measurement accuracy. AC current measurements using the developed sensor have also been successfully achieved. The sensor bandwidth in closed-loop was about 1.7 kHz.展开更多
铅酸蓄电池的SOH(State of Health)反映蓄电池的劣化程度,与蓄电池内阻是对应变化的关系。文中设计一种铅酸蓄电池内阻检测仪,基于交流阻抗法实现铅酸蓄电池内阻快速检测。交流恒流源产生正弦交流信号并注入到蓄电池;引入精密采样电阻,...铅酸蓄电池的SOH(State of Health)反映蓄电池的劣化程度,与蓄电池内阻是对应变化的关系。文中设计一种铅酸蓄电池内阻检测仪,基于交流阻抗法实现铅酸蓄电池内阻快速检测。交流恒流源产生正弦交流信号并注入到蓄电池;引入精密采样电阻,与蓄电池组成串联回路,将蓄电池及精密电阻两端产生的微弱响应信号经处理后送入单片机进行A/D转换,根据响应电压比值计算出蓄电池的内阻,并实时显示。为了验证此检测仪的性能,进行了实验验证,实验结果表明该仪器可有效检测铅酸蓄电池的内阻,反映蓄电池的SOH,区分新旧电池,检测结果稳定精确,具有一定的实际应用价值。展开更多
基金The project supported by the National Natural Science Foundation of China (Nos. 19789502 and 19889506)
文摘The plasma current is modulated with an alternating current （ac） component in a frequency range of 90 Hz - 900 Hz in the plateau discharge phase in the CT-6B tokamak. A plasma electric conductivity profile in a form of （1 - r^2/a^2）^α with a parameter α which is fitted with the experimental data, can be determined. The effects of magnetic shear in a tokamak field configuration on the current penetration are taken into account in the numerical simulation. The measurement method and obtained results are discussed.
文摘The induced electricity of 110 kV transmission lines which cross the UHV AC transmission lines may threaten personal safety of the maintenance staff. In this paper, field measurement of the induced voltage and induced current on a 110 kV crossing line inside Jinhua in Zhejiang province is performed. The electrostatic induced voltage on the measured line is 12.24 kV. The power frequency electromagnetic field simulation model is established, and the calculation results are consistent with the measured. Influence factors analysis shows that the electrostatic induced voltage on the 110 kV line is 12.78 kV, the electromagnetic induced voltage is 12.3 V, the induced current through ground wire is less than 1A when the UHV lines operate at full load. The induced voltage and current decrease while the crossing distance increases. Parallel lines induction is much higher than crossing lines. The electromagnetic induced voltage after ground knife-switch shut down would exceed the human safety voltage 36 V while the crossing angle is less than 30?, so the temporary ground wire must be hanged to ensure safety of the maintenance staff.
文摘The design and performances of a high dynamic range DC-AC current sensor utilizing Giant Magneto-Impedance (GMI) are presented. The sensor is based on a GMI element with negative feedback. The sensing element is a 30 μm diameter GMI Co-based amorphous wire. It is curled to a toroidal core of 2 cm diameter. A bias magnetic field of about 650 A/m is applied to the GMI element to obtain an asymmetric GMI effect. A strong negative feedback is introduced to ensure linearity in a wide dynamic range. Analog conditioning electronics was fully developed. This includes a square wave oscillator based on an inverter trigger;a peak detector and a high gain amplifier with zero adjust. The GMI element is driven at a 3 MHz frequency and 5 mA peak-to-peak current. The closed-loop operations are investigated and the performances of the sensor are presented. DC current measurements are performed. The sensor exhibits good sensitivity and very good linearity, free from hysteresis, in a wide dynamic range of ±40 A. The sensitivity is about 0.24 V/A and the linearity error is about 0.02% of the full scale (FS). The hysteresis error is smaller than the measurement accuracy. AC current measurements using the developed sensor have also been successfully achieved. The sensor bandwidth in closed-loop was about 1.7 kHz.
文摘铅酸蓄电池的SOH(State of Health)反映蓄电池的劣化程度,与蓄电池内阻是对应变化的关系。文中设计一种铅酸蓄电池内阻检测仪,基于交流阻抗法实现铅酸蓄电池内阻快速检测。交流恒流源产生正弦交流信号并注入到蓄电池;引入精密采样电阻,与蓄电池组成串联回路,将蓄电池及精密电阻两端产生的微弱响应信号经处理后送入单片机进行A/D转换,根据响应电压比值计算出蓄电池的内阻,并实时显示。为了验证此检测仪的性能,进行了实验验证,实验结果表明该仪器可有效检测铅酸蓄电池的内阻,反映蓄电池的SOH,区分新旧电池,检测结果稳定精确,具有一定的实际应用价值。
