Quan Zhou

Electromagnetic environment of the EHV transmission line and its effect

Based on the characteristic of electromagnetic field around the EHV transmission line, this paper discusses the effect of electromagnetic environment of the EHV transmission line by analyzing power frequency electric field, magnetic field, radio interference and audio noises. Then this paper studies the lasting effect and transient electric breakdown effect by power frequency electric field to zoology, corona discharge to radio interference, power frequency magnetic field and audio noises to nearby environment. At last, example some limits rule and propose the steps to minish its effect to the environment by analyzing the transmission line electric field distribution rule and its affected factors.

Synthesis, characterisation and sensing properties of Sm2O3 doped SnO2 nanorods to C2H2 gas extracted from power transformer oil

In this paper, pure and 1.5, 2.5 and 3.5u200aat.-% samarium oxide (Sm2O3) doped tin oxide (SnO2) nanorods were successfully synthesised with a facile and environment friendly hydrothermal process. All the as prepared nanostructures were carefully characterised by X-ray diffraction, field emission SEM, TEM, high resolution TEM and X-ray photoelectron spectroscopy respectively. Planar sensors were further fabricated with the as synthesised samples, and their sensing properties towards acetylene gas (C2H2), an extremely significant fault characteristic gas dissolved in oil immersed power transformers, were systematically measured. Interestingly, the sensing properties of the fabricated SnO2 nanorod based sensor to C2H2 gas can be obviously enhanced by adding Sm2O3, and the sensor doped with 3.5u200aat.-%Sm2O3 displays the most superior sensing characteristics, including operating temperature, sensitivity, response and recovery time, etc., as compared to other three cases. All results indicate that the synthesised Sm2O3 doped SnO2 sensing material might be a promising candidate for C2H2 sensing and lay a solid foundation for exploring high performance chemical gas sensor to detect C2H2 gas extracted from power transformer oil.

NiO doped SnO2 p–n heterojunction microspheres: preparation, characterisation and CO sensing properties

Abstract We successfully synthesised pure and NiO doped SnO2 p–n heterojunction microspheres with different doping levels via a facile and environment friendly hydrothermal route. The crystalline structures, surface morphologies, element components and valences of the as synthesised nanostructures were characterised by means of X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy respectively. SnO2 based planar chemical gas sensors were fabricated from the as prepared samples, and their sensing performances towards carbon monoxide (CO) were systematically investigated. Compared with pure SnO2 sensor, NiO doped SnO2 microsphere sensors exhibit obviously enhanced CO sensing properties, such as higher gas response, lower operating temperature etc. It might be attributed to the p–n heterojunctions formed between p-type NiO and n-type SnO2 interfaces, further increasing the amount of absorbed oxygen ions and decreasing the activation energy of catalytic oxidation. The 3u200aat-%NiO doped SnO2 sensor demonstrates the highest response, quick response and recovery speed, good reproducibility and prominent stability against CO gas at an operating temperature of 260°C among the four sensors.

Breakdown characteristics of printed circuit boards under pulsed square wave

As the core component of the spacecraft power supply system, the safety and stability of Printed Circuit Boards (PCB) are very important for the whole spacecraft operation. However, PCB faces more insulation problems under abnormal operating conditions. On the one hand, miniaturization and high-density electrical devices result in continually decreasing insulation distance between PCB interconnection system, and the decreasing of insulation distance decreased the ability of resisting over voltage. On the other hand, PCB mainly affected by temperature, high vacuum under the abnormal operating conditions which accelerated aging of PCB. In this paper, the interconnection structure of PCB is designed and the effects of interconnection spacing, temperature, pressure and pulse width on the breakdown voltage of PCB are studied. The results indicated that the breakdown characteristics of PCB obey the Weibull distribution and the breakdown voltage of PCB with increasing interconnection spacing generally showed a linear increasing trend and with the increase of the pulse width, the breakdown voltage is decreased. With the increase of the temperature, the breakdown voltage is decreased. And the result also shows that the low pressure will weaken the insulation ability of the PCB.

Applying study on principle and method PD pattern recognition with fractal to profile of PD distribution

This paper adopts two kinds of fractal analysis to profile partial discharge (PD) distribution. The analysis results show that fractal dimension can be effectively used as a new feature in PD pattern recognition.

A novel electrical equipment on-line monitoring system based on geographic information system

Recently more and more single parameter electrical equipment on-line monitoring systems are being put into use. How to rationally fuse the on-line insulation monitoring information of this location dispersed equipment and thus to realize effective management of the on-line monitoring information from them and rationally analyze the specific electrical equipment are the questions which should be solved urgently. Geographic Information System (GIS) is used in this paper for the fusion of the on-line insulation information of the equipment within the different substations and different locations in the same substation and a multi-parameter method is used to analyze the insulation status of the specific electrical equipment. A novel electrical equipment on-line monitoring system with multi-parameters based on GIS is proposed, the means and steps for the construction of this system are explained through examples. Application results show that this method can overall reflect the running status of electrical equipment and greatly reduce the losses caused by sudden faults. Therefore, this method can meet the needs of modern management of power systems.