弧光保护在10 kV开关柜中的应用

针对中低压配电柜内弧光故障的分布特点,进行弧光保护选型,确定弧光保护在开关柜内的安装位置和安装方法,为弧光保护的使用提供经验。     

High-voltage surge protection by a varistor-filled air gap

The electric discharge across a varistor granule filled air gap under a fast-rising voltage pulse was investigated for surge protection applications. The effects of temperature and pressure on the arc and the electrical conduction were analyzed by the characteristic changes in voltage waveforms triggered by a fast-rising high voltage pulse. In addition to the gap size, experimental results show that competing mechanisms among arc conduction, conduction through the varistor granule network, thermionic emission from Joule heating at granule-to-granule contact points, and the magnitude of the switching voltage dictate the maximum surge protection voltage for the filled air gap. Experimental evidence indicated that accumulated degradation was created at small contact points between varistor granules by repetitive assaults from longer duration, high voltage pulses. The uniqueness of using varistor over other dielectric granules in an air gap for surge protection is identified and discussed.     

中性点经小电阻接地风电场集电线路单相接地故障测距研究

风电场集电线路呈现多分支、多电源接入的形态。线路发生单相接地故障后,不同分支上风机依据感受到的电压降的不同而自动投入不同的低穿控制策略,从而会导致输出不同的分支电流,使得基于阻抗原理的测距方法失效。该文巧妙地利用风机箱变高压侧采用三角形接线的现实,无零序电流回路,提出基于故障区段逐次搜索的单相接地故障测距方法,并引入描述故障点弧光接地的对数电弧模型,实现了较高的测距精度。仿真算例和实际案例数据验证了算法的有效性。该算法可同时求解得到故障点电弧的长度,为后续的故障类型辨识奠定了基础。     

电弧喷涂枪的研究与设计

研究了喷涂电弧特点、喷嘴理论以及目前国内外最常用电弧喷涂枪的结构及其特点，提出了2种改进设计方案，最后介绍了电弧喷涂喷枪的最新发展状况。     

低能、高效非转移弧等离子喷枪特性的研究

研究利用计算机数值模拟技术，采用有限容积方法，针对自制的低能耗，高效率内送粉等离子喷涂设备，对其喷枪内部和外部区域等离子体的速度场，温度场以及放电特性进行模拟计算。研究结果表明采用计算机数值技术能够较准确模拟等离子有关特性，为更加准确必优化喷涂工艺过程打下基础。     

高速电弧喷涂镍铝打底层结构与性能研究

高速电弧喷涂技术是近年来发展起来的新型热喷涂技术，该技术具有优势，高效，低成本等特点，本文实验研究了高速电弧喷涂镍铝打底涂层的组织结构和力学性能，涂层的界面结合强度大于40MPa，显微硬度平均值为210HV，表面粗糙度表征参数Ra值为13．11um，涂层孔隙率为2．26％，涂层主要由镍铝合金和镍，铝氧化物组成，高速电弧喷涂镍铝涂层结合强度高，涂层组织致密，是优良的打底涂层。     

药芯焊丝电弧焊电弧形态与熔滴过渡行为的研究

基于数码照相技术研究了CO2保护气氛下,渣系和焊接参数对药芯焊丝电弧焊（FCAW）电弧形态和熔滴过渡行为的影响。研究发现,酸性及金属芯渣系药芯焊丝在所有焊接参数下电弧扩散角相差不大,碱性渣系药芯焊丝因药芯中含大量消电离元素,大焊接参数下电弧扩散角比其它两种渣系小;金属芯药芯焊丝大焊接参数下发生“半潜弧”,可见弧长显著缩短。随着焊接参数增大,酸性,碱性,金属芯药芯焊丝均依次出现如下熔滴过渡类型;短路过渡、大滴排斥过渡、细颗粒过渡,均未发生喷射过渡。     

A study on corrosion resistance characteristics of PVD Cr-N coated steels by electrochemical method

The corrosion behavior of Cr-N coated steels with different phases (-Cr, CrN and Cr₂N) deposited by cathodic arc deposition on AISI H13 steel was investigated in a 3.5% NaCl solution at ambient temperature. Potentiodynamic polarization tests, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were the techniques applied to characterize the corrosion behavior. It was found that the CrN coating had a lower current density from potentiodynamic polarization tests than others. The porosity, corresponding to the ratio of the polarization resistance of the uncoated and the coated substrate, was higher in the Cr₂N coating than in the other Cr-N coated steels. EIS measurements showed, for most of the Cr-N coated steels, that the Bode plot presented two time constants. Also, the Cr₂N coating represented the characteristic of Warburg behavior after 72 h of immersion. The coating morphologies were examined in planar view and cross-section by SEM analysis and the results were compared with those of the electrochemical measurement. The CrN coating had a dense, columnar grain-sized microstructure with minor intergranular porosity. From the above results, it is concluded that the CrN coating provided a better corrosion protection than the other Cr-N coated steels.     

弧焊逆变电源的输入性能分析与滤波电路参数优化

传统的逆变焊接电源对电网来说，本质上是一个带大电容的整流角载，其输入电流是一种尖角波，含有丰富的谐波分量。弧焊逆变电源的功率因数是畸变因子和位移因子的乘积，畸变因子表征了谐波畸变对功率因数的影响。为提高逆变电源的功率因数，必须采用谐波抑制技术降低输入电流的谐波畸变步。在弧焊逆变电源中采用LDC滤波电路，可以降低直流线上的电压纹波。通过优化参数设置，可以使弧焊逆变电源的功率因数提高到95%，电流谐波畸变率低到30%     

新型节能防触电交流弧焊机

提出一种用可控硅代替节能开关中的接触器的节能防触电交流弧焊机。该机引弧动作快,有较好的焊接适应性,为造船、建筑、桥梁和矿山等工业部门提供了较理想的交流弧焊机。