Analysis of Gear Breakage and Countermeasures Based on Fault Tree

Gears are important parts of mechanical products and have been widely used in various industries.A spur gear was broken early in a transmission chain.This article starts with the breakage fault of the gear.The processes of fault analysis and improvement countermeasure were comprehensively sorted out based on fault tree,and the relevant influencing factors which affect the life of gears were examined one by one.Through detailed investigation,the abnormal high load on the gears was clarified.The gear design strength reserve did not meet the requirements for customer-specific operating conditions,and further improvements had been made.By optimizing the oil-filling characteristics and timing matching of the hydraulic system,the impact of shift shock was reduced,thereby reducing the load on the gears.At the same time,by increasing the pressure angle of the gear,the gear strength margin was increased from the design point of view.Through the fatigue test on the bench,the gears worked safely.After further verification of the actual vehicle test,the gears worked safely and normally,so the improvement measures were effective.This article provides a useful reference for trouble shooting processes and a problem solving method for similar faults through detailed analysis of factors affecting gear life.

Dynamic Fault Model for On-Line Evaluation of Yarn End Breakage during Ring Spinning

In this paper, a dynamic fault model is proposed to predict yarn end breakage in the spinning procedure through investigation of fault characteristics. In view of the principle that uniformity bad in raw material causes iustable yarn formation, the investigation focuses on the fault characteristic existing in the dynamic tension. Analyzing the dynamic spinning system, the phenomenon of over random shock in a spinning triangle is discovered to be the main physical event prior to yarn end breakage. The fault characteristic is further confirmed by dynamic tests and signal processing, and can be used to make an approach to predicting yarn end breakage. A relative energy feature is defined for evaluating the tendency of yarn end breakage, and its effectiveness is verified by on.line monitoring tests in the laboratory. The research results show that the proposed dynamic fault model has not only an advantage in indicating the presence of fault characteristics, but also great potentials in quantitating fault in online spinning monitoring.

Single-phase earth fault current distribution between optical fiber composite overhead ground wire and ordinary ground wire in transmission system

It is important for the safety of transmission system to accurately calculate single-phase earth fault current distribution.Features of double sided elimination method were illustrated.Quantitative calculation of single-phase earth fault current distribution and case verification were accomplished by using the loop method.Influences of some factors,such as single-phase earth fault location and ground resistance of poles,on short-circuit current distribution were discussed.Results show that:1) results of the loop method conform to those of double sided elimination method;2) the fault location hardly influences macro-distribution of short-circuit current.However,current near fault location is evidently influenced;and 3) the short-circuit current distribution is not so sensitive to the ground resistance of poles.

基于改进极模变换的柔性直流输电系统断线故障分析与辨识

断线故障的故障特性分析是制定断线保护方案的基础。首先,文中以金属回线双极直流系统为对象,根据直流系统中模块化多电平换流器(MMC)在故障前后的状态变化,基于叠加定理得出MMC在直流系统发生故障时的等效电路模型,构建直流系统断线故障下的等效电路。然后,通过改进极模变换矩阵推导其在不同故障类型下的复合模量等值网络,分析不同断线故障的模量特征;在此基础上,利用2模和0模电流的变化量构建断线故障类型识别的相平面,实现断线故障的分类;同时,提出基于1模电流变化量的区内外断线故障辨识流程。最后,在PSCAD/EMTDC中建立了仿真模型,验证了所提保护方法的快速性和可靠性。

兼顾短路与断线故障识别的柔性直流电网行波保护方案

目前大多数柔性直流电网行波保护在配置时仅考虑短路故障,当发生断线故障时,保护动作的正确性尚不明确。对此,首先分析了断线故障下传统行波保护的动作特性,得出了传统行波保护无法正确识别短路与断线故障的结论。在此基础上,探索了断线与短路故障下线路受端的第二个电流波头特征和线路电压特征,研究了两种故障下线路送端的电流首行波特征以及两端电压与电流变化量乘积的特征,提出了一种兼顾短路与断线故障识别的行波保护方案。基于PSCAD/EMTDC仿真平台对所提保护方案进行了性能验证。结果表明,该保护方案能准确识别并应对各种条件的故障,且具有较高的速动性和抗噪声干扰能力。

跨活断层隧洞抗错断技术模型试验研究

长大隧洞工程不可避免地要跨越活动断裂带及其影响区域,为减少因断层错动而导致的隧洞结构破坏,抗错断设计是隧洞设计的重要内容。以滇中引水工程香炉山隧洞为背景,对包括铰接设计、扩挖-缓冲层设计以及铰接-扩挖-缓冲层在内的3种抗错断措施进行模型试验研究;从衬砌内部破坏、隧洞整体破坏、衬砌应变方面,对上述3种抗错断措施抗断效果进行了验证评估。研究结果表明:(1)从隧洞衬砌结构内部破坏特征来看,铰接设计与扩挖-缓冲层设计都可以对衬砌起到保护作用。(2)从隧洞整体变形和裂纹分布来看,使用铰接设计增大了隧洞在断层带区域的变形程度,但减小了衬砌本身的破坏;使用扩挖-缓冲层设计不仅减小了隧洞在断层带区域的变形,同时也相对减小了对衬砌本身的破坏,经铰接-扩挖-缓冲层设计的隧洞变形几乎只出现在铰接处,衬砌破坏更小。(3)从隧洞纵向应变分布规律来看,扩挖设计和铰接设计都减小了衬砌的应变,其中铰接设计对衬砌应变的减弱最为突出。相关研究成果可为跨活断裂隧洞实际工程中抗错断方案的选用提供参考。

高速线材精轧锥辊箱故障诊断分析

针对某钢厂高速线材产线精轧区域锥辊箱振动问题,通过在线监测系统及时定位锥辊箱缺陷位置,准确判断劣化程度。对锥辊箱振动全过程进行了分析总结,并对在以后的振动分析时遇到类似的振动信号应考虑的问题提出一定见解。

Fast Single-phase Fault Location Method Based on Community Graph Depth-first Traversal for Distribution Network

With the increasing complexity of distribution network structures originating from the high penetration of renewable energy and responsive loads,fast and accurate fault location technology for distribution networks is a prerequisite for rapid isolation of faults and restoration of the power supply.In this paper,a fault location method based on community graph depth-first traversal is proposed for fast location of single-phase ground faults in distribution networks.First,this paper defines the fault graph weight of the vertices in the distribution network graph model,which can be used to reflect the topology of the vertices and fault points as well as the fluctuation of the vertices’currents.Then,the vertices on the graph model are clustered by using an improved parallel louvain method(IPLM).Finally,the community formed by IPLM is used as the smallest unit for depth-first traversal to achieve fast and accurate location of the fault section.The paper develops a distribution network graph model of IEEE 33-bus system on the graph database for testing.And three other methods are selected for comparison with IPLMDF.The test results show that IPLMDF can achieve fast and accurate fault location when half of the nodes in the distribution network are equipped with D-PMUs.When some of the D-PMUs lose time synchronization,it is still possible to locate the fault section,and at the same time,the locating results can be avoided by falling into local optimal solutions.

断层区煤巷顶板破断问题与支护研究

为解决煤巷断层区顶板破断引起的冒顶事故,在简述该事故危害的基础上,对其产生原因、机制进行深入分析,然后提出相应的支护对策,为相关人员提供参考,有效预防断层区煤巷顶板破断冒顶事故发生。

刮板输送机卡、断链张力分析

断链故障主要是由链环所受张力突增导致材料出现塑性变形和开裂。采用ADAMS仿真软件对刮板输送机不同位置断链后机头、机尾附近的张力响应进行仿真分析,得到刮板输送机链传动过程中断链前极限张力,为刮板输送机优化设计提供了参考。

高速列车齿轮传动系统断齿故障非线性动力学特性研究

高速列车齿轮传动系统在实际的工作环境中可能出现轮齿磨损、折断等各种故障,这将造成齿轮传动稳定性下降,甚至造成齿轮传动失效,危及列车运行安全。文章以考虑断齿故障的高速列车齿轮传动系统为研究对象,通过数值模拟,揭示了断齿故障幅值与激励频率协同作用下的系统分岔特性;研究表明:断齿故障使齿轮传动系统的动力学行为演化变得更加复杂,特别是对周期运动的影响比较突出;与无故障状态相比,系统的单周期运动受断齿故障影响而向多周期、概周期转变,但在混沌区域上,故障对系统动力学特性的影响并不明显;研究结论可为复杂环境下运行的齿轮系统设计和参数优化提供参考。

鼠笼异步电机多故障智能诊断基本研究

围绕鼠笼式异步电动机的结构、工作原理及其多故障智能诊断技术进行了深入研究。介绍了鼠笼电机的构造和基本工作原理,包括其定子和转子的主要组成部分,以及电机的起动和运行机制。分析了鼠笼电机可能出现的机械和电气性质故障,如转子断条和轴承故障,并推导了相应的故障特征频率分量,阐述了其在故障诊断中的作用。指出了鼠笼电机故障诊断的难点和现有技术的局限性,并提出了基于参数测定和机器学习技术的智能诊断方法。强调了智能故障诊断技术在保障工业生产连续性和安全性方面的重要性,并展望了未来的研究方向和技术发展。

一种涂胶封装半导体绑定金线断裂失效原因分析及改善方法

在半导体封装工艺中,芯片键合是非常关键的一环,其中绑定是芯片键合的一种普遍方式,它用高纯度金线把芯片接口和基板接口键合,从而实现信号的传输和电气连接[1]。然而使用过程中绑定容易出现一些故障,金线断裂是绑定常见的故障原因之一。本文通过对一种PCBA上涂有防护胶的传感器进行不良解析,采用故障树梳理金线断裂的可能因素,结合CT扫描、金线断面SEM对比分析等方式,找出金线颈部断裂的根本原因并提出改善方法,为金线断裂分析提供了一种有效的解析方式。

异步电动机的转子断条问题研究

讨论了异步电动机转子断条故障的特征机理,介绍了通过定子电流监测进行故障诊断的方法。概述了鼠笼式异步电动机转子断条故障可能由机械应力、过载电流和设计缺陷等因素引起,并强调了这种故障对电机性能的负面影响,包括转速异常、噪声增大和潜在的安全风险。提出了通过监测气隙磁场变化和定子电流频谱分析来诊断故障的方法。在正常情况下,电机磁动势平衡对称,而转子断条破坏了这种对称性,导致转矩波动和平均转矩下降。通过对定子电流进行频谱分析,检测到特定的谐波分量。提出结论,尽管传统理论侧重于基波的影响,实际上其他定子电流成分也参与了谐波的生成,并且可以通过监测特定频率的谐波分量来判断转子是否存在断条故障。

Fault Line Selection Method Considering Grounding Fault Angle for Distribution Network

In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.

一起220kV GIS三工位隔离开关故障原因分析

某220 kV变电站220 kV GIS设备进行回路电阻测试试验时,三工位隔离开关的A相接地开关无法合闸,经现场排查为A相传动齿轮箱故障所致。将A相传动齿轮箱进行解体检查,发现箱内的换向锥形齿轮轴发生断裂。利用理化分析手段对锥形齿轮轴的断裂原因进行了试验分析,结果表明,传动齿轮箱盖板密封圈不配套致使箱内进水,造成齿轮轴传动部位锈蚀卡涩;同时,承担换向及承载的锥形齿轮轴键槽机加工及热处理不规范,使得键槽根部未有效圆角过渡的应力集中部位在操动机构反复动作形成的循环载荷及锈蚀卡涩产生的大的应力作用下产生疲劳开裂引发的整体断裂,致使无法传递载荷,进而导致传动齿轮箱及操动机构的故障。

暂态方向法对配电网单相断线不接地故障的适应性分析

暂态方向法广泛应用于单相接地故障检测,明确其对单相断线故障的适应性可指导单相断线故障检测方法的研究。本文首先推导了单相断线不接地故障下电源侧和负荷侧的零序电压幅值特征,分析了启动判据的适应性,在此基础上分析了暂态零序电压和零序电流的分布特征,给出了暂态方向法的适应性。理论分析和仿真验证表明零序电压启动判据存在死区,而零序电压满足启动判据的情况下暂态方向法可适用于单相断线不接地故障的检测。

计及干摩擦的风电齿轮断齿故障动力学分析

为了揭示齿面摩擦影响风电齿轮传动系统中定轴齿轮断齿故障动力学行为变化的机理,基于库伦摩擦定律,计算定轴轮系和行星轮系轮齿间的齿面摩擦力。通过改变齿宽模拟断齿故障,应用势能法得到定轴齿轮断齿后的时变啮合刚度;考虑干摩擦、时变啮合刚度、传递误差、齿侧间隙和阻尼,建立含一级定轴齿轮断齿故障的风电齿轮传动系统动力学模型;通过分析一级定轴齿轮啮合点的相对位移随系统啮合频率变化的分岔图、相图和Poincare截面,研究定轴齿轮的动力学特性。结果表明,齿面摩擦在高频区域对系统的分岔形式较为明显,相图和Poincare截面的形状复杂多变,系统混沌区间增加,加剧了断齿对系统稳定性的影响。

基于权重修正D-S理论多判据融合的含新能源低压配网中性线断线判别方法

中性线断线故障的识别与定位对低压配电网的故障诊断有重要作用。但传统基于电流或电压故障特征量的断线检测方法会因负载的波动和其不平衡度的大小而导致漏判误判,并且随着大规模分布式新能源的接入,故障特征随着低压配电网拓扑结构的改变而改变,传统故障识别判据不再精确有效。为此,在考虑新能源接入的情况下提出了一种基于权重修正D-S理论多判据融合的中性线断线检测方法。根据中性线断线故障特性的分析结果,分别对基于中性线电流和三次谐波电流变化的电流故障特征判据以及基于中性点偏移电压的电压故障特征判据进行改进,修正新能源接入对多种判据带来的影响。最后基于动态临近历史数据的判断结果,采用权重修正D-S证据理论将改进电流、电压多个判据信息进行融合,形成中性线断线故障综合判据。该方法能够提高对不同场景的适应度,并解决传统检测带来的误判问题。仿真结果验证了该方案的有效性。

基于PLC的电梯起重机机械钢丝绳断裂故障监测系统

为了准确监测电梯起重机机械钢丝绳断裂故障,提出一种基于PLC的电梯起重机机械钢丝绳断裂故障监测系统。通过PLC的逻辑判断功能完成系统硬件组态以及网络结构的创建,分析不同模块的功能。同时采集电梯起重机机械钢丝绳数据,通过单一传感器独立输出信号,对采集的信号消噪处理,提取电梯起重机机械钢丝绳断裂故障信号,最终完成故障监测。经实验测试证明,所提方法可以获取高精度的故障监测结果。