不发生故障的

The effect of tribology factors on bearing vibration is studied experimentally. AR model and WPT are used to processing the normal arid abnormal signals. The results are as follows:1. The vibration of ball bearings is caused by the tribology action of contact pairs of ball and ring races and has the essential of tribo-dynamics. Any factors affecting the tribology characteristics of contact pairs will affect vibration and noise of bearings consequently.2. Vibration characteristics of bearing keep almostly unchanged with the increasing of axial load expecting the increasing of nature frequencies. When radial load increasing with axial load unchanged, nature frequencies keep unchanged but some new vibration peaks appears in the spectrum.3. Vibration amplitudes are damped and nature frequency are enhanced with sufficient lubrication. Vibration and noise of bearings increase obviously and roar can happen and the contact surfaces scratch slightly under insufficient and unclean lubrication state. Bearing will be disabled in a few minutes without any lubrication.4. Bearing vibration is unstable under low speed. With the speed increasing, the vibration become stable and natural frequencies increase slightly but the amplitudes increase apparently.5. Bearing vibration can be excited only by some harmonics ofwaviness without lubrication and by all harmonics with lubrication based on the theoretical analysis.6. The nature frequencies of ball bearings decrease with the increasing sizes. When international clearance increasing, nature frequencies decrease in radial and increase in axial and angular and the amplitudes increase in radial and decrease in axial and angular. When the number of balls increasing, nature frequencies increase and amplitudes decrease. When the pitch diameter increasing, axial nature frequency increase and others nearly keep no change. When outer race groove curvature radius increasing, nature frequencies increase in radial and decrease in axial and angular and amplitudes keep no change in radial and increase in axial and angular. When inner race groove curvature radius increasing, nature frequencies decrease and amplitudes increase.7. The distortion in amplitude and frequency components of bearing vibration signals picked up by the present probe measurement method is founded and right conclusions cannot be achieved by the signals. When accelerometer is rigidly screwed with steel stud onto a flat outer surface of a ball bearing, vibration signal can be got without distortion and the reliability of research on bearing vibration is assured.8. AR model is suitable for large samples of bearing vibration signals, square root of length of samples can be used as the upper limitation of order determination and the FPE order selection criterion is effective. Many advantages of AR spectrum are founded over the classical based on FFT.9. Time-Frequency analysis is necessary for abnormal noise of ball bearings. WPT overcomes the principle shortcomings of STFT and proved to be a best tool to process the abnormal signals.

理论分析和试验研究表明： 1球轴承振动是钢球—滚道接触副中的各种摩擦学作用引起的，具有摩擦动力学的本质，任何对接触副的摩擦学特性有影响的因素都将对球轴承的振动和噪声特性产生影响； 2中心轴向载荷作用下，载荷增大使球轴承的固有振动频率升高，载荷越大同样的载荷增幅引起的频率升幅减小，足够大的中心轴向载荷作用下载荷的变化对球轴承振动的频率特性不会产生明显的影响； 3轴向和径向联合载荷作用下，径向载荷不大时球轴承振动的固有频率基本不变，但是可能引起变刚度激励的非线性振动，出现新的频峰，过大的径向载荷将使部分钢球脱离接触，使球轴承的振动和噪声呈现不稳定状态； 4润滑对球轴承的振动和噪声特性有重要的影响，良好的润滑对振动有明显的抑制作用，润滑不充分时，振动和噪声的水平会有明显增高，一定条件下还会激发接触副中的谐振，发出啸声，造成接触表面的伤害，无润滑干接触时，短时的运转就会损伤接触副表面，使振动和噪声迅速增大，并随时可能引发严重的磨损和卡滞失效；接触副润滑良好时，油膜的"刚化效应"使球轴承振动的固有频率有所提高，润滑剂中含有弥散性污浊时，振动的幅度总体升高，但弥散性污浊不会改变球轴承振动的频率特性；浙江大学博士学位论文：球轴承振动的研究 5低速时，球轴承振动的基本特征呈现不稳定状态，随着转速的提高，球轴承振动的频率特性趋于稳定，固有频率频峰升高； 6理论分析表明，干接触时钢球和滚道表面波纹度的某些谐波分量能激励球轴承的振动，振动的幅值与谐波幅值成正比，实际球轴承中钢球的分布不可能完全均匀，波纹度的激励作用会随时发生；润滑接触的分析表明，波纹度的任意谐波分量均能激励球轴承的振动； 7球轴承的几何和结构参数分析表明，球轴承尺寸越大，径向、轴向和角振动的固有频率越低；钢球中心圆直径增大，球轴承的径向和轴向振动的固有频率基本不变，角振动的固有频率有所上升，振动的幅频特性基本不变；径向游隙加大使球轴承的径向振动固有频率降低，轴向和角振动的固有频率有所升高，径向振动幅频特性的幅值升高，而轴向和角向降低；钢球的数量增多使球轴承振动的固有频率上升，幅频特性的幅值下降，径向振动的幅值下降最为明显；外圈沟曲率半径系数增大使球轴承径向振动的固有频率升高，轴向和角振动的固有频率降低，径向幅频特性基本不变，轴向和角向幅频特性幅值升高；内圈沟曲率半径系数增大使径向、轴向和角振动固有频率均下降，振动幅频特性的幅值均有升高； 8试验对比表明，传感器采用探针式安装时，由于探针接触副接触特性的影响，钡(量得到的球轴承振动信号有失真，采用专门设计和制作的试验球轴承，以固定式安装加速度计，首次测量得到了球轴承振动的真实信号，通过对振动信号的分析，验证了球轴承振动的理论模型； 9)基于时间序列分析的AR模型适用于大样本球轴承振动信号的分析，以样本长度的均方根值作定阶上界，FPE做判阶准则，给出的AR谱光滑，频率分辨率高，是球轴承振动分析的简便而可靠的手段； 10以时频域分析的小波包变换分析球轴承异音信号能够比较好地定位和聚焦异音发生的时间，时间间隔，频率范围，同样是球轴承振动分析的可靠的手段，可用作球轴承故障诊断技术。

In future such failures are not likely to occur where there is dictatorship.

在今后这类故障是不太可能发生的，有专政。

The sensitivity of the proposed criterion is higher than that of the quondam criterion, and no floating threshold is used. It can judge the evolved fault quickly and correctly whether the power systems swing or not.

与目前所用的判别元件相比，该元件不需要采用浮动门槛，动作灵敏度较高，不受电力系统振荡的影响，能更准确有效地判断出系统是否发生了发展性故障。

In doing back-up data, we followed the work to be done is to switch to a system running DOS, and DOS command line in the implementation of "fdisk / mbr" command string to try to repair the hard disk of soft failure occurred ; if such a repair method to try is invalid, then we can go online to download and install the hard drive Bad Track professional testing tool to double-check the local hard disk in the phenomenon of the existence of Bad Track, Bad Track If you can not find the hard disk, it can not detect hard drive through the phenomenon is likely to be caused by the logic of failure, the logical solution is to find a Bad Track Repair Repair Tool to re-click the hard disk, only to do so.

在做好数据的备份工作后，我们接下来要做的工作就是将系统切换到DOS运行状态，并在DOS命令行中执行"fdisk /mbr"字符串命令，来尝试修复硬盘中发生的软故障；要是这种修复方法尝试无效的话，我们可以到网上下载安装一些专业的硬盘坏道检测工具，来仔细检查本地硬盘中是否存在坏道现象，如果找不到硬盘坏道的话，那硬盘检测无法通过的现象很可能是逻辑故障引起的，解决办法就是找逻辑坏道修复工具来重新修复一下硬盘，只能这样做了。

In doing back-up data, we followed the work to be done is to switch to a system running DOS, and DOS command line in the implementation of "fdisk / mbr" command string to try to repair the hard disk of soft failure occurred ; if such a repair method to try is invalid, then we can go online to download and install the hard drive Bad Track professional testing tool to double-check the local hard disk in the phenomenon of the existence of Bad Track, Bad Track If you can not find the hard disk, it can not detect hard drive through the phenomenon is likely to be caused by the logic of failure, when the only thing we can use the way is hard to find the logic of the corresponding brand Bad Track Repair Repair Tool to re-click the hard disk, I believe that case the hard disk will be able to detect the phenomenon can not be resolved the.

在做好数据的备份工作后，我们接下来要做的工作就是将系统切换到 DOS 运行状态，并在 DOS 命令行中执行" fdisk /mbr "字符串命令，来尝试修复硬盘中发生的软故障；要是这种修复方法尝试无效的话，我们可以到网上下载安装一些专业的硬盘坏道检测工具，来仔细检查本地硬盘中是否存在坏道现象，如果找不到硬盘坏道的话，那硬盘检测无法通过的现象很可能是逻辑故障引起的，此时我们唯一可以使用的办法就是找到对应品牌硬盘的逻辑坏道修复工具来重新修复一下硬盘，相信这么一来硬盘检测无法通过现象就能被解决了。

Pilot zero sequence directional protection may fail to operate because the zero sequence current on one end does not reach the set value of the protective relay,although zero sequence directional elements on both ends operate correctly.

线路发生接地故障时，两侧零序阻抗相差过大将导致两侧零序电流差别过大，虽然两侧的零序方向元件均能正确动作，但是由于一侧零序电流达不到动作定值，从而造成纵联零序方向保护拒动。

It has strong protection and prevent the inner arcing.

这对断路器室内发生内部故障是强有力的防范措施，绝对不会伤及人体。

As is known to all,because of the physical factor,the quality of electric component(such as transformer, generatrix,cable,power capacitor and motor),and the factor of maintenance. The fact of short circuit and abnormal running of the power supply system is inevitable.

众所周知，由于自然条件、电气元件（如变压器、母线、电缆、电力电容器、电动机等）制造质量、运行维护诸方面因素，供电系统发生短路故障或异常运行状态是不可能完全避免的。

Secondly, in spite of the reliability of software and control system, the mechanical system reliability of automatic yarn evenness tester is researched using FTA, and fault trees of each unit and system are established by analyzing its structure and function. According to system reliability theory and events probability, the mechanical system fault tree is analyzed by means of qualitative analysis and quantitative calculation, the system weak parts are found , and the ways are put forward to improve the mechanical system reliability.

其次，在不考虑软件及控制系统可靠性的情况下，利用故障树分析的方法，对全自动条干仪机械系统可靠性进行了分析研究，通过对其结构、功能的分析，建立了单个单元的故障树和系统的故障树；并根据系统可靠性的原理和事件发生的概率，进行了定性分析和定量计算，找出了系统的薄弱环节，提出了提高机械系统可靠性的途径。

At the same time, along with the increment of cities' railway transportation, it isharder and harder for the traditional protection equipments to distinguish the remote shortcircuit fault or the train starting correctly, especially for the fault with electricity arc ortransition resistance. This always results in the equipment operation time longer that it can'tcut off the short fault rapidly.

同时，随着城市轨道交通系统运量的不断加大，传统的保护装置越来越不能正确可靠地区分远端短路故障状态与机车起动状态，尤其是当发生远端电弧故障或经大过渡电阻故障时，往往造成保护动作时限加长。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。