如何检修复印机人为故障

所谓人为故障是指由于误操作、乱拆、乱卸、不合理保养以及检修失误等因素引起的机器故障。维修人员在日常的维修工作中经常会遇到一些别人或自己造成的人为故障,检修起来深感不便,对于这类敖障的检修方法,笔者试举两个实例进行分析,望能起到与同行     

SUN—2型事故记录仪使用中出现的问题浅析及改进措施

1 前言 为提高机组的故障监视水准,加强事故现场记录,以便更迅速地排除机组的故障及故障的潜在因素,为区别各种人为故障因素和非人为故障因素提供客观依据,目前,一般机组均采用事故记录仪进行事故动作记录,以提高机组安全运行水平。韶关电厂#3、#4、#5、#6等4台5万千瓦机组以及#8机组所采用事故记录仪均系天津宝坻海河     

电网故障恢复系统简介

电网故障是电力系统不可避免的，对于简单的电网故障可以通过人为恢复，但对于复杂的电网故障，如果通过人为恢复，需要很长的恢复时间，即使最简单的电网，人为恢复也需要一定的时间，为此提出建立电网故障恢复系统。下面就简单谈谈电网故障恢复的一般过程和基本结构。     

浅析UPS日常维护中的人为故障

根据日常维护中接触的一些案例，针对UPS在人为故障方面的一些事项进行了归类分析，提出了正确使用和维护UPS的方法及应避免的人为故障。     

基于单侧信息的多分支配网单相接地故障定位

单相接地故障是配电网中最常见的故障类型,但查找发生在带分支配电线路中的单相接地故障点比较困难。针对该问题,通过在线路最长分支末端健全相设置人为接地点,将单相接地故障转化为两相接地故障,在人为接地相回路电压方程的基础上推导了故障区段预判算法,在故障相回路电压方程的基础上推导了故障测距算法,并提出了故障区段预判结果检验和校正算法。理论推导和MATLAB/Simulink仿真实验证明了上述算法最终定位误差在0.01 km以内,能以单侧信息定位单相接地故障点,即使线路分支数增加也不会带来测量与计算工作量的增加,且特征量的波形可以由微机保护以及变电站综合自动化装置记录,因此对于配电网十分实用。     

供配电系统中性点运行方式与接地

主要介绍供配电系统常见的安装与接线错误及人为故障处理方法,中性点的接地方式、系统类型,跨步电压和接触电压,以及正确的安装方法.     

基于单侧信息的多分支配网单相接地故障定位EI北大核心CSCD

单相接地故障是配电网中最常见的故障类型,但查找发生在带分支配电线路中的单相接地故障点比较困难。针对该问题,通过在线路最长分支末端健全相设置人为接地点,将单相接地故障转化为两相接地故障,在人为接地相回路电压方程的基础上推导了故障区段预判算法,在故障相回路电压方程的基础上推导了故障测距算法,并提出了故障区段预判结果检验和校正算法。理论推导和MATLAB/Simulink仿真实验证明了上述算法最终定位误差在0.01 km以内,能以单侧信息定位单相接地故障点,即使线路分支数增加也不会带来测量与计算工作量的增加,且特征量的波形可以由微机保护以及变电站综合自动化装置记录,因此对于配电网十分实用。     

IGBT超音频电源保护系统研究

在IGBT超音频感应加热电源实际应用过程中,因各种人为原因或客观因素,常常造成电源发生故障并损坏。本文对IGBT超音频感应加热电源易产生的常见故障、关键故障以及产生故障的原因进行了分析,并设计了相应的保护措施和保护电路,使其在发生故障时能及时保护电源设备。该保护电路和保护措施的有效性已在实践中得到验证。     

传真机常见故障判断和检修实例

传真机在我国已得到普及并进入实用阶段,它给人们带来了许多方便,且操作也较简单。但出现故障后的排除是每位关心它的人要迅速解决的问题。笔者以教学和实践方面的经验,向读者讲述判断故障的方法和传真机经常出现的故障,并以UF—2EXC为例举几个检修实例。传真机故障分为:人为故障和自然故障。人为故障一般是指初涉传真机用户使用不当,不认真看使用说明书(当然有很多进口传真机不易看懂外文),笔者曾维修一台松下传真机,这台传真机在使用时发现不     

排除微机假故障

平时常见的微机故障现象中,有很多并不是真正的硬件故障,而是由于人为的疏忽或系统特性不为人知而造成的假故障现象。因此认识下面的微机假故障现象有助于迅速确认故障原因。     

核电站人因失误的产生机理及其预防措施

在核电站的人-机系统中，核电站特有的运行控制特征使得人因失误事件的发生概率很大，如何预防与减少人因失误，提高人的可靠性已成为保证核电安全生产的主要因素。研究了人因失误的特点，通过总结核电站人因失误事件的产生机理，给出了预防核电站人因失误的有效措施。     

静电放电对无绳电话充电接触失效的影响

进行高压静电条件下的加速失效模拟实验,测量无绳电话充电接触失效循环寿命,证实人体静电放电对充电电极寿命的影响。通过扫描电子显微镜观察触头显微形态和进行表面元素成分的半定量分析,从理论上研究充电接触失效的微观过程和作用机理。研究结论对合理选择电极材料、进行表面处理和防护以及改进电极组件设计具有参考意义。     

高频小功率硅双极晶体管不同管脚端对静电放电失效的机理

在人体模型静电放电（electrostatic discharge,ESD）的注入作用下,部分高频小功率硅双极晶体管对人体模型静电放电最敏感的管脚端对不再是普遍认为的发射极E-基极B间的EB反偏结,而是集电极C与基极B间的CB反偏结。为此,采用微观失效分析与计算机模拟仿真分析相结合的方法,详细讨论了不同管脚对引发典型高频小功率硅双极晶体管ESD失效的效应机理,并针对典型器件内部不同位置的损伤点逐个进行分析。最终得出：高频小功率硅双极晶体管的明显失效往往是由于热二次击穿造成的基极有源区与发射极之间的熔融穿通引起的,而ESD潜在性失效发生的主要原因则是其基极或发射极金属电极附近绝缘介质的场致击穿,从而影响高频小功率硅双极晶体管使用的可靠性。     

Towards a Conceptual Framework for Resilience Engineering

As systems continue to grow in size and complexity, they pose increasingly greater safety and risk management challenges. Today when complex systems fail and mishaps occur, there is an initial tendency to attribute the failure to human error. Yet research has repeatedly shown that more often than not it is not human error but organizational factors that set up adverse conditions that increase the likelihood of system failure. Resilience engineering is concerned with building systems that are able to circumvent accidents through anticipation, survive disruptions through recovery, and grow through adaptation. This paper defines resilience from different perspectives, provides a conceptual framework for understanding and analyzing disruptions, and presents principles and heuristics based on lessons learned that can be employed to build resilient systems.      

Programmable Electronic and Hardwired Emergency Shutdown Systems: A Quantified Safety Analysis

Emergency shutdown systems (ESDs) for mining machinery provide critical functions to safeguard miners. Traditionally, ESDs were realized with simple hardwired circuits; today, there is a growing trend to use programmable electronic technology such as programmable logic controllers (PLCs). This paper describes an analytical study to quantify the safety integrity of a PLC-based ESD and a hardwired ESD. The safety integrity level (SIL) of each design approach was determined by quantifying the average probability of failure on demand (PFD_avg) described by the recommendations for programmable electronic mining systems published by the National Institute for Occupational Safety and Health and the IEC 61508 international standard. The safety analyses addressed system architecture, hardware failure probability, proof test interval, diagnostic coverage, and human error probability. The results indicated that a same level of safety, SIL 3, could be attained when evaluating random hardware failures. Neither approach could attain SIL 3 if manual activation was used. Human error was the limiting factor where, using human reliability analysis,PFD_avg < 1x 10 ^-1; thus, the ESD does not meet SIL 1. It is apparent that automatic verses human-activation of the ESD is a very important safety consideration. Manually actuated ESDs can only achieve SIL 1 regardless of the technology; therefore, additional independent safety layers of protection are needed to exceed SIL 1. Second, it is apparent that the technology choice is very important. The PLC-based ESD was much simpler to design and to validate safety.     

Absolute vs. comparative end-of-life age

Conventional insulation statistics typically use test averages of a normal, log normal, or Weibull distribution to compare the quality of different materials or constructions. None of these numbers characterizes an age at end of life with a near 100% reliability, which is necessary to predict when failure occurs. This is a major fundamental and misleading aspect in the manner in which life and age data is reported. The distributed nature of insulation aging and failure requires taking into account the length of samples to report age at end of life. This implies that probability of failure at any time should be reported as a function of cable length. Simply reporting an average probability of failure can endanger human life and have negative economic consequences. This paper shows test data and a method of calculating end of life that provides high reliability operation of aircraft wire that is aging from root-cause stresses. The authors believe this paper treats a major refinement which is essential for realistic prediction of insulation end of life, for instance in the control of reliable operation of aircraft electrical wiring. This technique is now being used in maintenance scheduling of active aircraft and is hoped to influence future revisions of standards     

31P-NMR spectroscopy of human blood and serum: first results from volunteers and patients with congestive heart failure,diabetes mellitus and hyperlipidaemia

³¹P-containing metabolites in human blood, serum and erythrocytes were measured or calculated. Phosphodiesters were found in serum, but not in erythrocytes. 2,3-diphosphoglycerate and 2,3-diphosphoglycerate/ATP ratios were increased in patients with congestive heart failure (2,3-diphosphoglycerate by 13% in mild to moderate, 31% in severe congestive heart failure, 2,3-diphosphoglycerate/ATP ratio by 9% in mild to moderate, 38% in severe congestive heart failure); phosphodiesters were increased in diabetes mellitus (by 26%) and even more so in hyperlipidaemia (by 57%). Changes of blood³¹P compounds with disease states may have diagnostic potential and should be recognized for correction of organ spectra.     

Horns Rev海上风电场探析

海上风电场是风电行业的一个发展方向,介绍了世界首座大型海上风电场Horns Rev的基本建设状况、环境影响、运行故障及经验总结等多个方面.具体聚焦了Horns Rev的风机、电缆、变电站等基础建设内容,物理环境、生物环境、人类活动等环境影响情况、以及运行故障、补救方式、经验教训等情况.     

继电保护装置的多因素时变Markov模型及其检修策略分析

高可靠性微机继电保护装置的人为失效、软件失效以及不同检修模式等因素造成的失效不可忽略。同时,其失效率在全寿命周期内并非恒定。针对上述问题,分别建立了考虑多重因素的单个保护装置5状态Markov模型和双重化保护的14状态Markov模型。考虑时变失效因素与检修因素,并对部分检修与全部检修进行区分,比较相应的时变不可用率变化,并给出最优检修策略。     

An adaptive fuzzy self-learning technique for prediction of abnormal operation of electrical systems

This paper introduces the details of an intelligent adaptive fuzzy system-with self-learning functions-that could be installed to monitor electrical equipment or systems, and self-learn the trend of events leading to the failure of the monitored system. If any of the learned trends is repeated, the intelligent fuzzy system will predict the eventual failure of the monitored system in case of either human or automatic nonintervention. This paper presents the design details of the new intelligent fuzzy predictor. The self-learning process is accomplished using adaptive neuro-fuzzy techniques. Full details of the development of the new tool and the results of several test cases based on various practical applications and real-site data are included. Wavelet denoising is also used as the filtering technique for pre-preparation of the data before introducing it to the fuzzy predictor.