东风4B型机车起动发电机故障时的应急处理方法

我段运用的东风4B型机车近一段时间连续发生起动发电机绝缘值低或绕组开路等故障。所幸这类故障都在段内检修中发现并及时得到处理,避免了故障扩大。但是,此类故障如发生在运行途中并造成起动发电机不能继续工作时该如何处理呢? 我们知道,机车在运行途中起动发电机如果发生故障,不能做为发电机继续使用时,机车控制回路将由蓄电池提供工作电源,并且空压机电机、动力室左右通风机和司机室电炉子由于逆流装置的不可逆原理将不能使用。此时机车如果继续运行,将面临如下几点隐患：第一,机车不能回手柄停机,因为停机后,由于起动发电机不动作,机车将不能重新起机,可能造成耽误正线时间过长,形成机破。第二,如果空压机电机不动作,机车将不能打风,机车空气制动不能使用,列车进站或进入限速区间时将不能施行空气制动。第三,由于起动发电机不再向蓄电池充电。蓄电池会严重亏电,机车不能继续工作。     

电力线路故障的排除方法

在电力线路及设备中,电路经常会出现故障.当电路发生故障时,设备将无法正常工作.那么,当电力线路发生故障时,我们应该根据具体故障的特点,查找故障,并排除.     

轴瓦拉床电气线路的改进

1 问题的提出 轴瓦拉床是加工内燃机轴瓦的专用机床,用以拉削半圆轴瓦的对接平面。我厂为加工需要使用了多台拉床,其机械传动采用液压伺服系统,电气系统采用接触器—继电器控制,控制对象为液压油泵电机和液压电磁阀。 加工时如图4所示,将待加工产品放入座模,先用托架将产品两加工面托平,然后用压头顶紧,再放下托架。最后,安装在拖板上的拉刀水平向前运动,对两个加工面进行拉削,如图2所示。其电气线路图如图3所示（主电路省略）。1c控制液压泵电机,7c控制润滑、冷却泵电机,Z CT1～5为直流液压电磁阀。手柄①有三个位置,采用机械定位自锁,手柄②无定位,搬动后马上复位。在工作起点4xwk被压迫,5xwk复位,在行程终点5xwk被压迫,4xwk复位。     

X195型柴油机冷起动性能的试验研究

在涡流室式柴油机中由于流动损失和散热损失较大,起动困难,一般在涡流室镶块上加工一个伞形小孔辅助起动;对起动小孔辅助柴油机起动的机理多年来可归纳成以下两种认识:一种是认为起动小孔的作用是当柴油机起动时使一部份燃油通过起动小孔直接喷到主燃烧室内辅助起动,如图1所示;另一种认为当柴油机起动时由于涡流室内涡流强度弱,油束被吹偏程度小,油气混合不良,而由起动小孔喷射出一股气流对准油束,加强油气的接触混合,以利于燃油着火起动。如图2所示。针对以上两种论述,作者在X195柴油机上设计了两种涡流室镶块方案并进行了试验。方     

一种水位自动控制的实用电路

水位自动控制装置的种类很多 ,过去常用的浮球式、干簧管式水位控制装置 ,现在多被电子装置所替代。笔者根据多年实践经验 ,设计、制作一种简单实用水位自动控制的电路 ,用于本公司各个水塔的水位控制效果较好 ,特别是节水明显 ,因而节约大量能源。现介绍如下以供参考。图 1　水位自动控制装置电路总图　　如图 1所示就是一种水位自动控制的实用电路用于水塔的总图。工作原理简述如下 ,在水塔中设置三根不同长度的水位电极ＥＡ、ＥＢＥＣ,当三相开头ＤＫ1、单相开关ＤＫ2 和控制电路开关Ｋ2 合上后 ,装置开始工作。如果这时水位低于ｂ位置线…     

东风4型机车主电路图线号记忆法

东风型机车是我国铁路运输生产的主型机车,在使用中经常出现这样那样的故障,特别是电气方面故障较多.这就要求乘务人员、检修人员、专业人员对线路线号熟悉,及时判断、查找、处理故障,保证机车正常运行.本人对主电路线号记法按主要部件、自然序号摸出一点规律仅供参考.     

变频调速问答(二)变频器的主电路

变频器的内部主电路 　　问题1变频器的内部主电路是怎样构成的? 　　1)基本结构低压中、小容量的变频器都采用“交-直-交“变换方式,基本电路由整流和逆变两大部分组成,如图1所示. 　　……     

太阳能发电系统的DC／DC电路单元

描述了太阳能发电系统ＤＣ／ＤＣ电路单元主回路的线路结构,并简述了驱动电路的控制原理。     

摩托车蓄电池故障的排除实例分析

1　故障现象一辆某品牌 100型三轮摩托车,蓄电池亏电,维修人员进行了检查,更换了蓄电池,故障仍未能排除。2　故障分析与排除开启点火开关,按下起动电钮进行发动机起动检验,起动电机投入工作,但工作无力,只拖动发动机缓慢地转了几圈,就不再动了。检验结果说明蓄电池严重亏电。对     

电接点压力表用于空压机的自控

<正> 读1985年第九期《节能》上的“电接点压力表用于空压机的节电改造”一文,我觉得有待改进:1.假设电接点压力表损坏或控制系统出故障,而未排除以前,该图便不能运行;2.线路越复杂,出故障的机会越多。该图可以减少一个中间继电器,这对使用、维修都会     

新风量、送风方式和空调病症

本文叙述了新风量的大小和送风方式的不同与空调病症之间的关系。     

The effects of air leaks on solar air collector behaviour

The construction of conventinal solar air collectors and the fact that they will operate with a significant pressure difference between the heated air stream and ambient, suggests that significant quantities of air may leak into or out of them. A search of the literature reveals no consideration of the effects these air leaks may have on the validity of collector efficiency measurements, on the efficiency itself, or indeed what the meaning of efficiency is under such operating conditions. This paper discusses the meaning of collector efficiency when leaks into the collector occur, analyses the effects on efficiency measurements, and solves the collector efficiency for the simple case of a constant leakage rate along the collector. Assuming that air leaking in from ambient can replace deliberate fresh air supply to the load as in building heating, then significant measurement errors are made if air leaks in to the collector are not accounted for. Further, the collector efficiency is increased over the no leak case, so that complex construction methods to make the collector air tight are probably not warranted.     

降低进口温度与湿度增加空压机风量的理论与实践

本文阐述了空压机增风改造的方法,并介绍了脱湿增风改造原理及其实践效果,在新余钢铁公司气体厂1TY-575/5.5-Ⅲ型空压机增风改造中应用,使空压机夏季平均风量可提高8%左右,而且空气压缩的单位电耗降低.     

Effect of air leak on long term performance of air heater

In this paper, the effect of an air leak on the air heater performance is investigated. “Air leaking in” and “air leaking out” systems are examined. The effect of various parameters like leakage rate, mass flow rate, solar insolation, plate length and ambient temperature has been studied. The possibility that air leakage can take place from any where along the length of the collector has been incorporated in the model. It is found that, for “air leaking in” systems, efficiency goes up, while for “air leaking out” systems, efficiency decreases from the no-leak situation, and it depends on the position of the leak.     

空气湿度对平板空气集热器效率的影响

对不同相对湿度下的湿空气密度、定压比热容、动力粘度和导热系数等热物性参数进行了计算。在给定的平板空气集热器模型下计算得出,工作介质为相对湿度50%的湿空气比工作介质为干空气的集热器效率高12.4%。文章研究分析了太阳辐射量、空气通道高度、入口空气流速及温度对平板空气集热器顶部损失系数和效率的影响,研究结果显示,它们对介质为干空气及介质为湿空气的集热器影响趋势一致。     

Highly durable and active non-precious air cathode catalyst for zinc air battery

The electrochemical stability of non-precious FeCo-EDA and commercial Pt/C cathode catalysts for zinc air battery have been compared using accelerated degradation test (ADT) in alkaline condition. Outstanding oxygen reduction reaction (ORR) stability of the FeCo-EDA catalyst was observed compared with the commercial Pt/C catalyst. The FeCo-EDA catalyst retained 80% of the initial mass activity for ORR whereas the commercial Pt/C catalyst retained only 32% of the initial mass activity after ADT. Additionally, the FeCo-EDA catalyst exhibited a nearly three times higher mass activity compared to that of the commercial Pt/C catalyst after ADT. Furthermore, single cell test of the FeCo-EDA and Pt/C catalysts was performed where both catalysts exhibited pseudolinear behaviour in the 12-500 mA cm⁻² range. In addition, 67% higher peak power density was observed from the FeCo-EDA catalyst compared with commercial Pt/C. Based on the half cell and single cell tests the non-precious FeCo-EDA catalyst is a very promising ORR electrocatalyst for zinc air battery.     

空气调节二次回风系统的节能问题

讨论了二次回风系统在夏季工况下与一次回风系统相比的节能效果,以及在冬季工况如何更好降低能耗的问题,着重分析了冬季工况下机器露点对能耗的影响,并提出降低能耗的途径。     

Analysis of exergy demand for air heating of an air handling unit

In modern buildings, an increasing amount of the consumed energy falls on ventilation systems. The amount of energy needed for ventilation depends on weather fluctuations, wind, interaction between natural gravity and air tightness of the building, heat exchangers used in ventilation systems, efficiency of other ventilation equipment, and operating mode of ventilation systems in the building. Ventilation systems are comprised of a variety of elements that facilitate processes using energy of different types. The main elements that use energy in ventilation systems are fans, heat exchangers, and heaters. They have a significant effect on both energy needs of a public building and the exergy efficiency of a system. In order to achieve a more efficient use of exergy in heat exchangers, it is recommended to execute processes under as little temperature difference as possible; however, this increases the area of heat exchangers. Results of the analysis show that it is recommended to design ventilation systems based on the temperature that corresponds with the maximum demand of exergy in order to use the heat recovery unit as much as possible in the system.     

Reversible air electrodes integrated with an anion-exchange membrane for secondary air batteries

Reversible air electrodes integrated with a polymer electrolyte membrane have been proposed for use in rechargeable metal-air batteries or unitized regenerative fuel cells to reduce the impact of atmospheric carbon dioxide. Reversible air electrodes were prepared with an anion-exchange membrane (AEM) as a polymer electrolyte membrane and platinum-based catalysts. The AEM at the interface between the alkaline electrolyte and the air electrode layer plays major roles in AEM-type air electrodes as follows: it blocks (a) the permeation of cations in the alkaline electrolyte into the air electrode layer to prevent carbonate precipitation, (b) penetration of the alkaline solution itself, and (c) neutralization of the alkaline electrolyte by carbon dioxide, all of which prevent performance degradation of oxygen reactions. Catalysts for decreasing the overvoltage of oxygen reactions were also investigated with the AEM-type air electrode, and the overall efficiency was improved due to a remarkable decrease in the potential for the oxygen evolution reaction with Pt-Ir catalysts.