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隔离开关是电力系统中不可少的电气元件。它在运行中常发生的缺陷是导电回路过热。一旦隔离开关发生过热故障,则需限制负荷,有时必须紧急停电进行处理,严重影响电力系统的安全运行及供电可靠性。因此,应重视隔离开关的过热。笔者提出了相应的预防措施,供同仁参考。 电力系统中使用的隔离开关的导电回路,主要由动、静触头构成的主刀口接触导电片(杆)、导电片(杆)与接线座的过渡接触、引线接线座等组成。因此过热的部位主要是主接触刀口、过渡接触、引出线接线座。隔离开关发热的主要原因是,动、静触头刀口接触不良,动、静触头接触压力不足,动、静触头机械变形或机械磨损,动、静触头的电磨损,动、静触头接触面上存有脏污物、化学尘垢及氧化层,使接触面电阻增大。导电片(杆)与接线座间过热。隔离开关的导电 相似文献
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隔离开关在电力系统中,起着隔离电源、接通和断开小电流的作用,要求在运行中受到短路电流热效应与电动力的作用时应有足够的稳定性。隔离开关运行中动、静触头接触部分发热是它的常见故障,一般是动、静触头之间由于弹簧压力小、操作时触头未完全合到位、触头氧化接触不良等造成接触部分发热。下面对一起因人为因素,造成隔离开关动触头座靠支持绝缘子处严重发热故障进行分析,并提出预防对策。1故障现象某局一台GN8—10型隔离开关因操作损坏后,更换同型号的隔离开关(额定电压10kV、额定电流400A)后投入运行。此时负荷为2000kW,电流245A、电… 相似文献
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分析了一起220 kV GIS隔离开关合闸不到位故障案例.利用X光拍摄技术,精确测量该220 kV GIS隔离开关动触头伸出屏蔽罩的长度,通过对比其他正常分闸的隔离开关动触头状态,确认动触头伸出屏蔽罩长度超过厂家设计值上限;通过对该220 kV GIS隔离开关操作机构的全面检查,进一步发现齿轮箱内部有进水受潮迹象,确定... 相似文献
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某110kV变电站为老式变电站,因设备老化,需要对该变电站的110kV隔离开关进行改造,将原有手动操动机构更换为电动操动机构。由于改造前使用手动操动机构,故该变电站的隔离开关操作一直依靠微机"五防"系统来实现防误操作功能。 相似文献
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变电站是电能传输过程中的重要环节,站内隔离开关的检修会造成变电站停电,从而直接影响变电站辐射区域内的生产和生活,因此减少隔离开关检修时间将会直接减少变电站辐射区域内的经济损失。通过总结现场更换静触头作业过程,从而研制出新的静触头吊装工具,提升工作效率,减少区域内经济损失。 相似文献
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《Journal of Agricultural Engineering Research》1998,69(3):249-254
A model to represent the discolouration of dried powder of carrots as a function of temperature was developed. Two types of carrots, Asian and European, containing large amount of lycopene and β-carotene, respectively, were tested. The dried powder was stored under an atmosphere with O2and at three different temperatures, 5,20 and 35°C. The surface colour of the powder was monitored during storage by a Hunter colour ratioa/b. In the proposed model, the rate of oxidation was assumed to be represented by the product of the fraction of concentration of oxidized pigment at arbitrary time and a specific rate of oxidation of pigment. The rate parameters in the proposed model were calculated by fitting the experimental data with smooth curves by trial and error at the end of the induction period but before discolouration took place. The frequency constant and activation energy, expressing the temperature dependence of the rate parameters, were expressed by the Arrhenius relation. The simulation results of a Hunter colour ratioa/bof dried powder at 25°C showed good agreement with the experimental data, suggesting that the proposed model was effective for the prediction of discolouration of dried powder of both types of carrot. The use of the induction period in the manner described may enable the shelf life of dried powder to be predicted. 相似文献
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感官检验棉花的品级,这是农村常见的一种检测手段.它的一个主要特点就是存在不确定性.这是由于检验员的品级检验水平存在一定的差异,其中有很多因素制约着检验的结果.文章对影响感官检验结果的因素进行了系统的分析. 相似文献
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从灾害经济学的角度探讨了城镇供水优化调度的必要性和可能性,认为在缺水不可避免的情况下,对供水进行优化调度可以减小缺水带来的损失,产生较好的减灾效益,特别是可以大大减小严重干旱的灾害效应。并根据水资源的特性,提出了缺水损失的计算模式以及优化调度的原则和方法。 相似文献
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The fractional outflow rate of water from the rumen, measured as the rate of disappearance of the chromium complex of ethylenediamine tetra-acetic acid, was related to a number of dietary factors. A multiple regression equation was derived which expressed fractional outflow rate as a function of the intakes of dry matter, ash, acid-detergent fibre and crude protein.The data analysed consisted of 243 observations for sheep on 59 diets, including forage, concentrate and mixed diets. The ranges covered by the data were: fractional outflow rate 0.7–3.6 day?1; dry matter intake 560–1400g/day; ash 4–30%, acid-detergent fibre 7–41%, crude protein 5–26 % of dry matter; there were no observations for sheep of less than 34 kg liveweight.The equation accounted for 56·3 % of the total variance. Between-sheep variance could not be calculated for the whole of the data but was undoubtedly substantial since, for a sixth of the data, it was known to account for 38 % of the total variance. 相似文献