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从防雷工程设计施工实践出发,按照国内外相关防雷技术标准中的规定,对TN和TT系统这两种主要接地制式的低压配电系统中不同SPD接线方式进行了分析。结果表明,TT制低压配电系统适宜采用“3 1”保护模式的SPD接线方式;对于有剩余电流保护器(RCD)的TT制低压配电系统,“4 0”保护模式的SPD只能安装在RCD负荷侧或采用“3 1”保护模式的SPD;对于SPD的接地独立于配电系统接地的TN制低压配电系统,其SPD的安装应将TN系统视为TT系统。 相似文献
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正确识别低压供配电系统和类型,并检测接地是否符合设计要求是防雷工程检测必不可少的内容之一。低压供电系统的接地制式是按照配电系统和电气设备不同的接地组合来分类。文章对低压配电系统接地制式的分类和表示法、接地制式的特点、接地制式的选用等进行详细的叙述,并指出了检测内容、方法及合格标准,供防雷技术人员学习和应用。 相似文献
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针对现行民用建筑电源SPD的检测方法缺失所造成雷害风险问题,从电源进线方式和电源供电制式开始考虑,根据电源SPD产品设计参数来确定所用产品是否与被保护的线路设备相适应。再根据电源SPD的震荡保护距离、感应保护距离和SPD有效电压保护水平来决定被保护的线路设备是否处于SPD的保护距离内。最后再对电源SPD的安装工艺和接地电阻等具体数值进行检测,以综合系统的分析来确保电源SPD的检测质量,保障居民线路设备的安全。 相似文献
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通过电涌保护器(SPD)在某住宅小区经受雷击考验的案例,依据<建筑物防雷设计规范>要求,总结了住宅小区浪涌保护器的设置依据与方法.对于独立低压电源埋地电缆进入住宅楼的配电方式,只需在住宅楼房总配电箱安装一级SPD,不必要在每个单元或总电源处低压侧再安装SPD;对于架空低压线路配电方式,需要加大选定SPD的标称放电电流或冲击通流容量即可.从住宅人身安全考虑,住宅楼还应设置等电位接地端子,特别是洗浴卫生间必须设置局部等电位接地端子. 相似文献
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张士海 《沙漠与绿洲气象(新疆气象)》2009,3(Z1)
对电源防雷器(SPD)的类型以及设备的使用情况和电源的制式、电源的线径与电源防雷保护器安装的距离和接地方面进行阐述,只有正确地选择、配置、安装才能使SPD达到预期的效果. 相似文献
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电子信息网络系统配电的重复接地问题 总被引:1,自引:0,他引:1
目前我国的低压供配电方式多采用TN接地形式,而国标要求电子信息网络系统应采用TN-S或TN-C-S制式,因此电子信息网络系统的配电方式需要进行改造。在低压供电线路中增加一接地端子与PEN短接,即为重复接地,转换成三相五线制供电。 相似文献
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Chinese Contribution to CMIP5:An Overview of Five Chinese Models’Performances 总被引:4,自引:0,他引:4 下载免费PDF全文
ZHOU Tianjun CHEN Xiaolong DONG Lu WU Bo MAN Wenmin ZHANG Lixi LIN Renping YAO Junchen SONG Fengfei ZHAO Chongbo 《Acta Meteorologica Sinica》2014,28(4):481-509
An overview of Chinese contribution to Coupled Model Intercomparison Project-Phase 5 (CMIP5) is presented. The performances of five Chinese Climate/Earth System Models that participated in the CMIP5 pro ject are assessed in the context of climate mean states, seasonal cycle, intraseasonal oscillation, interan-nual variability, interdecadal variability, global monsoon, Asian-Australian monsoon, 20th-century historical climate simulation, climate change pro jection, and climate sensitivity. Both the strengths and weaknesses of the models are evaluated. The models generally show reasonable performances in simulating sea surface tem-perature (SST) mean state, seasonal cycle, spatial patterns of Madden-Julian oscillation (MJO) amplitude and tropical cyclone Genesis Potential Index (GPI), global monsoon precipitation pattern, El Ni-no-Southern Oscillation (ENSO), and Pacific Decadal Oscillation (PDO) related SST anomalies. However, the perfor-mances of the models in simulating the time periods, amplitude, and phase locking of ENSO, PDO time periods, GPI magnitude, MJO propagation, magnitude of SST seasonal cycle, northwestern Pacific mon-soon and North American monsoon domains, as well as the skill of large-scale Asian monsoon precipitation need to be improved. The model performances in simulating the time evolution and spatial pattern of the 20th-century global warming and the future change under representative concentration pathways pro jection are compared to the multimodel ensemble of CMIP5 models. The model discrepancies in terms of climate sensitivity are also discussed. 相似文献
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Land retrievals using passive microwave radiometers are sensitive to small fluctuations in land brightness temperatures. As such, the radio-frequency interference (RFI) signals emanating from man-made microwave radiation transmitters can result in large errors in land retrievals. RFI in C-and X-band channels can con-taminate remotely sensed measurements, as experienced with the Advanced Microwave Scanning Radiometer (AMSR-E) and the WindSat sensor. In this work, applications of an RFI detection and correction algorithm in retrieving a comprehensive suite of geophysical parameters from AMSR-E measurements using the one-dimensional variational retrieval (1-DVAR) method are described. The results indicate that the values of retrieved parameters, such as land skin temperature (LST), over these areas contaminated by RFI are much higher than those from the global data assimilation system (GDAS) products. The results also indicate that the differences between new retrievals and GDAS products are decreased evidently through taking into account the RFI correction algorithm. In addition, the convergence metric (χ2) of 1-DVAR is found to be a new method for identifying regions where land retrievals are affected by RFI. For example, in those regions with much stronger RFI, such as Europe and Japan, χ2 of 1-DVAR is so large that convergence cannot be reached and retrieval results may not be reliable or cannot be obtained. Furthermore,χ2 also decreases with the RFI-corrected algorithm for those regions with moderate or weak RFI. The results of RFI detected byχ2 are almost consistent with those identified by the spectral difference method. 相似文献
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车载应急气象台防雷设计 总被引:1,自引:0,他引:1
车载应急服务移动气象台主要用于突发性事件、重大气象灾害、重大社会活动等应急气象保障工作,使抢险救灾和重大社会活动现场气象服务更直接、更及时、更有效。体现了气象工作在不同环境和恶劣自然条件下开展气象观测、探测、天气预报预测,提供准确的气象预报服务能力。 相似文献
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SMS在新一代天气雷达运行状态监视报警中的应用 总被引:3,自引:2,他引:1
引言
新一代天气雷达具有观测时空分辨率高、连续工作等一系列特点,决定了它在现代气象观测业务中的重要地位。由于新一代天气雷达观测时间密度大,处于24h工作状态,不可避免会出现故障,依靠人工对其运行状态进行完全监视不可能实现,很多突如其来的故障不是马上就会引起雷达值班人员的注意,所以有必要建立新一代天气雷达运行状态监视和报警系统。 相似文献
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陈学溶 《南京气象学院学报》2014,(2):243-244
1935年,国立中央研究院第一届“聘任评议员”蒋丙然老前辈的落选,曾引起了蒋氏父子以及某些不明真相人士的愤慨。半个世纪以后1985年11月25日蒋老的哲嗣蒋君宏先生曾在台湾写了一封7页的长信,内中有一段回忆了此事的经过,现照录于下: 相似文献
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陈学溶 《南京气象学院学报》2013,(5):635-636
航空天气报告和航空天气预报是飞行正常和安全的重要保证。在民航重大飞行事故中,天气因素所占的比重相当大。上海龙华机场中航(中国航空公司的简称,下同)气象台自从抗日战争胜利后重建之日起到1949年暮春中航总公司撤离上海时为止的大约三年半中,由于航空天气预报失误而致中航飞机失事的情况还没有出现过。但是,因为驾驶员处理失当致航机在执行任务时,由于天气原因而遭致重大事故,却有多起。 相似文献
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During August 2013, a mobile Rayleigh lidar was deployed in Lhasa, Tibet (29.6°N, 91.0°E) for mak- ing measurements of middle atmosphere densities and temperatures from 30 to 90 km. In this paper, the authors present the initial results from this scientific campaign, Middle Atmosphere Remote Mobile Observatory in Tibet (MARMOT), and compared the results to the MSIS-00 (Mass Spectrometer and Incoherent Scatter) model. This work will advance our understanding of middle atmos- phere dynamic processes, especially over the Tibetan Pla- teau area. 相似文献
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Variation Trend and Characteristics of Anthropogenic CO Column Content in the Atmosphere over Beijing and Moscow 下载免费PDF全文
WANG Pu-Cai Georgy S.GOLITSYN WANG Geng-Chen Evgeny I.GRECHKO Vadim S.RAKITIN Ekaterina V.FOKEEVA Anatoly V.DZHOLA 《大气和海洋科学快报》2014,(3):243-247
The anthropogenic CO column content in the atmosphere is derived from measurements with infrared grating spectrometers in Beijing, China, and Moscow, Russia, during 1992-2012. Some specific variation char- acteristics and long-term variation trends of the CO col- umn content in the atmosphere in these regions are dis- cussed. An evident variation trend of anthropogenic CO in the atmosphere for the Beijing region is not observed during 1992-2012, while for the Moscow region, it de- creases yearly by about 1.4% for the same period. High CO concentrations appear quite frequently in Beijing, but much less frequently in Moscow, except during the natu- ral fire events in summer 2010. From back trajectory analysis, the high CO concentration observed in Beijing can be attributed to the intensive CO emission sources in its surrounding areas. 相似文献
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Stratospheric aerosol extinction profiles are retrieved from Scanning Imaging Absorption Spectrome- ter for Atmospheric Cartography (SCIAMACHY) limb scatter measurements. In the process of retrieval, the SCIATRAN radiative transfer model is used to simulate the limb scattering radiation received by the SCIAMACHY instrument, and an optimal estimation algorithm is used to calculate the aerosol extinction profiles. Sensitivity analy- ses are performed to investigate the impact of the surface albedo on the accuracy of the retrieved aerosol extinction profiles in the northern midlatitudes. It is found that the errors resulting from the bias of the assumed surface albedo in the retrieval are generally below 6%. The retrieved SCIAMACHY aerosol extinction profiles are compared with corresponding Stratospheric Aerosol and Gas Experi- ment (SAGE) II measurements, and the results indicate that for the zonal mean profiles, the SCIAMACHY retrievals show good agreement with SAGE II measurements, with the absolute differences being less than 2.3 × 10-5 km-1 from 14-25 km, and less than 5.9×10-6 km-1 from 25-35 km; and the relative differences being within 20% over the lati- tude range of 14-35 km. 相似文献
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陈学溶 《南京气象学院学报》2013,(5):639-640
蒋丙然老前辈是中国近代气象事业的先行者,也是主要奠基人之一。他在75岁高龄时(1957年)撰写的《四十五年来我参加之中国观象事业》一文(以下简称“蒋文”),可以认为是一篇高度概括了他一生科学事业(主要是气象事业)的自传。它是欲知中国早期近代气象事业发展过程的人,不可不熟习的重要文献。但似有某些不足之处。 相似文献