正泰NRT36-00熔断器

<正>产品用途及使用范围浙江正泰电器股份有限公司生产的NRT36-00熔断器适用于交流45～62Hz、额定电压690V、额定电流2～160A,主要用于电气线路中短路或过载保护。熔断器具有耐受预期短路冲击电流100kA的能力。额定分断能力为AC500V120kA,AC690V50kA。使用类别为gG。符合GB/T13539.2—2002,GB/T13539.6—2002及相应的IEC60269标准。随着电力系统不断升级改造,对熔断器提出了高分断、小体积、大容量、多功能、个性化等要求。     

高速铁路GSM-R无线传播特性分析

<正>1概述高速铁路GSM-R系统无线场强覆盖的完整性和信号冗余度要求较一般公众移动通信网络高得多,而且高速铁路地形地貌具有特殊性,无线覆盖场强预测成为高速铁路GSM-R网络规划中的重点和难点,场强预测依赖于对电     

Zero Waste and Conversion Efficiencies of Various Technologies for Disposal of Municipal Solid Waste

Zero waste is a philosophy and a design principle of dealing with our waste stream for the 21st century. After reviewing the available information, the goal of zero waste from landfill is considered to be unachievable by using known and proven methods and approaches. The comparison of various technologies shows that the conversion efficiencies depend upon the type of system chosen for processing residual waste, and the best overall diversion rate of waste management system that can be achieved is about 71%. The maximum achievable overall diversion rate can be increased to approximate 92% if current environmental regulations to permit the routine use of the bottom ash or char for advanced thermal technologies.     

Real-Time Method for Detecting Harmonic and Reactive Currents of Single-Phase Circuits

According to the characteristics of single-phase circuits and demand of using active filter for real-time detecting harmonic and reactive currents, a detecting method based on Fryze＇s power definition is proposed. The results of theoretical analysis and simula- tion show that the proposed method is effective in realtime detecting of instantaneous harmonic and reactive currents in single-phase circuits. When only detecting the total reactive currents, this method does not need a phase-locked loop circuit, and it also can be used in some special applications to provide different compensations on the ground of different requirements of electric network. Compared with the other methods based on the theory of instantaneous reactive power, this method is simple and easy to realize.     

论间歇式沥青混凝土拌和设备的操作方法和技巧

保证沥青混合料的质量是保证高速公路成品路面质量的重要因素之一,而沥青混合料的拌和生产工艺是保证混合料质量的重要环节,沥青混凝土拌和设备的操作在其中起着举足轻重的作用.本文围绕保证沥青混凝土成品料质量这一宗旨,以NP-3000CA间歇式沥青混凝土拌和设备为实例,对间歇式沥青混凝土设备的的正确操作和一些技巧进行了介绍.     

微电机新型过热过电流自保结构中的高分子PTC元件

研制了一种高分子PTC元件，并利用这种高分子PTC元件设计制作出了微电机的新型自保结构。     

三相异步电动机工作绕组温升的单片机检测

三相异步电动机工作时，电动机各相工作绕组中流过电流，电流的热效应使工作绕组发热，对应于电动机工作前工作绕组的温度，电动机工作一段时间后，各相工作绕组的温度升高．要使电动机正常工作，其工作绕组温升应在一定范围之内，若工作绕组的温升过高，就会影响到电动机的正常工作．因此，电动机工作绕组的温升是电动机出厂前检验的一项重要参数．一般的方法是用惠斯通电桥或者开尔文双臂电桥检测出三相电动机工作前工作绕组的冷态电阻和电动机工作一段时间后的热态电阻，然后换算出工作绕组温升．既不方便测量，精度也不高．     

THE EDDY LOSSES OF A MAGNETIC THRUST BEARING

Accurate calculations of losses associated with the operation of magnetic bearings are particularly important for high speed applications where the rotor losses are expected to be large and for some particular applications where even low power losses will be critical. Power losses in the magnetic thrust bearing is often neglected, but if there is misaligned in the rotor and bearing, the magnetic field in the thrust bearing is no longer axisymmetric one, or the dynamic control current in the winding is time dependent one, eddy currents are caused to flow inside the conducting material, then the power losses are very important for magnetic bearing design. This paper presents an analytical model of a thrust magnetic bearing, and the magnetic fields, forces and losses of thrust magnetic bearing are calculated. In the calculations the frequency of dynamic control current is up to 1 000 Hz, rotating speed is from 60 rpm to 1 200 rpm, and the non-linearity of material is also taken into consideration. The results shows that if the magnetic field is not saturation, the eddy losses is proportional to dynamic control current frequency and a square function of dynamic control current, and also 5/2 power function of shafts speed.     

公安交通指挥系统防雷接地保护措施

公安交通指挥系统融合了先进的传感技术、信息技术、通信技术、计算机技术和系统工程等技术的设备，这些先进设备基本上是以耐压能力较低的电子设备为主。设备使用时务必要有安全的防雷接地保护措施，因为雷击电流对设备的破坏不仅造成设备自身的损坏，而且由此引起的间接损失也很大。从雷电的方式看，主要有三种，即“直击雷”、“感应雷”和“传导雷”。综合公安交通指挥系统的设备使用特点，笔提出了设备外场综合防雷和内场综合避雷供业内人士参考。