浅谈变电所综合自动化系统的抗电磁干扰

介绍了变电所综合自动化系统电磁干扰的形成、信号模式和传输途径。针对电磁干扰的三要素——干扰源、传播途径和电磁敏感设备，提出了一些抗电磁干扰的措施。     

抗电磁干扰软磁铁氧体技术

简要介绍了电磁干扰的基本概念以及＂黑色陶瓷＂——软磁铁氧体材料在现代抗电磁干扰（EMI）技术中的应用,并论述了软磁铁氧体抗电磁干扰的机理与抑制电磁干扰的方法。     

橡胶加工设备数控系统的抗干扰

对数控橡胶加工设备的干扰问题进行了初步分析和分类。由于干扰存在复杂多变性，所以我们仅结合实际使用情况，提出了一些消除和抑制干扰供参考的方法，特别是对微机控制的橡胶模具加工设备的抗干扰问题作了一些探讨。这对数控橡胶加工设备扩大应用和合理维修，提高经济效益将起到十分重要的作用，应引起人们的足够重视。     

尿素喷头转速示值虚假问题的解决

1　问题分析尿素SI60 1喷头转速探头采用电磁感应原理 ,将探头转速转换成电脉冲传送到控制室进行显示。由于尿素喷头安装在造粒塔顶部 ,信号传送到控制室的信号线距离太长 (大约 1 40m左右 ) ,加之现场环境恶劣 ,各种电磁干扰及电场干扰强烈 ,尽管用了良好的屏蔽电缆也难消除干扰的影响。尿素装置中强电流设备所采用的电源多为工频 5 0Hz ,主要干扰多源于工频干扰。只有消除信号中的工频干扰 ,才能保证辅盘显示仪表及DCS系统指示正确 ,确保有一个准确的示值提供给工艺操作人员进行正确操作。2　技术分析与解决方案图 1为SI60 1系统等效…     

一起感应电压造成的开关量信号干扰案例分析

近几年新建的水泥厂一般采用DCS控制方式,水泥生产设备中高电压、大功率机电设备多,启动瞬间的冲击电流和电压变化幅度激烈,易出现对控制系统的严重干扰。为数众多的直流调速、变频调速和大功率可控硅器件在使用中出现的电网波形畸变和高次谐波是目前公认的破坏性最严重的干扰源。尽管电磁干扰一般出现在模拟量的采集和输出回路中，但设备运行时噪声源对开关量干扰引发的电气故障并不少见，只是开始处理故障时很少与干扰联系起来。以下，笔者介绍一起过去处理过的电磁干扰开关量信号引起的故障。     

粹文详摘

CW29.导电屏蔽塑料 塑料代替金属使电子装置越来越轻量化,但塑料是优良的绝缘体,电磁波可以穿过而无损失,故当塑料用作电子装置的外壳时电磁波可从该装置内发射,干扰附近设备或来自附近其他装置的电磁波干扰该电子装置。这现象称为电磁干扰(EMI)或射频干扰(RFI)。因此要求电子装置既不能对外有电磁干扰又能抵御其它干扰源对它的干扰——把进入和发射的干扰波损耗掉,通常的办法是用金属罩屏蔽,考虑到轻量化要求只能用导电塑料代金属。     

关于电站热控系统干扰分析

本文分析了电厂设备中热控系统常见的电磁干扰,以及对热控系统电磁干扰的机理,分析了干扰影响热控系统正常工作的原因,指出在实际生产中需要考虑控制系统的抗干扰性能,并结合现场实际提出了几种有效的抗干扰措施。     

暂态电磁干扰的电路模型与计算

分析了开关操作暂态对二次电缆的电磁干扰特点、传播途径，着重讨论了开关暂态对二次电缆传导性干扰的电路模型与计算方法。     

涤锦复合超细纤维螺杆挤压机变频调速系统抗干扰改造

阐述了涤锦复合超细纤维螺杆挤压机变频调速系统抗干扰改造的实例,分析了电磁干扰对变频器调速系统的干扰途径及改造措施,解决了螺杆压力控制中干扰的问题,提高了系统的控制精度,满足生产工艺的要求。     

以橡胶铁氧体复合材料为基的微波吸收材料的介电特性

高频微波电子系统的广泛运用产生了某些连带的问题,其中最重要的是电磁干扰。微波装置,例如移动电话,无绳局域网络和自动控制系统可能辐射出有害的电磁信号,对电子装置产生干扰,导致一类特殊的环境污染。在电子设备中采用合适的微波吸收材料可帮助控制电磁波大量的自辐射作用,并保证在存在电磁干扰时设备不受影响。     

综合布线的电磁干扰与抑制

电磁干扰严重影响工业设备或系统自动化生产的安全性、可靠性、适应性和连续性。介绍了电磁干扰源、电磁兼容标准，以及合理布线、接地、电磁屏蔽等一系列抗干扰措施，并提出了系统的电磁干扰发射测量与诊断流程。     

电磁屏蔽涂料的发展现状及趋势

电子产品的日益普及使得电磁干扰成为一个突出问题,应用电磁屏蔽涂料是消除电磁干扰简单而有效的方法,本文介绍了电磁屏蔽涂料的组成、效能评价方法、技术思想、存在的问题以及发展趋势。复合型以及水性屏蔽涂料具有广阔的研发前景,高效能、宽频带、寿命长的电磁屏蔽涂料将会受到市场欢迎。     

数显仪表在生产中的抗干扰措施探讨

着重分析了在生产中使用数显仪表干扰产生的原因，列举了抗干扰的措施和在生产实践中取得的成绩。     

浅谈测温过程检测仪表的信号干扰及抑制措施

生产实践中，过程参数的准确测定和适时调整对系统正常运行关系重大；但过程检测仪表常常易受到外部电磁场的干扰，从而影响测试结果。文章以现代化水泥生产线测温过程检测仪表各种干扰信号的消除为例，详细介绍了这些干扰信号的消除方法和具体措施。其中，对于横向干扰，可采用屏蔽接地和加滤波器消除干扰；而对于纵向干扰，可选择平衡法和隔离法消除干扰。     

Strong and Flexible Carbon Fiber Fabric Reinforced Thermoplastic Polyurethane Composites for High‐Performance EMI Shielding Applications

Electromagnetic shielding materials play a significant role in solving the increasing environmental problem of electromagnetic pollutions. The commonly used metal‐based electromagnetic materials suffer from high density, poor corrosion resistance, and high processing cost. Polymer composites exhibit unique combined properties of lightweight, good shock absorption, and corrosion resistance. In this study, a novel high angle sensitive composite is fabricated by combining carbon fiber (CF) fabric with thermoplastic polyurethane elastomer (TPU). The effect of stacking angle of CF fabric on EMI shielding performance of composite is studied. When the stacking angle of CF fabric changed, the electromagnetic interference (EMI) shielding effectiveness (SE) of CF fabric/TPU composite can reach a maximum of 73 dB, and the tensile strength can reach 168 MPa. In addition, the composite has anisotropic conductivity, which is conductive along the plane direction and nonconductive along the thickness direction. Moreover, the CF fabric/TPU composite manifests exceptional EMI‐SE/density/thickness value of 383 dB cm² g^?1, which is higher than most of current EMI shielding composites reported in literature. In summary, CF fabric/TPU composite is an excellent EMI shielding material that is lightweight, highly flexible, and mechanically robust, which can be applied to the field of aerospace and some intelligent electronic devices.     

刍议变频器谐波干扰的形成及对策

主要介绍了变频器谐波干扰形成的机理、干扰传播的途径,初步讨论了谐干扰的危害,在此基础上提出了谐波抑制和治理的有效措施。随着我国经济的发展和科技的进步,对变频器的使用越来越广泛,因此重视变频器的EMC要求,以适应更广泛的工业现场环境,提高系统的工作可靠性已经成为变频调速系统在实际应用中的一个关键问题。     

Waste cotton Fabric/MXene composite aerogel with heat generation and insulation for efficient electromagnetic interference shielding

Electromagnetic interference (EMI) shielding materials have become more and more indispensable due to serious electromagnetic-radiation pollution. Herein, waste cotton cellulose aerogels were prepared by dissolving waste cotton fabrics (WCF) in NaOH/urea aqueous solution, and MXene nanosheets were subsequently deposited on the cellulose aerogels by a facile dip coating method to obtain WCF/MXene composite aerogels. The WCF/MXene composite aerogels with highly porous network structure show remarkable electrical conductivity (8.2 Ω/sq of surface resistance), high EMI shielding effectiveness (EMI SE) in the range of 2–18 GHz (39.3–48.1 dB). The WCF/MXene aerogel possesses high SSE and SSE/t of 677.94–829.74 dB cm³ g^?1 and 3512.62–4299.17 dB cm² g^?1, respectively (2–18 GHz). In addition, the heating temperature of WCF/MXene composite aerogels reaches 199 °C when 3 V positive voltage is applied on them. The WCF/MXene composite aerogels possess excellent electromagnetic shielding effectiveness, heat generation property and insulation, which can be potentially used as multifunctional materials for EMI shielding, electrical-heating and high temperature protection.     

Enhancing Signal Output and Avoiding BOD/Toxicity Combined Shock Interference by Operating a Microbial Fuel Cell Sensor with an Optimized Background Concentration of Organic Matter

In the monitoring of pollutants in an aquatic environment, it is important to preserve water quality safety. Among the available analysis methods, the microbial fuel cell (MFC) sensor has recently been used as a sustainable and on-line electrochemical microbial biosensor for biochemical oxygen demand (BOD) and toxicity, respectively. However, the effect of the background organic matter concentration on toxicity monitoring when using an MFC sensor is not clear and there is no effective strategy available to avoid the signal interference by the combined shock of BOD and toxicity. Thus, the signal interference by the combined shock of BOD and toxicity was systematically studied in this experiment. The background organic matter concentration was optimized in this study and it should be fixed at a high level of oversaturation for maximizing the signal output when the current change (ΔI) is selected to correlate with the concentration of a toxic agent. When the inhibition ratio (IR) is selected, on the other hand, it should be fixed as low as possible near the detection limit for maximizing the signal output. At least two MFC sensors operated with high and low organic matter concentrations and a response chart generated from pre-experiment data were both required to make qualitative distinctions of the four types of combined shock caused by a sudden change in BOD and toxicity.     

原子吸收光谱分析中的干扰因素及消除方法

原子吸收光谱分析法是现今广泛使用的一种测定样品中金属含量的分析方法,但是在原子吸收光谱分析的过程中可能存在几大干扰:光谱干扰、化学干扰、物理干扰和电离干扰。本文阐述了原子吸收光谱分析法的的优缺点,论述了原子吸收光谱分析法中常见的几种干扰产生的原因,并说明了其相应的抑制和消除的方法。     

Highly Uniform and Stable Transparent Electromagnetic Interference Shielding Film Based on Silver Nanowire–PEDOT:PSS Composite for High Power Microwave Shielding

Electromagnetic interference (EMI) shielding materials, especially ones with excellent shielding effectiveness (SE), high optical transmittance, long-term stability as well as high uniformity, are urgently desired to meet the requirements of many applications. Herein, an extremely transparent, stable and uniform silver nanowire (Ag NW)–poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composite film as an EMI shielding material is prepared, which possess excellent shielding capability to both small signal and high power microwaves (HPM). The composite film exhibits SE of 30.5 dB in the frequency range of 1–12 GHz (small signal) and simultaneously has an optical transmittance of 91.0%. The SE continuously increases to 41.4 dB, while the optical transmittance still maintains at 81.1%. The composite film is very uniform, and its SE is almost unchanged even when exposed in air for a year. The SE of this composite film under the excitation of HPM is also thoroughly investigated. The HPM SE is much larger than that of small signal. As the power density of HPM is increased, the SE firstly remains unchanged, then continuously increases, and finally saturates. The SE exceeds 50 dB with the excitation power density of 40 W. More interestingly, the SE is saturated at a fixed HPM power density.