浅谈对感性负载消耗电能的两种错误计量

在三相交流电路中,通常采用感应系电能表或交流电子电能表测量其电能。对于三相三线电路,使用三相三线有功电能表或两只单相电能表;对于三相四线制电路,使用三相四线制有功电能表或三只单相电能表都能对电路消耗的电能进行正确计量。可是在日常工作中,我们经常发现一些农村基层供电站,在对单相电焊机(接线电压)等不对称感性负载所消耗的电能进行计量时,有的采用一块单相电能表,有的采用两块单相双向记数电能表进行计量,笔者认为以上这两种计量方法都是错误的。在三相四线制电路中,电路为正相序,作为电焊机这种感性负载,若用三相四线制电能表…     

箱式变电站投运前核相异常的分析探讨

新建、改建、扩建后的变电所和输电线路投运前必须进行三相电路核相，以确保输电线路相序与用户三相负载所需求的相序一致。当三相电路相序不一致时，须对相序进行分析，通常运用的是向量图分析法，该方法须相关技术人员具备一定的向量知识和分析能力，而本文通过余吾煤业400KVA箱变核相时出现的问题进行了分析，提出了新式核相方法—对应法，并验证了此方法的可行性。     

排除三相电能表潜动小技巧一例

现象:某DT10型三相电能表,严格按照检定规程检定合格,在校验台上不存在潜动现象。接入低压用电线路后,正潜动现象明显,不用电情况下,18小时走字0.3kW·h(不存在漏电现象)。原因:接入电能表的三相火线相序不合理。排除:变换某两根火线进线次序即可。探讨:三相电压电流相序改变后,在电能表内部空间,由某些电磁力产生的附加力矩改变方向,也就改变了对驱动力矩的数量关系,引起了电能表相序附加误差或电能表潜动。这种改变对单转盘的电能表影响尤其明显。为减少相序改变带来的附加误差或消除潜动现象,要从完善电能表内部构件着手,采用特种结构…     

零线断接对三相四线电能表计量影响机理分析北大核心CSCD

针对三相四线线性电源电能表在断接零线的情况下,存在相电压计量值偏高导致计量误差的问题,从三相电路的工作过程出发,探究了电能表零线端子电位漂移的变化规律。从理论上分析了三相四线电能表在零线断接情况下计量电压偏高的原因,并通过仿真和实验验证了理论分析的准确性,提出了一种监测零线电流的方法来识别零线断接,为识别零线断接、提高计量准确性提供了充分的理论支撑。     

基于DSP的一种三相电路谐波电流检测算法

为能用数字信号处理器(DSP)实现三相电路的谐波电流检测,从基于瞬时无功理论的一种谐波电流检测方法出发,分别讨论了三相电流中谐波正序和谐波负序分量检测的数字方法,由此得出了一种实时的谐波电流检测算法.该算法能准确地检测出三相电流中的谐波正序和谐波负序分量.当有源电力滤波器(APF)等装置的谐波电流检测电路采用该算法时,可根据需要适时调整DSP程序来形成不同的参考电流,以便更好地满足APF的不同补偿要求.仿真和实验研究结果表明了该算法的有效性和可行性.     

三相电子式多功能电能表相对误差现场在线校验方法探讨

本文主要介绍0. 5S级和0. 2S级三相电子式多功能电能表投入运行中的三相电压、电流相序和有功计量相对误差技术要求,现场在线校验方法和校验结果处理。     

多用户静止式电能表的特性和检测方法探讨

多用户电能表由于多户共用部分线路电压分户供给方式，产生了不同于普通电子式单相和三相电能表的误差影响量，可归结为相间影响、断相影响、户间影响，并且提出相应可靠的检测方法。     

电子式三相三线电能表A相失压后电量的追补

通过一例电子式三相三线电能表A相失压后,电量追补的分析和计算,使我们认识了电子式三相三线无功电能表计量原理的特点;当电子式三相三线电能表不正常工作时,电量的退补不仅与计量的主回路有关,而且还与表内二次回路有关。     

重力波检测实验装置

介绍了作者研制的重力波检测实验装置的组成，功能和接口电路。该系统具有结构简单，检测准确率高等特点。     

相序的测量方法

相序的测量方法于逢林（浙江省工业设备安装公司杭州３１０００８）０相序的概念在三相交流电力系统中，各相电压或电流依其先后顺序分别到达最大值，即瞬时值的次序，称为相序。当它们分别达到最大值的次序为Ａ、Ｂ、Ｃ时，称为正（顺）相序，而次序为Ａ、Ｃ、Ｂ时，则称...     

嵌入式相电检测及相序调整系统设计

针对许多行业有三相电相序与安全生产的要求,设计了基于32位ARM9处理器芯片S3C2410X的嵌入式系统,并移植了Linux操作系统来提高系统多任务与实时响应能力.介绍了该系统各硬件模块设计和软件设计流程,硬件模块由相电检测、相序调整、人机交互及TC35i报警等模块构成.该系统可对"三相四线制"供电端口进行相电检测与相序调整,在出现异常时执行报警操作并短信或者电话通知到负责人员,可应用于压缩机、风机和三相电机等装置的供电,特别适用于大型的移动供配电设备.     

关于电源火零线反接报警电路的分析

介绍4种关于电源火零线反接的检测、报警电路的设计方案,并分析比较各方案的优缺点。     

直流电源的监测装置

本文介绍了一种最新研制的直流系统电源设备的监测装置，即直流电源电压及直流回路漏电流监测，利用磁调制原理，在无须断开支路工作电源，不影响操作回路工作状态下，自动巡回测量各支路上每个蓄电池两端的电压及支路漏电流，当电压低于限定值或漏电流超过允许值时，自动报警同时显示有关信息。     

A New Type of Q Meter Using Variable-Width Pulse Excitation

There are several well-known methods of measuring the Q of a resonant circuit, each with its limitations. Errors are introduced into measurements of high-Q values due to loading effects and radiation losses. A theoretical basis for the development of a Q meter which will not load a high-Q resonant circuit has been established. This new type of Q meter will use variable-width pulse excitation in lieu of sinusoidal excitation and will use elapsed-time Q-measurement techniques. It is seen that if the width of the exciting pulse is known, the resonant frequency of the resonant circuit can be directly determined. A Q meter using this approach will actually yield more information about a resonant circuit than can be determined using presently standard-type Q meters and will yield this information well beyond the Q and frequency capabilities of today's Q meters.     

A high resolution digital frequency meter for low frequencies

A digital frequency meter using frequency multiplication is described. It can be used in utility power system control centers and other low-frequency applications where resolutions of the order of 1/100 Hz and almost instantaneous readouts are essential. Possible improvements of the circuit are suggested     

Bridge Circuit for Measuring Differences of Current or Voltage from a Preselected Value

A bridge circuit has been developed, using a Zener diode, which enables measurement of small changes in current or voltage from a preselected value. The circuit features increased sensitivity over a meter whose range includes the total current and is more easily used than a balanced bridge or potentiometer. The design equations are developed and the design procedure outlined for both the current and voltage difference measuring bridges, while a sample calculation is made for the current change measuring circuit. A bridge similar to that in the sample calculation was built and tested. The test circuit displayed less than 1 per cent nonlinearity of meter current vs change of input current for the design region of 460±5 ma. This shift was attributed to a slight heating of the Zener diode or a resistor at the higher test currents, but since the diode used in the test circuit had a smaller power rating than the type originally intended for use, it is not considered to be a serious limitation.     

Simple liquid nitrogen level monitor using copper wire as a sensor

A simple, compact and reliable liquid nitrogen level monitor is described which uses fine copper wire for continuous monitoring of liquid nitrogen levels in a dewar. The monitor has an analogue meter and light emitting diodes as indicators. A level of resolution better than ± 10 mm has been achieved. Sensor construction and the sensing electronic circuit are presented. The monitor incorporates an automatic liquid nitrogen refill system and remote shut-down of high voltage bias supply to the detector. Also built into the system is an alarm which sounds when the liquid nitrogen level is unacceptably low or the supply is exhausted.     

实用的出租车计价器计程适配器

适配器是由电路总成和输入、输出屏蔽导线组成的。其承担解决信号采集、电路兼容、信号电流过载、分频、功率输出、抗干扰等问题，这就保证出租车计价器和速里表原有的计量性能。其特点由10个分频参数可供选择；可使用于不同类型的出租车和计价器；经长期实用考察证明性能稳定可靠。     

Reactive Power Meter for Nonsinusoidal Systems

This paper describes a novel reactive power meter realized by electronic circuits that determine successively the terms of the equation Q = ?n=1?VrIrsin?r for n significant harmonics. The harmonic contributions to the total reactive power is determined by electronic simulation of the mathematical expression that sets the orthogonal condition of two functions in a periodical interval. Partial reactive power with its sign are stored and added in a circuit to get at the end of the cycle the total reactive power. A control system permits operation in a repetitive form.     

声波测井压电换能器多频点阻抗匹配技术研究

针对声波测井压电换能器的多频点阻抗匹配技术展开研究,首先采用多模态等效电路精确描述了换能器的导纳特性;然后通过分析多模态阻抗匹配理论,设计电感-电容复合阻抗匹配网络,并结合换能器等效电路进行参数优化和电路仿真。实验表明,相比于换能器没有阻抗匹配的测试结果,该阻抗匹配技术可大幅提高换能器在谐振频率附近多个频率处的有功功率,频带内的有功功率平均提高了30倍,从而改善换能器的激励带宽和激励效率,提高测井仪器的适应性、探测深度和分辨率。