三相四线电能表错误接线对电能计量影响分析

根据三相四线有功电能表电能计量原理,结合向量图,分析在错误接线下三相四线有功电能表电能计量与正确接线时的误差值,并采用三相电能表校验装置,对错误接线下的三相四线有功电能表的实际电能计量性能进行验证,对处理实际由于错误接线引起的电能纠纷提供参考。     

关于电能表计量校验中应注意的问题

随着社会的发展,人们对电能的依赖越来越严重,随着电能在人们生活生产中的应用,使得人们的生活生产水平得到了大幅度提高。而在电能的使用过程中,还必须要运用一定技术手段或者仪器对电能进行计量收费,从而才能使电力企业的资金得到回笼,才能够促进电力事业快速稳步的发展。在当前的电能计量中,采用电能表进行电能的计量是当前最主要的计量方式,同时也是实用的计量方式。采用电能计量表进行电能的计量,不仅确保了电能计量的准确性和效率,还促进了我国电力事业快速稳步的发展。然而就目前电能量的实际情况而言,在电能计量校验中还存在着一定的问题。因此为了进一步提高电能表的准确性和效率,加大对电能襄计量校验中存在问题的分析研究力度不仅意义重大,而且迫在眉睫。本文通过对电表计量校验的深入研究,然后对其中应注意的问题及应对措施进行了详细阐述,以供同行参考。’     

电压在高压电能计量中的影响

针对在高压电能计量中，当电压互感器一次保险故障时，电能表将不能反映电能的实际消耗的问题。对电压发生异常时机械表和电子表电能计量进行对比，说明电子式电能表的优越性。     

电能计量技术的回顾与展望

如何准确地计量电能 ,如何确保电能量值传递的准确可靠 ,对整个国民经济及社会发展都有着深远的意义。回顾电能计量事业的发展 ,经历了一个漫长而艰辛的过程。本文将对近二十年来电能计量技术的发展作一个概述。一、电能表电能表作为电能计量的主要工具 ,已渗入到国民经济的各个领域。５０年代宝鸡市使用的电能表均为感应式电能表 ,重要的计量点采用进口表 ,如宝鸡电厂使用匈牙利产的电能表 ,其他则采用基于前苏联标准生产的电能表如ＤＳ１型２ ０级有功电能表及ＤＸＩ型３ ０级无功电能表 ,一直使用到８０年代初期。８０年代中期开始使用我…     

加强电能计量分析降低发电厂电量损失

分析发电厂厂损电量变化原因的主要途径之一是调查分析电能表计量是否正常.文章在介绍影响关口电能计量的主要因素和电能计量管理实例分析的基础上,提出了做好电能计量管理工作的措施.     

谐波对电能计量的影响

叙述电网谐波的主要来源,分析了谐波对电能计量的影响。研究结果表明:感应式电能表的误差频率特性曲线呈迅速下降趋势,当谐波含量较大时对其电能计量将会产生较大的影响;而电子式电能表的计量误差受频率变化影响较小,具有较宽的频率响应,误差频率特性曲线较为平坦,在谐波存在下以全能量为计量标准时,电子式电能表的计量误差远远小于感应式电能表的电能计量误差,而以基波能量为计量标准时,电子式电能表的计量误差比感应式电能表的计量误差大。此外,作为谐波源,非线性负荷所产生的谐波是吸收基波的一部分转化而来,基于传统的计量方式具有不合理性,因此针对该情况,提出相应的解决方法和对策以及一种新的电能计量方式。     

谐波对电能计量的影响

叙述电网谐波的主要来源,分析了谐波对电能计量的影响。研究结果表明：感应式电能表的误差频率特性曲线呈迅速下降趋势,当谐波含量较大时对其电能计量将会产生较大的影响;而电子式电能表的计量误差受频率变化影响较小,具有较宽的频率响应,误差频率特性曲线较为平坦,在谐波存在下以全能量为计量标准时,电子式电能表的计量误差远远小于感应式电能表的电能计量误差,而以基波能量为计量标准时,电子式电能表的计量误差比感应式电能表的计量误差大。此外,作为谐波源,非线性负荷所产生的谐波是吸收基波的一部分转化而来,基于传统的计量方式具有不合理性,因此针对该情况,提出相应的解决方法和对策以及一种新的电能计量方式。     

电力系统中电能计量技术浅谈

在电力系统中,从发电系统到供电系统,最后到用电户,中间都需要进行电能计量,我们把电能表、与电能表配合使用的互感器以及互感器到电能表之间的二次回路连接线,称为电能计量装置。笔者针对抄表技术、防窃电和反窃电技术,阐述一些个人见解。     

计量自动化系统在计量管理工作中的应用

计量自动化系统实现了电能表运行情况和计量故障信息实时监控,电能量各类统计、分析,电网线损分压、分区、分线统计,变压器损耗电量、母线不平衡率的分析计算.对计量管理、决策和工作的开展提供了非常重要的技术依据.     

远传通信在电能计量中的应用

电能计量的方法主要有两种 :一种是使用电能表计量 ;另一种是使用功率变送器计量。前者性能稳定 ,寿命长 ,适用于电量结算。后者瞬态响应好 ,适用于监视高峰负荷、高峰电量。使用远距离计量时 ,采用带输出脉冲信号的电能表 ,根据用电量的多少 ,输出稳定的脉冲数量 ,脉冲信号再输入单片机进行计量。功率变送器的信号也可以输入单片机进行计量。目前 ,我厂电能结算采用电能表数据。 1 989年投入了大量的资金对一级计费电能表进行了全面改造 ,全部使用新型带脉冲信号输出的电能表。由于近几年地下电缆老化 ,线间绝缘电阻下降 ,导致信号无法传输…     

Photostriction of CH3NH3PbBr3 Perovskite Crystals

Organic–inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light–matter interactions. The photoinduced strain of CH₃NH₃PbBr₃ is investigated using high‐resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH₃NH₃PbBr₃ is calculated as 2.08 × 10^?8 m² W^?1 at room temperature under visible light illumination. The significant photostriction of CH₃NH₃PbBr₃ is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation–rotation coupling. Unlike CH₃NH₃PbI₃, it is noted that the photostriction of CH₃NH₃PbBr₃ is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH₃NH₃PbBr₃ for applications in next‐generation optical micro‐electromechanical devices.     

Constitution of the Ni3Cr-Ni3Al-Ni3W system

Isothermal sections of the Ni-Cr-Al-W system have been investigated at 75 at % Ni and temperatures of 1523 and 1273 K, by means of phase compositional analysis, X-ray diffraction and microscopical examination. The alloys studied lay in the range 2.5 to 10 at % Cr, 12.5 to 20 at% Al, 2.5 to 6.25 at % W, The phases formed were, and the bcc solid solution based on tungsten (designated ₂). The maximum extent of the region was found to be 3 at % each of chromium and tungsten. Preferential partitioning of tungsten to occurred. Study of an Ni-10Cr-12.5Al-2.5W alloy aged at 1273 and 1073 K, after quenching from 1573 K, showed that changes in and compositions and lattice parameters occur as a function of ageing time.     

(La2/3Ca1/3)(Mn(3-x)/3)Fex/3)O3体系磁电阻行为的研究

通过系统地测量（La_2/3Ca_1/3）（Mn_{（3-x）／3}Fe_x／3）O₃（x＝0、0.1、0．2、0．3的体系样品的电阻率-温度关系以及一定温度下磁电阻率与磁场的关系,发现随x的变化其磁电阻率峰和电阻率峰均发生位移,磁电阻率峰值增大,并伴生磁电阻率峰展宽效应．作者认为由于Fe的替代,引起体系中Mn³⁺／Mn⁴⁺比率及磁矩的变化,加之外场对磁有序结构的调制作用,从而影响了Mn³⁺－O^－Mn⁴⁺的双交换作用,最终导致磁电阻行为发生变化．     

PbZrO3-CdTiO3 solid solutions

The structural, nonlinear optical, and dielectric properties of (1-x)PbZrO₃ ·xtCdTiO₃ solid solutions were studied. The phase relations in the composition rangesx = 0–0.3 and 0.85-1.0 were established. The results suggest that the ferrielectric ordering in CdTiO₃ persists up to 730 K.     

Phase equilibria in the system LaMnO3 + δ-SrMnO3-LaFeO3-SrFeO3 − d

We have revealed the formation of a continuous series of orthorhombic LaMn_{1 ? y} Fe_yO₃ solid solutions (0<y<1); La_{1 ? x} Sr_xFeO₃ solid solutions in the composition range 0 < x ≤ 0.8, with an orthorhombic structure at 0 < x ≤ 0.6 and a cubic structure at 0.6 < x ≤ 0.8; and a tetragonal SrMn_{1 ? y} Fe_yO₃ phase in the range 0.6 ≤ y ≤ 1. The composition stability limits of the perovskite phase La_{1 ? x} Sr_xMn_{1 ? y} Fe_yO₃ have been determined, and the 1100°C isotherm of the La₂O₃-SrO-Mn₃O₄-Fe₂O₃ system in air has been constructed.     

Multicolor up-conversion emissions of Tm3+/Er3+/Yb3+ tri-doped YF3 phosphors

Tm3+/Er3+/Yb3+ tri-doped yttrium fluoride (YF3) phosphors were prepared by a facile hydrothermal method. X-ray topographic analysis found that the phosphors were crystallized products. Their sizes and morphologies were characterized by scanning electron microscopy (SEM, Hitachi S-4800), which indicated that most of the YF3 phosphors were hundreds of nanometers in size. Up-conversion (UC) spectra were recorded under 980-nm diode laser excitation at room temperature with a fluorescence spectrometer (Hitachi F-4500). Plenty of UC emissions of Tm3+ and Er3+ were observed from ultraviolet to red. For Tm3+ ions, a five-photon process (approximately 291 nm and approximately 347 nm), a four-photon process (approximately 362 nm and approximately 452 nm), and a three-photon process (approximately 475 nm) were identified in the UC spectra. The UC emissions from the Er3+ were: approximately 380 nm, approximately 408 nm, approximately 521 nm, approximately 537 nm, and approximately 652 nm. Therefore, cyan-white light can be observed by the naked eye at 980-nm excitation, even under low excitation power density. By comparing the UC spectra of the phosphors annealed at different temperatures, we found that the intensity of the UC luminescence increased as annealing temperature increased. Furthermore, the spectral dependencies on Tm3+ doped concentrations were studied. The energy transfer processes and fluorescence dynamics in the tri-doped system are currently being investigated.     

3 Cr3 Mo3 VNb 在热冲孔中的应用研究

高合金钢热冲孔冲头寿命关系到模具与产品成本、生产效率、自动化设备的使用,因此,应注重冲头的选材、材料制备与冲头制造工艺。 用 3 Cr3Mo3 VNb 作为高合金钢热冲孔冲头,为提高模具寿命,在材料制备上,优化了成分,采用电渣重熔冶炼,减少杂质,毛坯锻造两次,用大锻造比锻造,冲头热处理用真空炉,三次回火,热处理硬度取 HRC42 ~ 46 ,冲头表面处理采用镀铬工艺,开展了热冲孔工艺试验。 结果表明,用3 Cr3Mo3 VNb 可使冲孔冲头寿命平均达到 800 件以上。     

Processing and properties of Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramic relaxors

The shrinkage phenomenon during the reaction-sintering of PMN-PZT from low-temperature pre-reacted 3PbO + MgNb₂O₆ + PZT powder mixtures has been studied. It was assumed that the pre-reaction treatment leads to the formation of a pyrochlore phase containing very active MgO small particles, and that the strong shrinkage occurring up to 800 °C took place by the diffusion of Mg²⁺ cations into the pyrochlore phase particles, thus controlling the reaction-sintering shrinkage phenomenon. Above that temperature the densification was enhanced by a liquid-phase sintering process. The ceramics sintered at 1050 °C for 2 h showed 96% of the theoretical density, and the dielectric constant of such a sintered ceramic showed a maximum value of 17 000 at 1 kHz. It was also found that the dielectric constant decreased with increasing grain size. Although the role of PZT in enhancing the dielectric constant of otherwise low-purity PMN ceramics is not clear, the increase in K is assumed to be a solid-solution effect. The presence of impurities and the PbO stoichiometry could be influencing the not too high dielectric constant value of PMN-PZT ceramics.