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找出了以ZX78型电阻箱及ZY4型双桥检验器为主标准器组成的检定装置的各误差源,并对它们进行了定理的误差分析,最后分别计算出核检定装置便携式双桥及单桥的总不确定度,从而验证了该检定装置合符JJG125-86直流电桥检定规程的要求。 相似文献
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叙述了开发检双桥用标准电阻箱检定装置及检定方法的理论基础与应用技术。并论述了检定系统的组成结构和所寻找并采用的检定方法——完全替代法和不完全替代法,对其应用结果进行了论证。其开发成功的检双桥用标准电阻箱检定装置及检定方法是正确可行的。 相似文献
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在进行电能表检定装置B类不确定度评定中,影响不确定度评定结果的主要因素是各种误差源,用电能表检定装置整体作为误差源,替代装置中测量部分分别独立的误差源,对电能表检定装置不确定度评定的影响进行分析,并通过实例说明用交流电能表检定装置标定误差替代交流电能表检定装置内部各器件误差的方法是可行的。应用结果表明:该方法在分析计算中可减少计算步骤,简化分析方法。 相似文献
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0.005级高准确度交流电流—电压变换器 总被引:1,自引:0,他引:1
研制成功的两种0.005级交流电流——电压变换器,它们与1081型或7081型数字电压表以及稳定度为0.01%的稳流电源,组成0.015级交流电流表检定装置。可采用简便的直流比较法检定0.05级及以下各种精密级交流电流表。本文介绍了该变换器的原理、线路特点并进行了误差分析。 相似文献
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电能表检定装置的误差与测量不确定度河北省电力试验研究所李艳娥根据JJG597—89(交流电能表检定装置》规程要求,电能表检定装置误差采用整体测试方法,但对准确度较高的装置或无测试手段时,也可采用综合计算法。本文主要通过对电能表检定装置各项误差源的分析... 相似文献
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介绍了QS1型西林电桥检定装置的检定系统,工作原理和误差计算,并根据极限误差的方和根法求得总不确定度,且加以验证。 相似文献
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《Education, IEEE Transactions on》1980,23(4):218-221
Of concern are the detector voltage and current of an unbalanced impedance bridge for the general case when both the source and detector impedances are finite. A convenient expression for the exact Thevenin impedance seen by the detector is derived. Several examples are given to illustrate the observation that this Thevenin impedance is barely sensitive to the source impedance. Two approximate Thevenin impedances are easily obtained, either by element combination or as limiting forms of the exact Thevenin impedance. They are nearly equal and bracket the actual Thevenin impedance. A conservative error bound is given. Algorithms suitable for programming impedance bridge problems are discussed. Also, for use with hand-held calculators, an approximate method for calculating the detector voltage and current is given. The method is direct, rapid, and accurate; it employs just one approximation?the Thevenin impedance. 相似文献
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介绍了一种性能良好的超声波换能器,在现有纵波探头基本结构的基础上,在内部增加高增益放大电路,并利用线路实现发射和接收的转变。实现了发射探头和接收探头可以互换的功能,避免了在应用中发射和接收探头用错而引起的探头损坏。 相似文献
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针对现有阻抗测量方式的不足和现实工业的需求,介绍了一种以模拟数字混合电桥为核心的阻抗测量系统。系统采用模块化设计,包括模数混合电路、单片机信号处理与通信、上位机显示与控制3部分。模数混合电路包括信号发生与调理、模拟前端、混合平衡电桥、平衡检测与控制。单片机控制着各部分电路,使电桥达到平衡,并将平衡参数上传给上位机,由上位机计算后得到阻抗。对频率、电压等参数的控制可以通过上位机与单片机通信后实现。系统实施方法较传统方法简单,成本和体积、功耗都大幅降低,具有很强的应用价值。 相似文献
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Pulsewidth modulation (PWM) control techniques for rectifiers are widely used to improve the source current waveform and the input power factor. Recently, methods to reduce the number of detectors have been studied to simplify the system configuration and control of such rectifiers. It is known that a voltage detector on the ac side can be omitted, though a voltage detector on the dc side is needed for adjustment of the dc output of a PWM rectifier. In this paper, a method for controlling a single-phase rectifier without any voltage sensor is proposed. The ac-side voltage can be estimated from the input-reactor voltage when the ac side of the bridge is short-circuited. The reactor voltage is easily obtained by multiplying the inductance of the reactor by the derivative of the source current measured. The dc side voltage can be estimated by calculating the difference between the source voltage at the beginning of every switching period and the reactor voltage sampled and held in the previous bridge conduction mode. This paper describes the control scheme, its implementation, and the performance characteristics of the rectifier. The usefulness of the rectifier is confirmed by experiment. This method is applicable to various types of PWM rectifiers. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(4): 90–96, 1997 相似文献
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本文采用比拟方法,研究设计工作在高次模TE_(21)上的园盘平面电路3dB混合电桥,提出了合理的端口位置配置方案,使得在保证原有园半径不变的情况下,中心频率可提高1.56倍左右。这不仅使该种园盘形混合电桥能适用于更高的频段,并且解决了因频率增加而使园半径过小带来的制做加工困难问题。此外,本文还采用加阻抗变换阶梯的办法,优化特性,大大增加了带宽。 相似文献
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详细介绍了用于往复驱动的微机控制无位置检测交流永磁无刷电机系统,该系统采用新型场效应晶体管作功率开关元件,组成三相桥式整流和逆变器,以PWA脉冲信号实现斩波调整整流。逆变器与电机运行于自控式变频方式,不会出现失步,电机磁场为不受电枢反应影响的恒定方波,使电流与转矩成线性关系。 相似文献
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This paper describes the theoretical foundation and prototype implementation of a power system transient event detector for use in a nonintrusive load monitor (NILM). The NILM determines the operating schedule of the major electrical loads in a building from measurements made at the electric utility service entry. The transient event detector extends the applicability of the NILM to challenging commercial and industrial sites. A spectral preprocessor for use in the transient event detector is introduced first. Then, the transient event detection algorithm is developed. The performance of the algorithm is illustrated with results from a prototype event detector 相似文献