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本文对直流比较仪比例误差的测量问题进行了探讨和分析,介绍了4种测量方法及误差理论分析,结果表明换位式电压比对法适用于测量精度低于1×10~(-5)的直流匝比仪器,电流对按法适用于测量精度低于1×10~(-6)的直流匝比仪器。而小电流测差法、调制电压法适用于测量精度低于1×10~(-7)的直流比较仪,其中调制电压法是一种很有应用前景的测量方法。 相似文献
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本文叙述了一种基于电流比较仪原理构成的能十分方便在10千伏下测量一端接地试样(反接法)的介质损失角(tgδ)和电容量(c)的高压电桥。由于它具有比传统使用的西林电桥有更大的优越性,在八十年代中它将有可能替代高压西林电桥为电力系统广大的用户服务。 相似文献
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为了解决现有电流比较仪校验方法繁琐的问题,本文提供了一种电流比较仪校验的新方法及其校验装置,并给出了该方法的计算公式和校准数据.采用本文的技术方案,仅依靠一台参考电流互感器即可进行一台电流比较仪误差的自校准,从而实现了比例(k:n)(k为小于n的自然数)的自耦式电流比较仪自校验. 相似文献
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电流互感器(CT)被广泛应用于电流的比例变换,但其准确度一般难以优于0.01%。具有更高准确度的电流比例变换装置,例如双级电流互感器或补偿式电流比较仪,由于使用上的限制,一般只用于工频电流比例的量值溯源或量值传递。针对于此,研发出一种利用电子线路补偿铁心励磁电流的即所谓电子补偿式电流比较仪(ECCC)。文中阐述这种电流比较仪的基本原理,理论分析其误差性能,并进行了误差校准试验。试验结果表明,该ECCC的准确度满足0.000 5级要求,既可作为一种高准确度的电流比例标准,也可用于工频电流的高准确度测量。 相似文献
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电力设备直流电阻测量用恒流源研究 总被引:11,自引:1,他引:11
介绍了一种用于测量大型电力设备(如电力变压器)支流电阻的高稳定度10A恒流源的工作原理、设计方法和重要性能指标,并提出了利用直流比较仪对大电流恒流源(测量微小电阻时)进行校验的新颖方法。 相似文献
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A current-comparator technique is applied to several auxiliary instruments which enables accurate high voltage power measurements to be made at very low power factors using precision wattmeters and precision bridges. The instruments include a high-voltage active-divider with a nominal output voltage of 100 V, a high-voltage inductive-quadrature-current reference source with current output ranges of 1 mA, 2 mA, and 10 mA, and a high-voltage high-capacitive-quadrature-current reference source with current output ranges of 0.1 A, 0.5 A, and 1 A. The current comparator is used in a feedback loop to correct the magnitude and phase of the associated outputs of these instruments to an accuracy of better than ±10 ppm (parts per million) and ±10 ?rad respectively. 相似文献
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A current-comparator technique for obtaining a load-loss standard with adjustable loss tangent (or power factor) for in-situ calibration of transformer loss-measuring systems is described. The standard, driven by the test voltage through a low-loss, high voltage compressed-gas-dielectric reference capacitor, simulates an inductive load that can be operated with load currents of up to 1000 A. The equivalent rating of the load is determined by the voltage of the high-voltage reference capacitor. Adjustment of the loss tangent (or power factor) is achieved by comparing the load current, using the current comparator, with in-phase and quadrature reference currents derived from the test voltage. The standard features three current ranges of 10 A, 100 A, and 1000 A. The maximum current of each range is available at five different voltage levels which are determined by the voltage rating of the high-voltage reference capacitor. The standard also features a direct-reading loss tangent (tan δ) adjustment in the range from 0 to 0.1 with five-digit resolution and an accuracy of better than 20 parts per million 相似文献
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A current-comparator technique for obtaining a wattmeter for accurate high voltage power measurements at very low power factors is described. The quadrature component of the load cturrent is automatically balanced in the current comparator against a quadrature current obtained from a slave supply, thereby reducing the stringent high accuracy requirement of the wattmeter when used for measuring power at very low power factors. The current-comparator-based wattmeter has an estimated accuracy with respect to its readings of better than 3 percent at 0.001 power Factor, 1 percent at 0.005 power factor, and 0.5 percent at 0.01 power factor and higher. It features an internal high-voltage active-divider and displays to indicate source voltage, current, power factor, and reactance of the load, in addition to the power. 相似文献
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A microprocessor-controlled high-voltage current-comparator-based capacitance bridge is described. The bridge has a capacitance ratio and a dissipation factor (loss tangent) measurement range of 1/1 to 100/1 and 0 to 10%, respectively, with a resolution of 1 PPM (part per million). To accommodate capacitance ratios larger than 100/1 (up to 100000/1) and load currents of up to 1000 A, an additional range-extending two-stage current transformer is employed. The overall accuracy of the bridge including the ratio extender is better than 5 PPM in both magnitude and phase. The automatic balancing feature facilitates the use of the bridge for accurate load loss measurements of large high-voltage inductive loads, such as shunt reactors and power transformers. It allows tracking of the changes in the inductive and loss tangent balance due to power frequency fluctuations and heating effects, respectively 相似文献
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文章介绍了国内外随桥梁敷设高压电缆现状以及国内相关规程规范,对在武汉市城区随桥敷设高压电缆进行了主要技术因素分析、利弊分析以及工作设想。 相似文献
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沈文琪 《电力电容器与无功补偿》2006,(6)
详细说明了利用高压西林电桥和高压标准电容器测量电力电容器的电容和介质损耗角正切(Tanδ)的原理;扩大量程的途径及注意事项;引起测量误差的因素以及如何消除或减小测量误差,提高测量精度的方法。同时还简要介绍了通过测量全膜介质电力电容器的损耗功率求得全膜介质电力电容器的Tanδ值的方法。 相似文献
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An overview of the development of instrumentation and measurement techniques at the National Research Council of Canada, based on current comparator technology, for calibration of nonconventional instrument transformers with nonstandard rated outputs, is presented. The instruments include: (1) a wide-dynamic-range transimpedance amplifier for operation of input currents from 1 A to 1000 A with means for modifying the in-phase and quadrature components of the output voltage (rated 10 V) within a ±10% range; (2) a high-voltage high-current transconductance amplifier with output current ranges of 10 A, 100 A, and 1000 A; and (3) a voltage ratio standard also with means for modifying the in-phase and quadrature components of the output voltage (rated 100 V) within a ±10% range. The current comparator technique is used to obtain accuracies of better than 20 parts per million in both magnitude and phase of the associated outputs of these instruments 相似文献
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提出了一种宽电压范围输出的三电平DC/DC变换器,其包含两组并联的主桥臂和辅助桥臂以及级联形式连接的主变压器和辅助变压器。该变换器具有低压低功率和高压高功率两种工作模式,其中低压模式下辅助桥臂不开通以降低电路损耗,高压模式下辅助桥臂开通以提高输出电压。与传统电路相比,变压器具有更低的变比,分析了传统拓扑的损耗,并比较了新拓扑与传统拓扑在不同输出模式下的效率,得出新拓扑在低压模式下具有更高效率的结论。研制了一台2 000 W的原理样机,实验数据表明,在低压模式下新拓扑的效率仍可高达94%,较传统拓扑提升了3%,验证了理论分析的正确性。 相似文献
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研究了一种具有高压隔离性能的多路输出驱动电源。利用全桥串联谐振在桥臂间形成电流型交流母线,配合高压电缆线、光纤传输实现高压隔离性能。利用磁环数目的增减可以灵活控制驱动电源输出路数。分析了该电源的适用环境、结构及其特点,分析了部分参数对驱动电源输出电压的影响并进行了仿真,验证了该驱动电源配合IGBT运用在轻型高压直流输电中的可行性。最后,制作了一台125 W/2.5 A的样机,进行了实验验证。实验证明,该驱动电源结构、控制简单,可以实现软开关,符合多路输出以及高压隔离中驱动的要求。 相似文献