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This paper describes a universal digital sampling setup for measurement of a complex voltage ratio. The setup was primarily designed for calibration of a phase angle error of current shunts, but it can be used for calibration of wide range of impedance standards in full complex plane. The setup allows calibration of impedances down to submegaohm range with compare currents up to 10 A and frequencies...
A new software toolbox QWTB is presented. It aims for aggregation of high-quality algorithms required for data processing of sampled measurements. Algorithms include frequency, amplitude and phase estimators, stability quantifiers, flicker calculator etc. The toolbox unifies and simplifies user interface of algorithms and an example for every algorithm is included to help understanding. The toolbox...
This paper describes digital sampling bridge for impedance measurement up to few tens of kHz in four terminal pair definition. It is primarily dedicated for low impedance measurements with comparison currents over 10 A however it can be used at least up to few tens of kΩ as well. Achieved uncertainty for near unity impedance ratio is few μΩ/Ω and the phase angle uncertainty at 1 kHz is few μrad (coverage...
This paper describes a construction of the high current shunts of cage design up to 100 A based on known model. Investigation of dependence of their dc resistance and frequency characteristic on current level is presented and followed by improvement of the high current shunts design using active cooling.
This paper describes a simple, affordable and easily replicable 10 Ω resistance standard with calculable frequency dependence and time constant. The resistor is a bifilar type made from an enameled manganin wire. A time constant of 6.05 ns with uncertainty of 0.53 ns was calculated and verified by comparison with another calculable resistance standard. A calculated and measured ac-dc difference of...
This paper describes an investigation of single junction thermal converters (SJTC) resulting in development of a primary standard of ac-dc current difference. Frequency characteristic of the primary standard was determined by special measurement methods (low frequency method, fast reversed dc) and by a lumped element model calculation. Comparison of reference thermal converter (TC) calibrated outside...
The Phasor Measurement Unit (PMU) simulator is presented in this paper. The aim of the simulator is to calculate the uncertainty of a PMU by means of the Monte Carlo method. A whole measurement chain is modeled in the simulator, including a transducer, a digitizer and a synchrophasor estimating algorithm. As an example of results of the simulator a total vector error of the modeled PMU is shown together...
This paper describes digital sampling setup for measurement of complex voltage ratio. It was originally designed for calibration of a phase angle of current shunts. However later it was successfully used for comparison of various impedance standards up to 100 Ω, calibration of buffer transfer and also comparison of inductive voltage dividers (IVD) in frequency range up to 40 kHz. Magnitude uncertainty...
Uncertainty analysis of a very simple sampling phase meter based on four parameter sine wave fitting is presented in this paper. An uncertainty of a sample time and a measured voltage is assigned to every sampled point and a total uncertainty of a phase difference is calculated by means of the Monte Carlo method. Results show the total uncertainty is lower than 0.5 millidegree for selected digitizer...
This paper describes measurement of a Q factor of the inductance standard by means of fitting a resonant curve by a model of series resonant circuit. The resonant curves have been measured on a modified automated Q meter with a remote controlled function generator and voltmeter.
A high performance THD measurement equipment based on the National Instruments NI PXI-5922 24-bit Flexible-Resolution Digitizer was developed at CMI. This paper describes the validation method and achieved results. The validation was done in two steps; in the first step a low distorted signal using ultra-pure generator was utilized. In the second step was done a validation of a high level THD measurement...
This paper describes an automated non-coherent sampling THD meter based on the 24 bit digitizer National Instruments PXI 5922. The THD meter is designed for a frequency range up to 1 MHz with analysis of the harmonics up to 6 MHz. Contrary to commercial devices developed THD meter displays a signal spectrum and gives user the possibility to evaluate impurities in the signal affecting THD calibration...
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