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A new calibration system for automated high-voltage current-comparator-based capacitance and dissipation factor bridges is presented. It does not require synchronization circuits between the digitizers and the generators. It is possible to simulate 1:1 capacitance ratio and dissipation factors from 1.10-6 with standard uncertainties of less than to 1.10-1 with standard uncertainties of less than 1...
A digital optical fiber current transformer (OCT) based on Rogowski coil and optical fiber transmission for use in high voltage systems is described in this paper. The technologies of signal sampling, processing and communication for the optical current transformer are introduced. The paper analyzes the present supply power techniques on high voltage side, and puts forward a new closed-loop regulating...
Digital sampling measuring system was developed at NIM. AC signals under test were transmitted into the input of AD converter by voltage follower. Under the control of MCU, AD converter synchronously sampled the signal by full period, and the sampling data was transmitted by photo-coupler and calculated by computer. The sampling results compared with the measurement results of FLUKE 5790A. The agreements...
Two simulant high-power resistance standards were newly developed at NIM. The first resistance standard uses a high-power resistor for signal sampling, IVD for adjustment, and a voltage-follower for output. The high-power low-resistance resistor has similar input/output characteristic as the simulated variable and can carry more load power. The second resistance standard uses resistance network for...
We present a method for calibrating the voltage that a pulse generator produces at a load at every point in the measured waveform epoch. The calibration includes an equivalent circuit model of the generator so that the user can calculate how the generator will behave when it is connected to different instruments. The calibration also includes a covariance-based uncertainty analysis that provides the...
This paper describes a simple and easy to implement algorithm for synchronizing analog-to-digital converters to the fundamental of a continuous periodic signal. It is based on the discrete-Fourier transform (DFT) on sampled data and uses DFT- leakage detection to ensure a synchronous sampling. It may be applied to distorted waveforms in general, irrespective of the type of ADC used, and no windowing...
Weighing windows have been suggested so as to cut the error that non-coherent sampling induce in the measurement of r.m.s., power and harmonic parameters. The link between the weighing and the Swerelein algorithms is shown. The paper also presents an algorithm for finding the amplitude and phase of harmonics based on the frequency characteristic of the used window. The suggested windows allow the...
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