The paper presents an algorithm which allows to reduce measurements’ inaccuracy of an instantaneous values of currents and voltages in electrical networks. The considered approaches are used in the prototype stand for the non-sinusoidal power flows modeling based on LabVIEW programming environment using the facilities of modules NI-9225 and NI-9227. Experiment was performed to model non-sinusoidal load flow on the prototype stand for a simple AC 10 kV closed network.
The work proposes and analyses a new low cost method of measurements synchronization in electric low-voltage networks. The method is based on a finding the maximum factor of correlation among (between) the graphs of frequencies variations. The efficiency of the method has been tested on acting 0.4 kV feeders by field synchronous measurements. Timing accuracy of measurements’ synchronization for low-voltage networks via the suggested method is not worse than 3.5-70 µs.
The work results from the research of PPS-signals mistiming derived from SEA 9724 and NI 9467 GPS receiver modules. Effect of the number of satellites being tracked and tracking time has been studied. The mistiming value does not exceed PPS 0.1 µs at number of satellites greater than 5 for SEA 9724 and greater than 3 for NI 9467. It is proposed to use the value of co-ordinates as the initial information which will allow oscillating PPS at the number of satellites fewer than 4.
The paper is focused on time base frequency measurement of high resolution digitizers with resolution up to 16 bits without an external output of the time base signal.
The possibility of measuring both time-domain and frequency-domain response on small soil samples would allow one to predict the influence of such soil on various types of mine detectors without field trial. We have measured the time-domain soil response on standard cylindrical samples. The time response to abruptly removed magnetic field is similar to 1 / t x , where x is between 1.1 and 1.3. We have also measured frequency-domain response in the 400 Hz to 480 kHz band by various independent methods and compared with values calculated from the time response. This study shows that for soils...
Electric circuit parameter estimation from its impedance frequency response is becoming increasingly important due to the wide range of applications that it finds both in science and industry. This paper presents a comparison of the performance of a genetic algorithm and the complex non-linear least squares implemented in the LEVM/LEVMW software in the estimation of impedance circuit parameters. The comparison is focused on the standard deviation of the estimated values, convergence rate and execution time of each algorithm.
This paper compares two different magneto resistive sensor technologies used on the same configuration of eddy current testing probe. Two dimensional testing results on a friction stir welding aluminum joint were used to compare spin valve and magnetic tunnel junction sensors. These results showed that, magnetic tunnel junction sensors, provided a significant improvement on the signal to noise ratio and signal amplitude over spin valves.
This paper describes an equipment being developed at the Department of Electronics and Measurement of the Faculty of Applied Informatics of Tomas Bata University in Zlin that is designed to process measurements of shielding efficiency of composite materials according to standards MIL-STD 285 and IEEE Std. 299-2006. This kind of measurement is demanded by aircraft industry that develops new, lightweight materials for construction of aircrafts with reduced weight and dimensions and increased number of electronic devices. Besides the fact, that it is necessary to ensure mutual electromagnetic...
The Hall-effect based Teslameters (also called Gaussmeters) are the mostly applied instruments for measuring DC and AC magnetic flux densities in modern science and industry. This paper gives an overview of commercially available Teslameters at the high-end performance level. The Teslameters have been evaluated by following characteristics that are published by suppliers: probe dimensions, magnetic field sensitive volume, accuracy, magnetic resolution, measurement range, frequency bandwidth, temperature coefficient sensitivity, and price/performance ratio. The Teslameter that best matches...
Liquid impedance measurements based on capacitive (or contactless) electrodes overcome electrode polarization problems but are affected by stray capacitance from the material being measured to ground, the same as measurements with direct-contact electrodes. This study shows that the effects of that capacitance depend on the impedance being measured and for bipolar impedance measurements they increase when the ratio between that stray capacitance and electrode capacitance increases.