9762 papers found
The methodology of current density measurement in space plasma and the instrument for its realization - Split Langmuir Probe (SLP) - are discussed. An analytic approach to the investigation of SLP interaction with the surrounding plasma allowed to determine the conditions of its application and expected transfer function. Experimental evidence of SLP application efficiency is given.
The main advantages of the Rogowski coils are the Potential free measurement and the low cost compared to shunt and CT measuring systems. Usually they are applied for measuring high-amplitude or high frequency currents. The aims of the paper is to investigate a new analog signal processing able to overcome the major limitations of the Rogowski coils in low current and lowfrequency range.
This paper is concerned with the measurement of short-circuit loop impedance in electrical low voltage network with operating loads. The paper discusses and analyzes the influence of the operating network load on the accuracy of loop impedance measurement when are use classical instruments and methods. The results of analysis indicate that the effect of the operating load is significant especially when the measurement point is close to the induction motors. The paper presents the new vectorial method for measurement loop impedance in which the influence of operating loads on measurement...
Error analysis of a resistive sensor-to-microcontroller interface based on pulse width modulation (PWM) and time ratio measurement (sensor resistance over reference resistor), shows that leads resistance produce zero, gain, and nonlinearity errors. Because at the calibration points these errors are nulled out, several calibration resistors selected according to the sensor resistance range would reduce those errors in the full range. Two-point calibration and time ratio measurement yield errors smaller than 1 W for lead resistance of 10.5 W and sensor resistance from about 600 W to 3550 W,...
The paper proposes a VI-based method for the automatic determination of the mechanical characteristic of induction motors. The signals coming from an inertial start-up transient are acquired and digitally processed, instead of processing the signals from the traditional load Tests. In order to overcome the inaccuracy given by the stator winding resistance variation due to the temperature variations, the stator winding resistance is constantly measured by means of a dedicated circuit and processed together with the other signals. The results of experimental tests are shown and the method...
The work reports the measurements of the excess-noise coming from the thick-film piezo-resistors (TFRs) deposited on metallic substrates. The purpose of this paper is to single out the best combination of conductive, dielectric and piezoresistive inks in order to minimise the electronic noise. At this purpose a comparison between the excess noise measurements made of the same inks and geometric characteristics but screen printed and fired on alumina substrates, are reported. Moreover, the article gives a description of the measurement instrumentation used and, in particular, of the low noise...
Detection of mechanical and electrical faults by use the leakage magnetic field as quantity able to give evidence about state of electrical machine. Solution of problems connected with measurements on electrical machines at difficult operation conditions.
A new concept of distributed data acquisition systems using Java architecture is proposed. A connection of external modules (standard library for National Instruments DAQ board) to source code in Java is described. Next, an example of the system, that uses a communication based on sockets for remote monitoring of meteorological parameters, also via Internet, is presented.
High power electric energy receivers are loading power network, with result of light flickering, for witch the IEC standard defines a quality, measured with instruments named as flickermeters. In this paper authors’ opinion the method of flickermeters calibration misses actual network properties, so that vagueness of measurements results arises. The results of analysis and model investigations of this problem are presented.
Stability of root mean square (rms) voltage is one of more important parameters of electrical energy quality. To evaluate the stability - rather unstability of rms voltage- we use a flickermeter which determine the flickering severity factor P ST . Flickermeter is such an instrument in which reaction of electrical power is modelled by source of light onto human psychophysical features. The obtained signal is statistically analysed. As a result we obtain value P ST which is a measure of electrical energy quality. After statistical treatment of the signal we obtain the value of parameter P ST...