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Jorge E. Gaitán-Pitre, Ramon Pallas-Areny
CHARGE-TRANSFER-BASED SIGNAL INTERFACE FOR DIFFERENTIAL CAPACITIVE SENSORS

We propose a circuit to directly connect a differential capacitive sensor to a microcontroller unit (MCU), which is based on the charge-transfer method and does not need any calibration component. The performance has been tested by emulating the differential capacitive sensor with discrete components. The major uncertainty sources are residual stray capacitances. The maximal deviation obtained, referred to the Full Scale Span (FSS), is ±4 % for sensors with nominal capacitance C0 = 100 pF, and ±0,6 % for sensors with C0 = 1 nF.

Jorge E. Gaitán-Pitre, Ramon Pallas-Areny
CHARGE-TRANSFER-BASED SIGNAL INTERFACE FOR RESISTIVE SENSORS

Charge transfer has been demonstrated to be a cost-effective method to measure capacitive sensors with low-end microcontrollers. Here we apply charge transfer to measure the output of voltage dividers that include a high-value resistive sensor hence extending the advantages of this method to a large group of sensors. By using two-point calibration, the maximal deviation obtained, referred to the Full Scale Span (FSS), is ±4 % for sensors between 100 kΩ and 1 MΩ, and ±5 % for sensors between 1 M? and 10 MΩ.

Maja Grbic, Dragana Naumovic-Vukovic, Aleksandar Pavlovic
CALIBRATION OF MAGNETIC FIELD ANALYZER

This paper presents a calibration of a low frequency magnetic field analyzer performed in the Calibration and Testing Laboratory of the Electrical Engineering Institute Nikola Tesla in Belgrade, Serbia. The paper describes the calibration method as well as applied reference standard for magnetic field generation. It also presents the results of the calibration with calculated measurement uncertainty. The calibration results indicate that estimated expanded measurement uncertainty is in accordance with the requirements of IEC 61786:1998.

Vladimir Vujicic, Zoran Mitrovic, Ivan Zupunski, Zeljko Beljic, Bojan Vujicic, Platon Sovilj
STOCHASTIC DIGITAL MEASUREMENT METHOD – A STRATEGIC ADVANTAGE IN ELECTRICAL POWER DISTRIBUTION SYSTEM MEASUREMENTS

Stochastic digital measurement method (SDMM) is a method that uses low resolution flash A/D converters, the most common one uses only 2 bit converters. Hence, the instruments that use SDMM are characterized by a very simple hardware, small number of systematic error sources, wide bandwidth, high reliability and robustness. The paper presents the latest results of its application in the power grid measurements. Simple hardware allows easy implementation of parallel measurements and high level of integration of functions of instruments that simultaneously measure multiple quantities – currents and voltages on the multiple channels, as well as derived quantities – power and energy.

Linus Michaeli, Ján Šaliga, Jozef Lipták, Ján Buša, Roman Cimbala
DIELECTRIC PARAMETERS ESTIMATION BY THE MEASUREMENT OF THE RELAXATION CURRENT

Paper describes new method of the estimation of the relaxation properties of dielectric materials based on the direct estimation dipole R,C parameters and from the decomposed isothermal current, which is represented by multiexponetial function. Proposed least mean squared optimization is resistant on the accumulation of error in the successive component estimation. Moreover takes into account mutual influence of parameters on the time constants and peak values of the exponential components.

Romuald Masnicki, Janusz Mindykowski
THE SYNCHRONIZATION OF PROCESSES IN REGISTRATION TRACK OF DATA FROM ELECTRICAL POWER SYSTEM

In paper, the synchronization of operations performed in registration track of the parameters from electrical power system is discussed. The synchronization operations are carried out in the track during communication between functional blocks, on several levels of these operations (bit, frame and information synchronization). The successive stages of data registration track in instrument are shown. The different ways of frame synchronization in transmission between selected blocks and some obtained effects are presented.

Gabriella Crotti, Daniele Gallo, Domenico Giordano, Carmine Landi, Mario Luiso, Davide Picco
A TECHNIQUE FOR REAL-TIME BANDWIDTH ENHANCEMENT OF INSTRUMENT VOLTAGE TRANSFORMERS

The correct measurement, over a wide frequency spectrum, of the quality of power in electrical systems is becoming an essential aspect for the verification of the compatibility of power system with electrical equipment and the identification of unsafe situations. This work proposes a solution to improve the frequency response of instrument voltage transformers from some hertz up to tens of kilohertz. Mathematical formulation of the technique is presented. Then, the performance of the proposed method is verified with a simulated voltage transformer. Eventually, experimental results relevant to the compensation of a real voltage transformer are shown.

Pasquale Cuccaro, Daniele Gallo, Carmine Landi, Mario Luiso, Gianmarco Romano
RECURSIVE FREQUENCY ESTIMATION TECHNIQUE FOR SYNCHROPHASOR MEASUREMENT APPLICATIONS

The proper and stable operation of a power grid relies on a efficient voltage and current phasor measurement instrumentation. A key feature of such an instrumentation is the accuracy of frequency measurement. The scope of this paper is to present a technique to track frequency variations of voltage and current phasors. We propose a recursive algorithm based on the Maximum Likelihood estimation of the phase; preliminary results show that its performance is comparable to the Cramer-Rao Lower Bound and can track phase variations over time.

Thomas E. Lipe
50-OHM MULTIJUNCTION THERMAL CONVERTERS FOR AC VOLTAGE MEASUREMENTS UP TO 100 MHz

Multijunction thermal converters (MJTCs) are in use as standards for ac voltage measurements at frequencies up to 100 MHz. At the National Institute of Standards and Technology (NIST), MJTCs based on glassy substrates with 50 Ω input impedances are being developed to align more closely with common practice at high frequencies. Preliminary results indicate that 50 Ω MJTCs with excellent properties can be successfully fabricated.

Grzegorz Lentka, Jakub Mróz
IMPEDANCE MEASUREMENT MODULE FOR GAS SENSORS WITH TEMPERATURE CONDITIONING FEATURE

The paper presents an impedance measurement module which is aimed for gas sensor. Sensor’s heater temperature conditioning and modulation feature is available in order to allow implementation of different techniques improving selectivity and sensitivity of gas sensors. The measurement module uses three-parameter sine-fitting technique for impedance measurement. To monitor sensor temperature, the resistance of the sensor’s heater is measured while continuously maintaining temperature control with the aid of PID regulator.

Page 373 of 977 Results 3721 - 3730 of 9762