T.Geetha, V.Jayashankar, V.Jagdeesh Kumar, P.Sankaran
The Southern grid of the Indian power system is a network with an installed capacity of about 37000 MW. It comprises of several thermal and hydel units. The network allows the operating frequency to vary over a band from + 0.5 Hz to -1.0 Hz from the nominal 50 Hz. This is due to the historical chronic shortage of power in the network. Since 2004 about 460 special energy meters with 0.2 class accuracy have been erected across the network. Normally despatch is done every 15 minutes with set point control. On one occasion an experiment involving governor operation across all hydro units and...
Exploring New Frontiers of Instrumentation and Methods for Electrical and Electronic Measurements
· TC4
· 2008
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O. Postolache, H. Geirinhas Ramos, A. Lopes Ribeiro
Conductive specimens such as aluminum plates are tested in order to extract information about possible cracks, flaws and other mechanical damages. Nowadays, eddy current testing (ECT) despite its major benefits (e.g. low cost, high checking speed, robustness and high sensitivity to large classes of defects) implies the utilization of fully coil based architecture probes or hybrid coil-magnetoresistive probes. This work presents an eddy-current testing system based on a giant magnetoresistive sensing device. The application detects and estimates the size of cracks in an aluminum plate...
Exploring New Frontiers of Instrumentation and Methods for Electrical and Electronic Measurements
· TC4
· 2008
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Borikov V.N.
This paper presents both hardware and software of a system for measurement of high-voltage signal with high resolution. The distinctive feature of the system is its application for investigation of the high-voltage plasma processes in solutions which are characterized by the pulse voltage within the range from 100 V to 3 kV and by the pulse duration from a few to hundreds microseconds. The system is portable and consists of the high-voltage dividers, signal level shift unit, oscilloscope, and computer with software. Structure and main principles of operation are described. Its technical and...
Exploring New Frontiers of Instrumentation and Methods for Electrical and Electronic Measurements
· TC4
· 2008
· Download
T.Geetha, V.Jayashankar, V.Jagdeesh Kumar, P.Sankaran
The Indian power system is a large network with an installed capacity of 140 GW. It is unique in that it is the only network which allows the operating frequency to vary over a band from 0.5 Hz to -1.0 Hz from the nominal 50 Hz. The pricing for power purchased is a function of the operating frequency following a commercial mechanism called availability based tariff. Since the network consists of several states which are each commercially independent, an elaborate metering system is required at the interconnecting 400 kV grid. Since 2004, 461 special energy meters with 0.2 class accuracy have...
Exploring New Frontiers of Instrumentation and Methods for Electrical and Electronic Measurements
· TC4
· 2008
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S. Grzelak, M. Zieliński, D. Chaberski
This paper describes the method of analysis of the measuring data obtained from low resolution and non-linear Time Interval Measurements System (TIMS) implemented in to FPGA device. Information about quantization and nonlinearity errors of TIMS warrants more precise analytical results during deterministic jitter investigation. The probability density function of the time-interval fluctuation can be very helpful during diagnosing of the jitter sources. As source of signal with deterministic jitter was used digital Delay Locked Loop (DLL) block, embedded in Virtex-E device. The TIMS with the...
Anna Domańska
The characteristics of actual converters, including sensors, are – to smaller or larger extent – nonlinearity. With respect to the mathematical model describing the characteristics, they can be characteristics with smooth nonlinearity or nonlinearity with discontinuities. The author presented the problem of linearization of the characteristic of converter with nonlinearity with discontinuity that appears in the small value area, i.e. with insensitivity area. In general, this is not an easy task because of the type of nonlinearity and the local character of linearization. A method utilizing...
Danilo Alves de Lima, Guilherme Augusto Silva Pereira, Flávio Henrique de Vasconcelos
Since the beginning of the movement for quality management programs based on ISO 9000 or/and ISO/IEC 17025 that were adopted by many type of industries, calibration laboratories have been under pressure to increase productivity. This work is about a computational system to automate the entire instrument calibration process. The computer vision system proposed is to be used to read the display of both analogue as well as digital instruments that do not have communication interfaces to computers such as GPIB or RS-232. In order to figure out instrument indication, the system employs an optical...
Exploring New Frontiers of Instrumentation and Methods for Electrical and Electronic Measurements
· TC4
· 2008
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Vladimir Haasz, David Slepicka, Petr Suchanek
The performance of current devices is mostly limited by the analogue front-end and analogue-to-digital converter’s (ADC) imperfections. ADC performance is not, as commonly known, ideal. An important parameter is the nonlinearity, which (if it is known) can be corrected in the output data. The performance of three different approximations of ADC nonlinearity (common polynomials, Chebyshev polynomials and Fourier series), the approximations accuracy, and their coefficients’ sensitivity to noise is analyzed in the paper. Also an application of the approximated ADC nonlinearity for its...
Jędrzejewska-Szczerska M., Hypszer R.
Low-coherence interferometric sensors are an important group of optical fibre sensors. Combining high measurement resolution with broad measurement range, these sensors can measure accurately several physical quantities. In this article the authors present the fiber-optic sensors using low-coherence interferometry, which has been designed and elaborated. Being made from dielectric materials, sensors can be used in the presence of electromagnetic fields. Sensors use a new, elaborated by the authors, method of signal processing. The presented results will show that the described technique can...
Exploring New Frontiers of Instrumentation and Methods for Electrical and Electronic Measurements
· TC4
· 2008
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Ariel Dzwonkowski, Leon Swędrowski
Some damages of mechanical parts such as bearings, rotor, shaft or the damages in the elements of electromagnetic system, for example in the wiring of stator, rotor or of the magnetic circuit can appear in induction motors. Statistics say that bearings are this part of induction motors which is most susceptible to damage. That is why the issues connected with diagnostics of bearings are so important. This paper shows diagnostic methods which employ the acceleration of vibration measurements. The appearance of a specific kind of damage in the motor is a source of additional forces whose...
Exploring New Frontiers of Instrumentation and Methods for Electrical and Electronic Measurements
· TC4
· 2008
· Download