1,721,195 research outputs found
Uncertainty: Words on the loose [Future Trends in I&M]
No full textDear readers,
The guest author for writing the column of this issue dedicated to young and brilliant engineers is Roberto Tin- arelli. Perhaps no longer so young but surely brilliant! He is Senior Member IEEE and recipient of the 2013 “Outstanding Reviewers” award from the IEEE Instrumentation and Measurement Society. Roberto distinguishes himself not only for his long list of publications but also for his presence in three world patents: a presettable trans- ducer for electrical quantities; a capacitive sensor to sense an electric field generated by a conductor; and an apparatus for sensing the im- pact of a body on a strip located on a support.
I leave you to his nice contribution
A Simple Classification Method for Evaluating Influence Factors Affecting Instrument Transformer Accuracy
No full textUncertainty sources analysis of a calibration system for the accuracy vs. temperature verification of voltage transformers
No full textThe paper deals with the investigation of accuracy vs. temperature variation of inductive instrument transformers. There is still a lack of literature on this specific and nowadays very important topic. In previous works, authors presented results on effects of temperature on voltage instrument transformers accuracy. In this paper the study continues with the uncertainty sources analysis which affects the calibration setup previously proposed. To this purpose, the metrological characterization along with the Monte Carlo method have been applied in order to highlight the main positive features of the calibration setup. Results of such procedures are presented
Effects of Mechanical Pressure on the Tangent Delta of MV Cable Joints
No full textMedium-voltage cable joints are one of the critical components of the distribution networks. They represent the first cause of faults and outages. Among the others, partial discharge, dielectric, and temperature measurements are the typical tests performed for investigating over the early aging of such critical components. In this paper, a new study has been completed correlating the cable joint tangent delta (Tanδ) value to the external pressure applied on the insulating material surrounding the joint. Results confirm the presumed correlation. In fact, an increase of pressure results in a Tanδ decrease, hence in an extension of the cable joint working life
Use of COMTRADE Fault Current Data to Test Inductive Current Transformers
No full textThis paper presents a study on the inductive current transformer behaviour when subjected to distorted actual waveforms. Typical tools adopted to deal with such a condition, as the well-known ratio error, phase error, frequency response, etc. not always provide satisfactory results in all the possible operating condition. In addition, Standards lack in detailing which actual distorted waveforms need to be used to test the transformers. To this purpose, the paper introduces both the use of particular actual fault current waveforms and a simple index for testing the performance of the transformer. Preliminary results show its helpfulness when applied to particular waveforms
A General Easy-to-use Expression for Uncertainty Evaluation in Residual Voltage Measurement
Full text linkThe paper addresses one of the new and most important issues arising when Low Power Voltage Transformers (LPVTs) are used in power network substations for evaluating, among others, the residual voltage measurement. Conversely to open-triangle inductive instrument transformers, the use of phase voltage transformers for measuring the residual voltage gets challenging due to the very high accuracy required for the three LPVTs. In the paper, a general expression to estimate the residual voltage measurement uncertainty, starting from the LPVTs accuracy, is presented. The effectiveness of the proposed approach is then confirmed with both Monte Carlo simulations and actual measurements on a general three-phase system
Temperature-Based Accuracy Estimation on Instrument Transformers via Neural Networks and Microcontrollers
No full textExperimental Validation of Simple Power Quality Indices for Frequency Content Assessment up to 150 kHz
Full text linkThe power system is evolving with the integration of new technologies, including electronic devices and renewable energy sources, which are increasingly used to support new applications, reduce dependence on fossil fuels, and drive system innovation. However, this shift brings a significant drawback: a reduction in power quality (PQ). The literature extensively discusses the impact of poor PQ on electrical assets and explores potential solutions to this new challenge. Building on this foundation, this paper introduces new PQ indices derived from existing metrics and validated on both synthetic and real signals to assess their effectiveness. The aim is to provide researchers and system operators with simple and efficient tools for the clear identification of PQ issues in monitored networks. These new indices are designed to be flexible and independent of acquisition conditions, making them suitable for a wide range of frequencies (e.g., 50 Hz–150 kHz) and applications. After an overview of the PQ landscape, the paper demonstrates the use of these indices on various voltage waveforms, including a case study from a measurement campaign. The promising results indicate that, when combined with existing indices, these new metrics can form a strong foundation for a deeper understanding and more accurate classification of PQ issues in power networks
Performance Evaluation and Comparison of a Low-Cost, PLL-Based Acquisition System under Off-Nominal Conditions
Full text linkIn the last years, strong changes of power network architectures and operation have led to make use of huge quantities of instrumentation, spread around the grid. In fact, there is a strong need to perform very accurate measurements of electrical quantities in many nodes of the network, mainly due to the strong penetration of distributed generation. Recently, also the main Italian utility has asked for such kind of instrumentation. Its main feature must be to perform accurate measurements in all actual conditions. Such conditions include the instrumentation operation during off-nominal condition of the network. To this purpose, in this paper, a low-cost acquisition system developed by the authors, is recalled. Then a full comparison with off-the-shelf products during ideal or not power source is provided. Obtained results highlight the potentialities of the developed system for its implementation in both laboratory or medium/low voltage networks
Implementation and Characterization of a System for the Evaluation of the Starting Instant of Lightning-Induced Transients
No full textVoltage transients are one of the main causes of power quality degradation. There is a search for investigation techniques capable of characterizing and classifying them depending on their origin. A distributed measurement system for Power Quality (PQ) monitoring can be used in parallel with a Lightning Location System (LLS) to assess whether a lightning event is responsible for a voltage transient. This involves the accurate estimate of the transient’s starting instant. In this paper, a system for the measurement of the starting instant of voltage transients is described. It is hosted in each remote unit of a distributed system, built in our Laboratory, for PQ monitoring. The results of the characterization tests are also reported and discussed. They lead to conclude that our system for PQ monitoring can be used in parallel with LLS to assess whether an impulsive voltage transient was induced by lightning
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