C. De Capua

Measurement station performance optimization for testing of high efficiency variable speed drives

In efficiency measurement on high performance variable speed drives it is necessary to carry out power measurement on distorted signals with low uncertainty; this involves the adoption of a suitable test stand and an adequate measurement technique. In this paper, a brief description of the implemented measurement station for digital efficiency measurement on high and low power electrical drives is firstly performed. Then, a systematic approach to uncertainty evaluation and a performance optimization criterion are proposed for the automatic measurement station designed for the testing of high efficiency variable speed drives.

Remote Didactic Laboratory “G. Savastano,” The Italian Experience for E-Learning at the Technical Universities in the Field of Electrical and Electronic Measurements: Overview on Didactic Experiments

The Remote Didactic Laboratory Laboratorio Didattico Remoto - LA.DI.RE. ldquoG. Savastanordquo is the e-learning measurement laboratory supported by the Italian Ministry of Education and University. It involves about 20 Italian universities and provides students of electric and electronic measurement courses with access to remote measurement laboratories delivering different didactic activities related to measurement experiments. In order to demonstrate the versatility for didactic use, the overview of some experiments is given. The didactic experiments summarized in this paper concern measurement characterization of instruments and communication systems, measurement devices for remote laboratories, basic electrical measurements, magnetic measurements, electromagnetic-interference measurements, and signal processing for measurement applications.

A Smart THD Meter Performing an Original Uncertainty Evaluation Procedure

In this paper, the authors deal with a smart total harmonic distortion (THD) meter that is able to determine the uncertainty of the measurements that it executes. Such an instrument, which is used for power quality monitoring through the measure of an index, acquires the signal samples from the low-voltage network and evaluates the THD factor. To estimate the uncertainty associated with this last result, a theoretical characterization of the whole instrument realized according to the International Organization for Standardization Guide recommendations (transducer stage included) is discussed first. This approach application has proved to be very useful to justify the necessity of looking for an alternative technique. Therefore, the authors proposed the ldquogrey boxrdquo calibration procedure. Considerations about the comparison of the two procedures have been made.

Power measurements on high distorted signals: experimental comparison between two alternative developed device solutions

The paper deals with a comparison between two original power meters and a high-performance commercial digital wattmeter, for low-uncertainty active power measurements on highly distorted current and voltage waveforms, typical of a variable-speed drive. The comparison is performed in terms of uncertainty via a proper automatic measurement station.

On the Web Service-Based Remote Didactical Laboratory: Further Developments and Improvements

In the paper, the authors report the improvements brought to the remote didactical laboratory, a project to which they have been working for the last two years as presented in P. Daponte et al. (2004). The project has risen from the need to reduce laboratory load, due to the increasing number of undergraduates in Italian University; successively, jointly with the realization of an e-Learning portal for Electric and Electronic Measurement courses, it has represented a way to provide the laboratory experiences to students attending on-line courses. Through the remote laboratory, students are able to execute measurements controlling real instruments, only by means of a common browser. In order to make the laboratory flexible and to grant freedom from software to users, a solution based on Web services, realized in Visual Basic .NET, has been chosen. The recent work has been focuses on the management of connections and queues, for whose aim SQL databases have been involved

A Wireless Measurement System for Estimation of Human Exposure to Vibration During the Use of Handheld Percussion Machines

This paper describes the project of a measurement system for the estimation of the hand-arm exposure to vibration due to percussion machines. The system permits checking the observance of the safety requirements for the worker health during the use of vibrating tools. Pathologies affecting the neurological and vascular systems may be possible consequences due to the frequent exposure to high levels of vibration. The attention is focused on handheld percussion machines. Consequently, the main effects concern syndromes of the bones and muscles of the hand-arm system. Thus, to prevent or reduce possible hazards for health, national laws and international regulations fix maximum tolerable levels for daily vibration exposure. In this view, the authors have projected a measurement system that is able to acquire and process the acceleration levels transmitted to the hand-arm system. The system project has been improved by using radio frequency modules. This way, noises and potential damages to the processing board have been reduced. In fact, wireless communication allows the sensor, which is worn by the workman, to transfer data and available information to a remote DSP unit operating within the covered range. As a result, the vibration affects only the sensing unit. The sensor consists of three accelerometers orthogonally displaced. According to the guidelines of the Standard ISO 5349, the DSP board has the task to remotely process the acquired data by means of embedded algorithms to estimate the daily vibration exposure value. Two memory devices store information on the workman identity and on the metrological characteristics of the measurement system, respectively. When the estimated value of vibration absorption overcomes the safety limits, an acoustic alarm and a warning message on display alert the user to stop the use of the vibrating machine. A Web page keeps track of the vibration exposure history of the worker. Further advances and experimental results concerning the system characterization have allowed the computing algorithms to be optimized. The accuracy and reliability of the systems computation have been improved to reduce possible fault occurrences. The aim of the proposed project is to provide a prevention device for assuring safe working conditions during the exposure to vibration. Therefore, the system assists the exposed workman to avoid the absorption of high levels of vibration according to the regulations.

Measurement uncertainty in evaluating total harmonic distortion factor

In the last years power quality issues have been growing in more and more interest, and therefore the definitions of power quality indices are of increasing concern. Obviously the validity of an index is tightly correlated to its measurement uncertainty. Nevertheless, in the determination of these indexes the evaluation of the measurement uncertainty is often neglected. In the present paper an investigation for the evaluation of the measurement uncertainty is proposed for one of the more used indices: the total harmonic distortion factor (THD). The proposed analysis allows a choice of measurement instrumentation with the purpose to obtain THD measurement inside a band of preset uncertainty.

Metrological performance improvement for power measurements on variable speed drives

Abstract An automatic measurement station for digital efficiency measurement on high and low power variable speed drives has been designed and implemented. An optimization criterion for this measurement station has thus been proposed. This criterion is based upon a systematic approach to uncertainty evaluation, and can be easily extended to any automatic testing equipment. Experimental verification of the proposed methodology has been performed by measurements on actual electrical drives.

A digital measurement technique for EMI tests on variable speed drives

A digital measurement station suitable for conducted interference measurements on the supply line of a Variable Speed Drive (VSD) is presented. This station has been used both for the experimental validation of the emission model of a typical VSD, and for the disturbing characteristics evaluation of the electrical drive. The measurement results have been compared with those coming from the traditional techniques suggested by the Standard Rules.

Remote monitoring of building structural integrity by a smart wireless sensor network

The present paper proposes a wireless sensor network in order to verify the building structural health by monitoring the vibration levels transmitted. In particular the network allows to assess if the vibration levels may cause damage to the building or if it needs further study. The vibration levels are compared with fixed thresholds suggested by studies and regulations. The attention has been focused on the reliability of measurement results and, for this purpose, two algorithms have been implemented. The first takes into account the measurement uncertainty of each sensor network node in order to verify the overcoming of fixed threshold through the use of appropriate decision-making rules. The second algorithm allows to detect possible faulty sensors in order to ensure suitable levels of reliability about the decisions taken on the basis of measurement data, of nearby sensors and of historical calibration information. The common sensor networks used for structural monitoring consist of wired data acquisition system; differently the proposed solution uses the ZigBee technology for wireless communication in order to improve the flexibility and capability of the network.