Ioana Odor, Dorin Flaminzeanu, Cornel Baltateanu, Dan Mihai Stefanescu
About the power standards calibration in the National Institute of Metrology, Romania

The paper presents the way in which the Electrical Laboratory from the Romanian Bureau of Legal Metrology – National Institute of Metrology is managing all its capabilities to assure the traceability to SI for the references for electrical power and energy from the utilities and from the manufacturers of watt-hour-meters. The activity described in this paper is performed by using digital equipments, as well as a very accurate analogical power converter, in accordance with the international recognized methods (IEC, IEEE, EA) for calibrating power and energy meters. Till 2006, this activity of calibration was performed only for sinusoidal conditions, following documented procedures and established uncertainty budget under the quality system of the National Institute of Metrology, Romania. So, the laboratory declared the CMCs for AC power single phase and three phases in the Appendix C of The BIPM key comparison database phase. During the last year, for the first time in Romania, new activities are developed for the calibration of power standards and energy meters under non-sinusoidal conditions, and some of them are present in this paper.

Gh. Baluta, V. Horga
Control of Stepper Motors on Virtual Laboratory

E-learning has introduced new opportunities in teaching and learning electrical engineering subjects. This paper presents the architecture of a virtual engineering laboratory, designed to allow remote training in the control of dc, brushless dc and stepper servomotors. An example of stepper servomotor control on virtual laboratory is also presented.

Liliana Mâtiu-Iovan
Improvements to the Algorithm that Uses Divided Differences to Determine the Coefficients in B-Spline Interpolation

In numerical measuring processes the interpolation is an important part. Some algorithms of B-spline interpolation were developed along the time. Here are presented two additional methods to reduce the interpolation errors. These methods could be used in any case for uniformly spaced data. These interpolation processes requires supplementary numerical calculations. Always is to choose between a smallest amount of computation and better results of interpolation.

Salvatore Nuccio, Ciro Spataro, Giovanni Tinè
A procedure to evaluate the electromagnetic immunity degree of a data acquisition system

The paper deals with the empirical evaluation of the electromagnetic immunity degree of PC-based data acquisition systems. A first series of experiments is carried out subjecting the systems to known and standardized disturbances in order to check if and how their performances are corrupted. A second series of experiments is performed in locations where unknown electromagnetic disturbances are present with the aim to find a method for the evaluation of the actual effect of the disturbances. By means of the proposed approach, when a data acquisition system is used to perform a measurement, it is possible to decide if the actual measurement conditions are adequate for the measurement targets. In some cases, moreover, the procedure allows the implementation of algorithms to compensate for the disturbance effects.

Antonio Delle Femine, Carmine Landi, Mario Luiso
A Fully Automated Measuring Station for the Calibration of Voltage Transducers

Power quality analyses in the last years has assumed more and more heaviness in industrial environments, due to the presence of non-linear loads: they require suitable and precise measuring instrumentation. Nevertheless, while there are lots of power quality standards fixing high frequency limits for harmonic analyses, there is a lack of standards concerning transducers calibration at amplitude and frequency different from the rated ones. Therefore in this paper a fully automated measuring station for the calibration of voltage transducers in wide amplitude and frequency ranges is discussed. As an application, the results of the calibration of a commercial transducer are presented: they are used to implement a time-domain procedure for real-time correction of the frequency response of the calibrated transducer.