1,720,963 research outputs found
IEC Std. 61000-3-2 harmonic current emission limits in practical systems: need of considering loading level and attenuation effects
No full textCharacterization of fluctuating harmonics from single-phase power electronics-based equipment
No full textThe present paper is intended to analyze time-varying harmonic absorption of single-phase non-linear loads. To this aim, it is demonstrated that a continuous harmonic monitoring can be of a certain utility, since this practice allows a better characterization of harmonic spectra and an improved understanding of impact due to the various stages of typical operation. Some selected results obtained from a wide monitoring activity performed in a lab are reported in this paper. The results are relevant to NL appliances with power ratings ranging from less than 10?W to several hundred watts, such as desktop PC, printer (both laser and ink-jet), cell phone battery charger, and photocopier. The data thus obtained have been processed in order to determine probability density functions and distribution functions well evidencing the time-varying behavior of harmonic content of the absorbed current. Since a continuous harmonic monitoring allows to follow the nearly instantaneous evolution of the physical quantities (voltage and current) a cross-correlation based analysis of the various harmonic quantities among themselves is more meaningful than the monitoring activities providing longer observation time windows (up to minutes). The results obtained with such calculations can provide good indications for determining the origin of the time-varying behavior as evidenced
Thermal behavior of automatic thermal-magnetic protection circuit-breakers. Experimental test
No full textThe paper reports laboratory tests to evaluate the thermal behavior of thermal-magnetic protection circuit-breakers. They are characterized by a rather variable intervention mode according to the environmental and operating thermal conditions. The scope is verify a relationship between the thermal image of the circuit-breaker and the phenomena that lead the actuator mechanism to tripping. The work shows a various types of temperature sensors and location, highlighting their performance, according to these measurement tests. Thanks to the programmable converters, used for the control of industrial processes, a measurement and data processing system has been implemented integrating directly with PLC Arduino, allowing real-time observation of the measurements. The goal is evaluate the influences of external and environmental temperatures, and on the tripping device mechanism
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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