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Search results for: current-carrying capacity
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The Influence of Limiters UEL and OEL (The power angle, stator's current and excitation current) ot the possibility of voltage collapse development
PublicationVoltage stability has been a major concern for power system utilities because of event of voltage collapses in the recent past. Sometimes, power system events have shown the need for generators to operate in the overexcited and underexcited region to support stable operation. Modern excitation systems include devices for controlling or limiting machine terminal voltage (overvoltage limiters), volts per hertz ratio (V/Hz limiters),...
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Remote current measurement with FPGA digital processing
PublicationThe work presents an implementation of a modular measurement and control systemthat controls variants of mains supply of 230V electrical equipment. The system allowsto supervise power consumption in the office electronic equipment. The system detectsthe instant of the reduced power consumption by a device and makes possible itsswitch-off in order to reduce energy cost. The current is measured with integratedcurrent/voltage converters....
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Yerba Mate - A Long but Current History
PublicationBearing in mind the growing interest in Yerba Mate, a comprehensive study has been prepared containing the most important aspects and possibilities of its use. The introduction of the work contains the species characteristics of Yerba Mate, as well as information about the origin and places of cultivation. The next part focuses on the analysis of the composition, pointing to purine alkaloids, polyphenols, saponins, and minerals...
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Improving sensitivity of residual current transformers to high frequency earth fault currents
PublicationFor protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed...
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Measurements of radiation emission of a portable power bank with a capacity of 10400 mAh
Open Research DataThe dataset contains the emission measurement results that are part of comprehensive tests carried out for portable power banks with different capacities. The measurements were performed in the frequency range from 30 MHz to 3 GHz using a Gigahertz Transverse Electromagnetic (GTEM) cell (Fig. 1). The test setup was configured to measure a portable power...
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Predicting the seismic collapse capacity of adjacent SMRFs retrofitted with fluid viscous dampers in pounding condition
PublicationSevere damages of adjacent structures due to structural pounding during earthquakes have emphasized the need to use some seismic retrofit strategy to enhance the structural performance. The purpose of this paper is to study the influence of using linear and nonlinear Fluid Viscous Dampers (FVDs) on the seismic collapse capacities of adjacent structures prone to pounding and proposing modification factors to modify the median...
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Current advances in membrane processing of wines: A comprehensive review
PublicationBackground Membrane-based operations, especially pressure-driven membrane operations, are today well-established procedures for various applications in the wine industry thanks to their intrinsic properties and undoubted advantages over traditional methods. Emerging membrane processes, such as pervaporation, electrodialysis and osmotic distillation, forward osmosis, membrane contactors, offer new and interesting perspectives to...
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Subadditivity of the minimum output entropy and superactivation of the classical capacity of quantum multiple access channels
PublicationWe study subadditivity of the minimum output entropy (Hmin) of quantum multiple access channels (MACs). We provide an example of violation of the additivity theorem for Hmin known in classical information theory. Our result is based on a fundamental property of MACs, i.e., independence of each sender. The channels used in the example can be constructed explicitly. On the basis of subadditivity of Hmin we also provide an example...
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Sylwester Kaczmarek dr hab. inż.
PeopleSylwester Kaczmarek received his M.Sc in electronics engineering, Ph.D. and D.Sc. in switching and teletraffic science from the Gdansk University of Technology, Gdansk, Poland, in 1972, 1981 and 1994, respectively. His research interests include: IP QoS and GMPLS and SDN networks, switching, QoS routing, teletraffic, multimedia services and quality of services. Currently, his research is focused on developing and applicability...
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Occurrence of antimicrobial resistant bacteria in environment and the statistical analysis of this phenomenon
PublicationIntroduction: In this study the occurrence of antimicrobial resistance patterns among fecal indicators (Escherichia coli and Enterococcus spp.) was analyzed in water and wastewater samples. The trends in antimicrobial resistance were analyzed using basic statistical methods. Methods: Samples were obtained from two local watercourses (Oliwski Stream and Reda River) as well as from the wastewater treatment plant (WWTP) Gdansk - Wschod....
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The Use of Cluster Analysis to Assess the Wear Resistance of Cermet Coatings Sprayed by High Velocity Oxy-Fuel on Magnesium Alloy Substrate
PublicationCermet coatings are one of the best surface protection of machine elements against wear. On the other hand, the most universal and economically justified method of applying such coatings is high velocity oxy-fuel (HVOF) spraying. This method makes it possible to produce coatings characterized by compact structure, low porosity and very good adhesion to the substrate. All these fundamental properties contribute to the high wear...
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Reduction of exceeding the guaranteed service time for external trucks at the DCT Gdańsk container terminal using a six sigma framework
PublicationPurpose The purpose of this research was to investigate ways to reduce the average amount of exceeded guaranteed service time for external trucks at Deepwater Container Terminal Gdańsk Sp z o.o. (DCT Gdańsk) via dosing the gate activities, in particular IN-Gate entry process of trucks carrying import/export/transit containers. Design/methodology/approach A Six Sigma methodology with the DMAIC methods along with the SIPOC chart,...
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Effect of kenaf fibre modification on morphology and mechanical properties of thermoplastic polyurethane materials
PublicationThe presented study examined the morphology and mechanical properties of biocomposites obtained from kenaf natural fibre and thermoplastic polyurethane. Kenaf was modified using various methods, namely: acetylation, blocked isocyanate, maleic anhydride and permanganate treatment. Those methods and ways of carrying out of surface modifications were not studied before on kenaf/thermoplastic polyurethane composites. Different fibre...
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Novel application of terminal restriction fragments length polymorphism method (t-RFLP) for identification of six clinically important Candida sp.
PublicationTerminal restriction fragments length polymorphism method (t-RFLP) is a modified classical RFLP method. The main difference is based on carrying out PCR using a fluorescently labeled primer or primers. The result of such modification is that after digestion of amplicons only terminal fragments of PCR product (containing fluorescent dye) are visualized. T-RFLP method has found application in environmental microbiology and epidemiology....
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Effect of presence of lifting pocket on the THD performance of a large tilting-pad thrust bearing
PublicationHydrostatic assistance is a commonly used method to improve limited load carrying ability of tiltingpad thrust bearings during transient states of operation of vertical shaft hydro-generators. Despite of special hydraulic equipment (as pumps, valves, etc.), it also requires manufacturing of special recesses/pockets at pad sliding surfaces, into which oil is injected under high pressure. It allows to lift the rotor before start-up...
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Refurbishment of a historical building - design issues
PublicationOver a 10-year modernization of the main building of Gdansk University of Technology is coming to the end. The ever increasing number of students requires not only the development of the campus with new facility buildings, also the existing buildings are subject to adaptation and modernization. In addition to high-impact solutions, as restoring the former glory of the building (reconstruction of the clock tower), or introducing...
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Large hydrodynamic thrust bearing: Comparison of the calculations and measurements
PublicationHydrodynamic thrust bearings, used to carry axial loads in heavily loaded shafts of water power plants hydro turbines, can reach outer diameters even exceeding 5 m. In such large objects scale effect could be observed. According to this, allowable bearing specific load assuring safe operation of the bearings has to be decreased, which increases thrust bearing dimensions. This effect is caused by excessive thermal deflections of...
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Reliable data-driven modeling of high-frequency structures by means of nested kriging with enhanced design of experiments
PublicationData-driven (or approximation) surrogate models have been gaining popularity in many areas of engineering and science, including high-frequency electronics. They are attractive as a way of alleviating the difficulties pertinent to high computational cost of evaluating full-wave electromagnetic (EM) simulation models of microwave, antenna, and integrated photonic components and devices. Carrying out design tasks that involve massive...
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Linear revitalization - problems and challenges. Discursive article
PublicationThe aim of the article, defined by the author as discursive, is to give the answer as to whether within ‘revitalization’ we should distinguish the notion of ‘linear revitalization’ – not yet defined in Polish and English-language literature. The author presents the thesis that we should do so by presenting the idea, its specific character and its role. This kind of action seems to have, in the author’s opinion, a positive influence...
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How to enhance perception of reassembled but incomplete works of ancient art? Eye-tracking study of virtual anastylosis.
Publicationn 1964 the Venice Charter described anastylosis as the only acceptable method of reassembly of architectural remains. Although the scientific community has agreed with the Charter’s decision, many questions pertaining to the technical and aesthetic aspects of anastylosis remain unanswered. Virtual anastylosis seems one of the most promising digital solutions to finding at least some answers, as it permits testing various solutions...
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A review of design approaches for the implementation of low-frequency noise measurement systems
PublicationElectronic noise has its roots in the fundamental physical interactions between matter and charged particles, carrying information about the phenomena that occur at the microscopic level. Therefore, Low-Frequency Noise Measurements (LFNM) are a well-established technique for the characterization of electron devices and materials and, compared to other techniques, they offer the advantage of being non-destructive and of providing...
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The Use of USV to Develop Navigational and Bathymetric Charts of Yacht Ports on the Example of National Sailing Centre in Gdańsk
PublicationApart from extensive infrastructure protection, modern yacht ports should primarily provide vessels with navigational safety associated with their maneuvering on the approach fairway, as well as mooring in the port aquatory. For this reason, yachts entering the harbor should have up-to-date, accurate, and reliable charts of the port and its surroundings. This article presents hydrographic surveys conducted in the National Sailing...
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Rigorous numerics for critical orbits in the quadratic family
PublicationWe develop algorithms and techniques to compute rigorous bounds for finite pieces of orbits of the critical points, for intervals of parameter values, in the quadratic family of one-dimensional maps fa(x)=a−x2. We illustrate the effectiveness of our approach by constructing a dynamically defined partition P of the parameter interval Ω=[1.4,2] into almost 4 million subintervals, for each of which we compute to high precision the...
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Equivalent standard manoeuvres for pod-driven ships
PublicationProcedures for carrying out the manoeuvring tests presented in International Maritime Organisation (IMO) resolution MSC.137(76) are based on the capabilities of ships with conventional steering-propulsion systems. Therefore they do not correspond to ships with other steering-propulsion devices, like pod drives. IMO is aware of this shortcoming and for ships with non-conventional steering and propulsion system may permit the use...
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Development of Intelligent Road Signs with V2X Interface for Adaptive Traffic Controlling
PublicationThe objective of this paper is to present a practical project of intelligent road signs, under which a series of new products for the regulation of traffic is being created. The engineering part of the project, described in this paper, was preceded by a series of experimental studies, the results of which were described in another paper accepted for publication at the MTS-ITS conference 2019, entitled "Comparative study on the effectiveness...
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Predicting the seismic collapse capacity of adjacent SMRFs retrofitted with fluid viscous dampers in pounding condition
PublicationSevere damages of adjacent structures due to structural pounding during earthquakes have emphasized the need to use some seismic retrofit strategy to enhance the structural performance. The purpose of this paper is to study the influence of using linear and nonlinear Fluid Viscous Dampers (FVDs) on the seismic collapse capacities of adjacent structures prone to pounding and proposing modification factors to modify the median...
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Mathematical model defining volumetric losses of hydraulic oil compression in a variable capacity displacement pump
PublicationThe objective of the work is to develop the capability of evaluating the volumetric losses of hydraulic oil compression in the working chambers of high pressure variable capacity displacement pump. Volumetric losses of oil compression must be determined as functions of the same parameters, which the volumetric losses due to leakage, resulting from the quality of design solution of the pump, are evaluated as dependent on and also...
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Downlink Capacity-Coverage Trade-off Estimation Based on Measurement of WCDMA/FDD Interface Load
PublicationThe method of capacity-coverage trade-off determination by using of universal load characteristics and normalized coverage curves for the WCDMA/FDD radio interface has been presented. The practical applications of discussed method for UMTS radio network planning process and network exploitation has been mentioned.
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Requirements for Residual Current Devices Intended for Electric Vehicle Charging Systems
PublicationThe properties of residual current devices have been presented from the point of view of their ability to detect a specific shape of the residual current waveform. Moreover, the standard requirements relating to residual current protection used in electric vehicle charging installations have been pointed out. The operating characteristics of the IC-CPD and RDC-DD protections, which are intended for charging electric vehicles in...
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Tax system in Poland - current situation and direction of changes
Open Research DataThe study conducted on a group of 259 entrepreneurs from various regions of Poland concerns the opinions of business owners on the current tax situation, as well as potential changes in the tax system.
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Current Challenges in Targeting Tumor Desmoplasia to Improve the Efficacy of Immunotherapy
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The effect of earth fault current harmonics on tripping of residual current devices
PublicationSzerokie zastosowanie przekształtników, a w szczególności przemienników częstotliwości sprawia, że wyłączniki różnicowoprądowe znajdują się w obwodach, w których może płynąć odkształcony prąd ziemnozwarciowy. Prąd ziemnozwarciowy w obwodach z przemiennikami częstotliwości zawiera harmoniczne, których rząd głównie zależy od częstotliwości PWM. Odkształcony prąd wpływa na poprawne wyzwalanie wyłączników różnicowoprądowych. W artykule...
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Current status and future success of renewable energy in Pakistan
PublicationMismatch between energy demand and supply from last two decades has been increasing because of the domination of expensive imported oil in energy mix of Pakistan. To import crude oil Government paid US $ 9 billion in 2008–2009 to meet the energy demands...
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Modelling of Diffusing Capacity Measurement Results in Lung Microangiopathy Patients. A novel Diagnostic Suppport
PublicationLung microangiopathy is a little known negative influence of diabetes mellitus on the functioning of the lungs. The aim of this study is to design a supportive method for diagnosing lung microangiopathy. This will be based on routinely performed pulmonary measurements as well as on investigation process modelling and data processing. A model of the diffusion of oxygen from the alveoli to the blood has been described with a set...
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Visual Capacity Assessment of the Open Landscape in Terms of Protection and Shaping: Case Study of a Village in Poland
PublicationThis article describes the methodology and results of research on landscape visual capacity. The aim of the project was to develop a tool that would support planning and design decisions at the level of communal management in rural areas in Poland through systematic application of visual criteria. Their importance in the protection, management and shaping of space is underlined by the document produced at the European Landscape...
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Compensation of supply current harmonics, reactive power, and unbalanced load current balance in the closed-loop control of a shunt active power filter
PublicationThis paper presents the compensation tasks performed by a shunt active power filter, including compensation of harmonic currents, reactive power, and an unbalanced load current. The paper demonstrates novel control of the shunt active power filter in a closed-loop system. The control algorithm was verified by performing simulations and compared the simulated results with those obtained in an open-loop control system. All simulations...
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Prediction of pile shaft capacity in tension based on some direct CPT methods – Vistula Marshland test site
PublicationThis paper presents different CPT methodologies for the prediction of the pile shaft resistance in tension on the example of three reference screw piles of the Jazowa test site in Poland. The shaft capacity was estimated based on the cone resistance, sleeve friction and CPT excess pore water pressure. Three piles with a diameter of 0.4 m and the length...
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Measurements of radiation emission of a portable power bank with a capacity of 2600 mAh
Open Research DataThe dataset contains the emission measurement results that are part of comprehensive tests carried out for portable power banks with different capacities. The measurements were performed in the frequency range from 30 MHz to 3 GHz using a Gigahertz Transverse Electromagnetic (GTEM) cell. The test setup was configured to measure a portable power bank...
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Behavior of residual current devices at frequencies up to 50 kHz
PublicationThe use of residual current devices (RCDs) is obligatory in many types of low-voltage circuits. They are devices that ensure protection against electric shock in the case of indirect contact and may ensure additional protection in the case of direct contact. For the latter purpose of protection, only RCDs of a rated residual operating current not exceeding 30 mA are suitable. Unfortunately, modem current-using equipment supplied...
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Automated Diagnostics of Current Pick-Up Disturbances in Electric Traction Networks
PublicationThe present work defines the basic causes of bow disturbances of current pick-up, sets a task of establishing a system of automated control of bow disturbances at feeder zones of electric traction networks, proposes structural variants of the technical system implementation, describes the algorithm of detection of bow disturbances of current pick-up.
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Effect of Soft Handover on the Capacity of WCMDA/FDD Interfece Using MRC RAKE Receiver in Uplink
PublicationIn the paper the mechanism of soft and hard hanover in UMTS is presented. Simulation tests for different services having various performance requirements and transmission rates have beeen made. Simulation results showing effect of soft handover in comparison with hard handover on the capacity of WCMDA/FDD radio interfaceare described, when the RAKE receiver with Maximal Ratio Combining has been implemented in RNC.
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Stability and load bearing capacity of a braced truss under upward wind loading
PublicationThe paper is focused on the numerical and experimental investigation of stability of a steel truss under upward wind loading. The structure was stiffened by elastic braces situated at the top and bottom chord. Usually the lateral (translational) brace stiffness is considered. However, the rotational stiffness of braces caused by interaction between torsional stiffness of the truss top chord and bending stiffness of the roof elements...
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Stability and load bearing capacity of a braced truss under upward wind loading
PublicationThe paper is focused on the numerical and experimental investigation of stability of a steel truss under upward wind loading. The structure was stiffened by elastic braces situated at the top and bottom chord. Usually the lateral (translational) brace stiffness is considered. However, the rotational stiffness of braces caused by interaction between torsional stiffness of the truss top chord and bending stiffness of the roof elements...
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Behavior of residual current devices at earth fault currents with DC component
PublicationLow-voltage electrical installations are increasingly saturated with power electronic converters. Due to very high popularity of photovoltaic (PV) installations and the spread of electric vehicles (EV) as well as their charging installations, DC–AC and AC–DC converters are often found in power systems. The transformerless coupling of AC and DC systems via power electronic converters means that an electrical installation containing...
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Modification of the structural model of manipulator's carrying system for a use of modal control at energy performance index.
PublicationW pracy rozważa się drgania niestacjonarnego układu nośnego manipulatora IRb-6 modelowanego dyskretnie metodą sztywnych elementów skończonych. Z uwagi na gwałtowne ruchy (start, zatrzymanie) poszczególnych członów manipulatora, jest to problem o dużym znaczeniu praktycznym. Jednym ze sposobów nadzorowania tych drgań jest wykorzystanie sterowania modalnego przy energetycznym wskaźniku jakości. Uwzględnia on zmianę w czasie względem...
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Method of sacrificial anode dual transistor-driving in stray current field
PublicationIn order to control a magnesium anode in a stray current interference field, a dual transistor driving system has been proposed. It consisted of a combination of PNP and NPN transistors. Dual transistor driven system and direct anode to cathode connection were electrochemically tested in 3% NaCl solution. The dual transistor driven system increased the anode efficiency and reduced hydrogen evolution and the risk of embrittlement....
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Testing sensitivity of A-type residual current devices to earth fault currents with harmonics
PublicationIn many applications, modern current-using equipment utilizes power electronic converters to control the consumed power and to adjust the motor speed. Such equipment is used both in industrial and domestic installations. A characteristic feature of the converters is producing distorted earth fault currents, which contain a wide spectrum of harmonics, including high-order harmonics. Nowadays, protection against electric shock in...
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Comprehensive compensation of grid current distortion by shunt active power filters
PublicationThe paper presents a comprehensive approach to the compensation of grid current distortion in shunt active power filter systems. Four sources of current distortion are addressed: imperfect grid synchronization caused by the distortion in the grid voltages, time delays in the evaluation of grid voltages and computation of compensating currents, fluctuations of the dc bus voltage, and the distortion of inverter output voltages due...
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Time-current tripping curves of arc fault detection devices
PublicationTripping curves of arc fault detection devices, in accordance with PN-EN 62606 “General requirements for arc fault detection devices” have been presented in the paper. Consequently the most fundamental differences in arc fault detection devices tripping compared to circuit-breakers and residual current devices have been indicated.
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Comparison of residual current devices tripping characteristics for selected residual current waveforms
PublicationZgodnie z normami międzynarodowymi, w instalacjach o zwiększonym ryzyku porażenia prądem elektrycznym należy stosować wyłączniki różnicowoprądowe wysokoczułe. Dla zapewnienia skutecznej ochrony przeciwporażeniowej zainstalowany wyłącznik różnicowoprądowy powinien prawidłowo wykrywać określony kształt prądu różnicowego. W artykule przedstawiono charakterystyki działania wyłączników różnicowoprądowych przy wybranych przebiegach odkształconego...