Search
Filters
total: 4935
-
Catalog
displaying 1000 best results Help
Search results for: LOW-VOLTAGE CIRCUITS
-
Method of earth fault loop impedance measurement without nuisance tripping of RCDs in 3-phase low-voltage circuits
PublicationVerification of electrical safety in low-voltage power systems includes the measurement of earth fault loop impedance. This measurement is performed to verify the effectiveness of protection against indirect contact. The widespread classic methods and meters use a relatively high value of the measuring current (5–20) A, so that they are a source of nuisance tripping of residual current devices (RCDs). The meters dedicated to circuits...
-
Voltage Conditions in Low Voltage Grid with Connected Mictogeneration
PublicationThe introduction of distributed generation into a low voltage grid may cause voltage problems in it. The paper discusses the effect of microgeneration on voltage levels in a low voltage grid. A real low voltage grid of considerable length was selected for the analysis. The grid primarily supplies residential buildings in a rural area. Results of tests that consider potential measures which could be applied in this grid to improve...
-
Low voltage photovoltaic power system
PublicationThe use of photovoltaics is growing rapidly in the industry as well as households. Therefore, educating the public will help them understand solar cell technology, which is becoming more common in everyday life. This paper proposes a demonstrational set-up of photovoltaic panel for the purpose of science education. It was used in numerous outreach activities such as science fairs. Moreover, it proved to be a great tool for education...
-
Improving voltage levels in low-voltage networks with distributed generation – case study
PublicationThe use of distributed generation in low-voltage networks may cause the voltage variation in them, within the wide range. In unfavourable circumstances, the voltage may reach unacceptable values. The paper presents the effect of distributed generation on voltage levels in a selected low-voltage rural distribution network in Poland. An analysis of possible methods for improving voltage levels in this network is conducted. The most...
-
Voltage variations and their reduction in a rural low-voltage network with PV sources of energy
PublicationRenewable sources of energy (RES), especially photovoltaic (PV) micro-sources, are very popular in many countries. This way of clean power production is applied on a wide scale in Poland as well. The Polish legal regulations and tariffs specify that every prosumer in a low-voltage network may feed this network with a power not higher than the maximum declared consumed power. In power networks with RES, the voltage level changes...
-
Multipulse inverter structures with low voltage distortion
PublicationA novel approach to the voltage source inverters (VSI) construction is presented in the paper. The invented inverter structures allow to operate several DC/AC converters in parallel resulting in lower voltage distortions at extremely low switching frequency. The research presented in the paper describes such a parallel operation of the VSI’s which is possible thanks to the use of coupled inductors. The eighteen-pulse three-level...
-
Quality assessment of low voltage surge arresters
PublicationUsers expect reliable operation of the surge arrester during overvoltages, which may originate from a switching process or a lightning discharge. The necessary conditions to guarantee these expectations are: appropriate construction of the surge arrester, its production being maintained in accordance with technical standards, and a positive results of the type test (as well routine and acceptance tests). The recipient, especially...
-
The Phenomena of Bursts by Opening Low-Voltage Relay
Publication -
A High-Efficient Low-Voltage Rectifier for CMOS Technology
PublicationA new configuration of rectifier suiting CMOS technology is presented. The rectifier consists of only two nchannel MOS transistors, two capacitors and two resistors; for this reason it is very favourable in manufacturing in CMOS technology. With these features the rectifier is easy to design and cheap in production. Despite its simplicity, the rectifier has relatively good characteristics, the voltage and power efficiency, and...
-
Low harmonic multipulse voltage converters using coupled reactors
PublicationThis paper presents a novel approach to the multi pulse voltage converters (VC), especially voltage source inverters (VSI) and matrix converters (MC) based on several typical identical modules connected in parallel using coupled reactors. Such arrangements resulting in lower voltage distortions at extremely low switching frequency. The proposed arrangement was validated by simulation. Laboratory models of 18- and 24pulse 3-level...
-
Use of AMI Meters in the Process of Low Voltage Grid Optimization
PublicationThis is a report of a project involving, inter alia, low voltage grid performance optimization with data from AMI meters . The study was supported with a European UPGRID grant, and executed by a consortium of companies from seven European countries, including Poland .
-
Low-Voltage Low-Power Filters with Independent ω0 and Q Tuning for Electronic Cochlea Applications
PublicationAn acoustic second-order low-pass filter is proposed for filter banks emulating the operation of a human cochlea. By using a special filter structure and an innovative quality (Q)-factor tuning technique, an independent change of the cutoff frequency (ω0) and the Q-factor with unchanged gain at low frequencies is achieved in this filter. The techniques applied result in a simple filter design with low Q-factor sensitivity to component...
-
A low-voltage CMOS negative impedance converter for analogue filtering applications
PublicationLow-voltage high-frequency continuous-time filters are still required in many applications and are the subject of continuing research. There are many techniques to realize integrated filters, including OTA C, Opamp RC and MOSFET-C-Opamp. The latter two show high dynamic range at low supply voltage, but their frequency operating range is usually limited to several megahertz. Transconductance filters are dedicated to higher frequencies....
-
Concept of Wireless Low-Voltage DC Socket for the Residential House Application
PublicationThe proposed research is devoted to the comprehensive theoretical and experimental study of the concept of the wireless low power dc socket for residential applications. The main goal of this work is to provide safe dc source for residential customers at power level which is enough in order to supply all typical appliances without power factor correctors. Such types of devices can be already connected to the dc grid and decoupled...
-
Dynamic current-voltage characteristics of dielectrics with extremely low heat conductivity
PublicationZaprezentowano teoretyczny opis metody dynamicznych charakterystyk prądowo-napięciowych w przypadku znacznego gradientu temperatury w ciałach stałych o przewodności jonowej. Otrzymano rozwiązania równania transportu oraz równania charakterystyk, odnoszące się do ruchu cienkiej warstwy nośników ostałej grubości oraz warstwy rozszerzającej się. Podano także przybliżone wyrażenia opisujące czas przelotu nośników. Wyniki zweryfikowano...
-
Output-capacitorless low-dropout regulator using a cascoded flipped voltage follower
PublicationPrzedstawiono udoskonaloną konfigurację wtórnika napięciowego w odwróconej konfiguracji oraz jej zastosowanie w regulatorze o małym spadku napięcia. W pracy przedstawiono teoretyczną analizę podstawowych parametrów wtórnika oraz regulatora napięcia. Ponadto przedstawiono wyniki pomiarów parametrów prototypowego układu scalonego wykonanego z użyciem technologii CMOS 0.35 um. Uzyskane wyniki porównano z rezultatami uzyskanymi w innych...
-
Effect of soil moisture on current-carrying capacity of low-voltage power cables
PublicationOne of the factors affecting current-carrying capacity of underground power cables is the thermal resistivity of soil. Its value in the close proximity of the cable is the most important, and for this reason, in some cases, the local soil is replaced with an another soil type or with a cement-sand mixture. The thermal resistivity of the soil is strongly affected by moisture, and in the case of a cement-sand mixture – as tested...
-
Measurement of the earth fault loop impedance in a low voltage network with operating loads
PublicationW artykule przedstawiono problematykę dokładności pomiaru impedancji pętli zwarciowej w sieciach z obciążeniami roboczymi. Klasyczne metody pomiarowe i mierniki mogą powodować błędy pomiaru przekraczające dopuszczalną wartość. Z tego powodu może wystąpić ryzyko porażenia prądem elektrycznym, ponieważ przy doziemieniu nie będzie spełniony warunek samoczynnego wyłączenia zasilania. Błędy pomiaru w sieci z obciążeniami roboczymi można...
-
Fault loop impedance measurement in low voltage network with residual current devices
PublicationW sieciach i instalacjach niskiego napięcia z wyłącznikami różnicowoprądowymi pomiar impedancji pętli zwarciowej jest kłopotliwy. Prąd pomiarowy powoduje ich zbędne zadziałanie, co uniemożliwia prawidłowe wykonanie pomiaru. W artykule omówiono przyczyny zbędnego zadziałania wyłączników różnicowoprądowych podczas pomiaru impedancji pętli zwarciowej oraz warunki, w jakich ten pomiar można wykonać poprawnie.
-
Application of RCD and AFDD in low-voltage electrical installations for protection against fire
PublicationThe paper presents the principles of application of residual current devices (RCDs) in protection against fire. The permissible rated residual operating current of RCDs is discussed. Limitations in the operation of RCDs in this type of protection are indicated. A new type of a protective device against fire – arc fault detection device (AFDD) – is described.
-
Protection against electric shock in electrical installations with low voltage generating sets
PublicationW referacie przedstawiono zasady ochrony przeciwporażeniowej, zgodne z wymaganiami międzynarodowymi, w sytuacji kiedy instalacja elektryczna jest zasilana z niskonapięciowych zespołów prądotwórczych. Zwrócono uwagę na dobór zabezpieczeń przeciwporażeniowych oraz na wymiarowanie uziemień.
-
Verification of safety in low-voltage power systems without nuisance tripping of residual current devices
PublicationLow-voltage power systems require initial and periodical verification to check the effectiveness of protection against electric shock. As a protection in case of fault, automatic disconnection of supply is most often used. To verify such a protection measure, the earth fault loop impedance or resistance is measured. This measurement is easy to perform in circuits without residual current devices. When residual current devices are...
-
Design of Intelligent Low-Voltage Load Switch for Remote Control System in Smart Grid
PublicationCurrent low-voltage load switches do not support remote disconnect/connect and real-time monitoring of a disconnect/connect state. Addressing to these issues, this paper presents a low-voltage load switch for a smart remote control system, which uses a one-chip microcontroller board and a DC step motor drive mechanism and provides the feedback on the switch status also. Arrears disconnect and full-pay connect control is implemented...
-
Electrical safety in low-voltage DC microgrids with B-type residual current devices
PublicationResidual current devices (RCDs) are most popular devices used in low-voltage installations for protection against electric shock and fire. In cases of high risk of electric shock the application of RCDs is mandatory. Currently, the spread of local direct current (DC) microgrids is widely considered. This creates new challenges for protective systems, in particular those based on RCDs. The main purpose of the research is to test...
-
Random components influence on the values characterising periodic disturbances in low voltage supply lines.
PublicationAnalizowano wpływ składowych losowych na wielkości charakteryzujących zaburzenia okresowe w napięciu zasilania na przykładzie współczynnika zawartości harmonicznych (THD). Zaprezentowano sposób wyznaczania niepewności pomiaru współczynnika THD, uwzględniający występowanie korelacji pomiędzy składową podstawową i kolejnymi harmonicznymi napięcia sieci a także między poszczególnymi harmonicznymi. Przedstawiono analizę wyników z pomiarów...
-
Low-Voltage LDO Regulator Based on Native MOS Transistor with Improved PSR and Fast Response
PublicationIn this paper, a low-voltage low-dropout analog regulator (ALDO) based on a native n-channel MOS transistor is proposed. Application of the native transistor with the threshold voltage close to zero allows elimination of the charge pump in low-voltage regulators using the pass element in a common drain configuration. Such a native pass transistor configuration allows simplification of regulator design and improved performance,...
-
A new method of fault loop resistance measurement in low voltage systems with residual current devices
PublicationThis paper presents a new method of fault loop resistance measurement in low voltage systems with residual current devices. The method enables measuring fault loop resistance without nuisance tripping of residual current devices, by application an unconventional waveform of measurement current. It is important for proper verification of the effectiveness of protection against electric shock.
-
Experimental verification of a new method of loop resistance testing in low voltage systems with residual current devices
PublicationA periodical verification of the effectiveness of protection against electric shock shall be performed in low voltage systems. The scope of this verification includes loop impedance/resistance testing. If a residual current device is installed in a tested circuit, this testing is problematic. A residual current device trips out during the test, because of the high value of measurement current. This precludes the execution of the...
-
Efficient Analysis of Noise Induced in Low-Voltage Installations Placed Inside Buildings with Lightning Protection Systems
PublicationThis paper describes an efficient approach to the broadband analysis of lightning protection systems (LPSs) using the method of moments (MoM) implemented in the frequency domain. The adaptive frequency sampling (AFS) algorithm, based on a rational interpolation of the relevant observable (e.g., voltage, current, electric or magnetic field) which describes the properties of the LPS, is employed to reduce the number of samples computed...
-
Closed-Loop Control System Design for Wireless Charging of Low-Voltage EV Batteries with Time-Delay Constraints
PublicationThis paper presents an inductive power transfer system on the basis of a double single- phase three-level T-type inverter and two split transmitting coils for constant current and constant voltage wireless charging of low-voltage light electric vehicle batteries with closed-loop control, considering time-delay communication constraints. An optimal control structure and a modified control strategy were chosen and implemented to...
-
Closed-Loop Control System Design for Wireless Charging of Low-Voltage EV Batteries with Time-Delay Constraints
Publication -
The Method of Multi-criteria Analysis to Support the Decision on Load or Micro-generation Connection to a Low- or Medium-voltage Power Grid
PublicationThis paper presents a method that supports the decision in terms on selecting the best option of a load connection to a low- or medium-voltage power distribution grid, and of a micro-generation source connection to a low-voltage grid. The method is based on the search for the option with the lowest aggregate assessment measure, which is the weighted average of partial assessment measures determined for each of eight considered...
-
Hybrid stepless distribution transformer with four-quadrant AC/DC/AC converter at low voltage side - simulation tests
PublicationThe article presents the work of the stepless hybrid distribution transformer (HT), as an alternative to the so far applied Automatic Voltage Regulator (AVR) solutions, used to control the voltage in the power system in terms of the fundamental harmonic. The HT is a combination of a conventional distribution transformer and an AC/DC/AC converter connected in series with the transformers secondary winding. In the work the basic...
-
The scanning electron microscopy (SEM) studies of low voltage copper cables
Open Research DataThe dataset contains the scanning electron microscopy (SEM) images of the low voltage copper cables, which were studied in the article discussing the regulatory requirements for checking the electrical resistance of such cables. The cables were cut and studies in cross-section. The full results were published in:
-
System of protection against electric shock for circuits with power electronics converters
PublicationModern low voltage circuits are very often equipped with power electronics converters, therefore in these circuits non-sinusoidal earth currents (touch currents) may occur. For non-sinusoidal currents safety criteria should be modified. This paper presents these modified criteria and a computer system of protection against electric shock which can be implemented in circuits with power electronics converters. The system is based...
-
Selected problems of earth fault loop impedance testing in circuits fed from UPS
PublicationIn the paper a principle of earth fault loop impedance testing in low voltage systems has been presented. Selected factors, influencing accuracy of the testing, are indicated. A structure of UPS of VFI-type and the problem of impedance testing in circuits with such type of UPS are discussed.
-
Effect of the let-through energy of overcurrent protective devices on the temperature of conductors during short-circuits
PublicationThe scope of the verification of low-voltage systems covers the earth fault loop impedance measurement. This measurement is usually performed with the use of low-value current meters, which force a current many times lower than the one occurring during a real short-circuit. Therefore, the international standard recommends consideration of the increase of resistance of conductors with the increase of temperature, which may occur...
-
Ladder-Based Synthesis and Design of Low-Frequency Buffer-Based CMOS Filters
PublicationBuffer-based CMOS filters are maximally simplified circuits containing as few transistors as possible. Their applications, among others, include nano to micro watt biomedical sensors that process physiological signals of frequencies from 0.01 Hz to about 3 kHz. The order of a buffer-based filter is not greater than two. Hence, to obtain higher-order filters, a cascade of second-order filters is constructed. In this paper, a more...
-
Computer System for Evaluation of Shock Hazard in Circuits with Non-sinusoidal Earth Currents
PublicationEffects of current on people are mainly considered for 50/60 Hz sinusoidal current and smooth direct current. However, modern low voltage circuits are very often equipped with power electronics converters – rectifiers, frequency converters, therefore non-sinusoidal earth currents (touch currents) occur. For non-sinusoidal currents safety criteria should be modified. This paper presents a computer system, based on LabVIEW environment,...
-
Evaluation of applicability of classic methods of a fault loop impedance measurement to circuits with residual current devices
PublicationMeasurement of fault loop impedance in low voltage grids and systems is in most cases performed to verify the effectiveness of protection against electric shock by automatic disconnection of supply. For the sake of measurement accuracy, it is advisable to perform it using large current. Unfortunately, in circuits with residual current devices which are very widely used nowadays, a large measurement current may trigger those devices...
-
Low-frequency tripping characteristics of residual current devices
PublicationFast development of various types of converters makes their utilization in industry and in domestic installations very common. Due to converters, an earth fault current waveform in modern circuits can be distorted or its frequency can be different than 50/60 Hz. Frequency of earth fault (residual) current influences tripping of residual current devices which are widely used in low voltage systems. This paper presents the behaviour...
-
A method of earth fault loop impedance measurement without unwanted tripping of RCDs
PublicationIn low-voltage networks, earth fault loop impedance (EFLI) measurement is the basis for assessing the effectiveness of automatic disconnection of supply. Such a measurement is performed during initial and periodical verification, especially in a TN low-voltage network. Nowadays, due to widespread application of residual current devices (RCDs), such test is difficult in many circuits because RCDs operate during the test. In this...
-
Residual current protective device for circuits of distorted earth fault currents – concept, construction and testing
PublicationThis dissertation presents behavioral and performance verification and analysis of residual current devices (RCDs), as well as a proposal for the construction of a new RCD protection. The state of the art focuses over pre-existing design of the RCD and its behavior and response to the circuits with distorted (non-sinusoidal) earth fault currents. The study highlights the loopholes of the existing design and depicts the problem...
-
Grzegorz Lentka dr hab. inż.
PeopleGrzegorz Lentka obtained his MSc title in electronics, specialization Measurement Systems at Gdańsk University of Technology, Faculty of Electronics, Telecommunications and Informatics in 1996. He obtained the PhD title in 2003 and habilitation in 2014, respectively. Currently he is an professor in Department of Metrology and Optoelectronics. His main scientific interests are focused on digital signal processing for metrology,...
-
A current-controlled FET
PublicationA novel semiconductor device, viz., Horizontally-Split-Drain Current-Controlled Field-Effect Transistor (HSDCCFET) with two control electrodes is proposed in this works. For the sake of brevity, the device can be called a CCFET. Operating principle of the proposed transistor is based on one of the galvanomagnetic phenomena, the Biot-Savart-Laplace law and a Gradual Channel Detachment Effect (GCDE). The transistor is dedicated...
-
Justyna Signerska-Rynkowska dr inż.
PeopleI am currently an assistant professor (adjunct) at Gdansk University of Technology (Department of Differential Equations and Mathematics Applications). My scientific interests include dynamical systems theory, chaos theory and their applications to modeling of biological phenomena, especially to neurosciences. In June 2013 I completed PhD in Mathematics at the Institute of Mathematics of Polish Academy of Sciences (IMPAN) (thesis...
-
Safety issues referred to induced sheath voltages in high-voltage power cables – case study
PublicationLoad currents and short-circuit currents in high-voltage power cable lines are sources of the induced voltages in the power cables’ concentric metallic sheaths. When power cables operate with single-point bonding, which is the simplest bonding arrangement, these induced voltages may introduce an electric shock hazard or may lead to damage of the cables’ outer non-metallic sheaths at the unearthed end of the power cable line. To...
-
Przekształtnik prądu jako sterownik w układach napędowych z silnikami indukcyjnymi
PublicationThe circuits used for power conversion applied in drives with electric machines are classified into two groups: voltage source inverters (VSI) and current source inverters (CSI). Application of the current source inverter results in better properties of drive than application of voltage source inverter because there is no output filter. The development of power electronics and especially the IGBTs, in which on/off-times are very...
-
Application of infrared thermoography to non-contact testing of varistors
PublicationTesting of varistors using thermography was carried out in order to assess their protective properties against possible overvoltage phenomena in the form of high-level voltage surges. An advantage of the thermography technique is non-contact temperature measurement. It was proposed to assess the properties of varistors workingin electronic devices as protective elements, on the basis of estimating temperature increments on varist...
-
Stanisław Galla dr inż.
PeopleStanisław Galla was born in 1970 in Gdańsk. He graduated from the Secondary Technical School of Mechanical and Electrical Engineering in Gdansk (1990). He studied at the Faculty of Electrical Engineering at Gdansk University of Technology (graduated in 1996). His PhD thesis entitled "Methodology for increasing the accuracy of low frequency measurements of periodic disturbance indicators in low voltage networks" was defended in...