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Wyniki wyszukiwania dla: RCD
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Application of RCD and AFDD in low-voltage electrical installations for protection against fire
PublikacjaThe 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.
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Pomiar impedancji pętli zwarciowej w obwodach z RCD i w obwodach zasilanych z UPS
PublikacjaPrzedstawiono główne czynniki wpływające na dokładność pomiaru impedancji pętli zwarciowej w instalacjach niskiego napięcia. Omówiono problemy zbędnego wyzwalania wyłączników różnicowoprądowych podczas tego pomiaru, a także zwrócono uwagę na jego specyfikę w obwodach zasilanych z UPS.
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Time-current tripping characteristics of RCDs for sinusoidal testing current
PublikacjaLow-voltage electrical installations are verified initially – before being put into operation, as well as periodically – during their utilization. According to the IEC standards, the scope of the verification includes measurements of both the tripping current and the disconnection time of residual current devices (RCDs). Experiences in RCDs testing show that disconnection times of two or more similar RCDs can be quite different....
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Tripping of F-type RCDs for High-Frequency Residual Currents
PublikacjaResidual current devices (RCDs) are apparatus commonly used for protection against electric shock in low-voltage electrical installations. They protect people in the case of an earth fault or even in the case of direct contact with the live parts. However, to be effective protective devices, RCDs have to detect residual currents of various waveform shapes which appear in modern electrical installations. For this purpose, RCDs...
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Tripping of F-type RCDs for high-frequency residual currents
PublikacjaResidual current devices (RCDs) are apparatus commonly used for protection against electric shock in low-voltage electrical installations. They protect people in the case of an earth fault or even in the case of direct contact with the live parts. However, to be effective protective devices, RCDs have to detect residual currents of various waveform shapes which appear in modern electrical installations. For this purpose, RCDs are...
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Photosynthesis and sucrose metabolism in leaves of Arabidopsis thaliana aos, ein4 and rcd1 mutants as affected by wounding
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A method of earth fault loop impedance measurement without unwanted tripping of RCDs
PublikacjaIn 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...
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Tripping of F-type RCDs for sinusoidal residual current with superimposed smooth DC component
PublikacjaRecent trends in green energy development make that photovoltaics and electric vehicles are applied on an increasing scale. In both photovoltaic and electric vehicle charging installations, a significant value of DC component of the earth fault current may appear, which is a challenge, in particular, for commonly used residual current devices (RCDs). This paper presents results of the laboratory test on the operation of F-type...
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RCDs Tripping in the Range from DC to AC 50 kHz for Slowly Rising Residual Current
PublikacjaThe wide use of power electronic converters means that in many low-voltage systems earth fault currents containing components from DC to AC of various frequencies have to be taken into account. Due to the tendency to increase the modulation frequency in converters, components of higher frequencies may be in the order of several tens of kilohertz. Therefore, it is very important to verify the behavior of devices for protection against...
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Method of earth fault loop impedance measurement without nuisance tripping of RCDs in 3-phase low-voltage circuits
PublikacjaVerification 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...
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Nowa metoda pomiaru impedancji pętli zwarciowej bez wyzwalania wyłączników różnicowoprądowych
PublikacjaW referacie przedstawiono problematykę pomiaru impedancji pętli zwarciowej w sieciach z wyłącznikami różnicowoprądowymi (RCD - Residul Current Device) oraz zaproponowano nową metodę i układ do pomiaru impedancji pętli bez wyzwalania wyłączników RCD. Nowa metoda umożliwia przeprowadzenie pomiaru przy wykorzystaniu dużej wartości krótkotrwałego całofalowego prądu pomiarowego, co wpływa korzystnie na dokładność pomiaru. Metoda ta...
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Nowe metody pomiaru impedancji pętli zwarciowej dużym pełnofalowym prądem pomiarowym bez wyzwalania wyłączników różnicowoprądowych
PublikacjaWartość impedancji pętli zwarciowej charakteryzuje warunki zwarciowe i napięciowe w sieciach i instalacjach elektroenergetycznych. W artykule przedstawiono problematykę pomiaru impedancji pętli zwarciowej w instalacjach niskiego napięcia z wyłącznikami różnicowoprądowymi (RCD). Zaproponowano nową metodę pomiaru impedancji pętli bez wyzwalania RCD i wykonano dwie odmiany mierników, które ją wykorzystują. Pomiar nową metodą przeprowadza...
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Testing sensitivity of A-type residual current devices to earth fault currents with harmonics
PublikacjaIn 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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Residual current devices in electric vehicles charging installations
PublikacjaThe main requirements of national regulations and international standards regarding protection against electric shock in electric vehicle charging installations are presented. The principles of using residual current devices (RCDs) in such installations are discussed. It is pointed out that RCDs are mandatory equipment for safe charging of electric vehicles. It is noted that the standards require the use of RCDs having an appropriate...
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Analysis of AC/DC/DC Converter Modules for Direct Current Fast-Charging Applications
PublikacjaThe paper is a comprehensive laboratory comparison study of two galvanic isolated solution off-board battery chargers: (1) Si-based cost-effective case, and (2) SiC-bidirectional ready for vehicle to grid concept case. All circuits are modular, and in both cases the DC/DC converter can be replaced according to the end user requirements (the coupled transformer remains the same and is constructed based on 12xC100 cores to avoid...