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Search results for: GROUND LEAKAGE CURRENT
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Leakage Current Measurements of Surge Arresters
PublicationThe paper presents the methods of assessing the technical condition of varistor surge arresters used in laboratory tests and in operation—performed without disconnecting the arresters from the network. The analysis of the diagnostic methods was supplemented with the results of the measurements of the leakage current of arresters coming directly from their production and used in the power industry. Among the available methods of...
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Immunity of residual current devices to the impulse leakage current in circuits with variable speed drives
PublicationThis paper concerns reliability of supply in variable speed drive circuits with residual current devices. During normal operation of these circuits high value of leakage current causes unwanted tripping of residual current devices. Immunity of residual current devices to the impulse leakage current should be evaluated. The system for testing of residual current devices and results of the test are presented
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Determining the leakage current resistive component by the orthogonal vector method
PublicationThe measurement of the metal – oxide surge arresters (MOSA) leakage current and the analysis of its components is a key diagnostic criterion according to technical standards. During on site MOSA condition assessment, the easy way is based on the measurement only leakage current, without the inconvenient live working measurements of supply voltage. Orthogonal vectors method of determination the resistive leakage current is presented....
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Impact of thermal backfill parameters on current-carrying capacity of power cables installed in the ground
PublicationProper design of power installations with the participation of power cables buried in homogeneous and thermally well-conductive ground does not constitute a major problem. The situation changes when the ground is non-homogeneous and thermally low-conductive. In such a situation, a thermal backfill near the cables is commonly used. The optimization of thermal backfill parameters to achieve the highest possible current-carrying capacity...
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Modeling of a Quasi-Resonant DC Link Inverter Dedicated to Common-Mode Voltage and Ground Current Reduction
PublicationIn this paper, the modeling methodology of the AC drive system with a Parallel Quasi-Resonant DC Link Inverter (PQRDCLI) is described. A presented modeling approach is an attractive tool used for the effective evaluation of a common-mode (CM) voltage and grounds current reduction methods. Designed models of inverter, induction machine (IM), and cable are simple, thus the methods for parameter extraction are not complicated. Verification...
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Electrical signatures of Nimbostratus and Stratus clouds in ground-level vertical atmospheric electric field and current density at mid-latitude station Swider, Poland
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Reducing common mode voltage and bearing currents in quasi - resonant DC - link inverter
PublicationIn the paper, a concept of separation of an inverter-fed induction motor drive from its mains supply by two transistor switches inserted in the dc-link circuit is reexamined based on the proposed parallel quasi-resonant dc-link inverter (PQRDCLI). The objective of the paper is to show an advantage of the proposed topology in limiting high frequency common mode voltage and bearing currents. In the laboratory setup, an induction...
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СИСТЕМА КОНТРОЛЯ СОСТОЯНИЯ ИЗОЛЯЦИИ ЭЛЕКТРОПРИВОДОВ В СЕТЯХ С ГЛУХОЗАЗЕМЛЕННОЙ НЕЙТРАЛЬЮ (System of insulation status monitoring for electric drives in networks with a dead-earth neutral)
PublicationПредложен метод контроля изоляции частотно-регулируемых электроприводов в сетях с глухозаземленной нейтралью. Система контроля изоляции включается в момент остановки электропривода. Ключи инвертора коммутируются по специальному закону, и с помощью сигнала трансформатора тока, который изме- ряет ток во всех трех фазах привода одновременно, определяется ток утечки. Рассмотрена схема датчика тока утечки и приведены экспериментальные...
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Analiza obudowy wykopu dla budynku z kondygnacją podziemną
PublicationW pracy poruszono tematykę analizy obudowy wykopu dla budynku z jedną kondygnacją podziemną, zlokalizowanego w gęstej zabudowie śródmiejskiej. Obliczenia przeprowadzono za pomocą dwóch programów obliczeniowych: GEO5 (moduł: Ściana analiza) i Autodesk Robot Structural Analysis Professional. Całość wyników podsumowano, a wnioski sformułowano w odniesieniu do obecnej sytuacji na rynku budowlanym, charakteryzującej się coraz to trudniejszymi...
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OCENA UZIEMIEŃ SŁUPÓW LINII ELEKTROENERGETYCZNYCH ZWŁASZCZA POSADOWIONYCH NA GRUNTACH O WYSOKIEJ REZYSTYWNOŚCI
PublicationW artykule została omówiona problematyka pomiaru i oceny właściwości uziemień słupów linii elektroenergetycznych z wykorzystaniem przebiegów wolno-i szybkozmiennych. Uzyskanie odpowiednio niskiej wartości rezystancji uziemienia słupa posadowionego na gruncie o rezystywności powyżej 1000Ωm może być trudne. Praca zawiera analizę zmian właściwości statycznych i udarowych uziemień w funkcji rezystywności...