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Wyniki wyszukiwania dla: CABLE LINE
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Energy losses reduction in the medium voltage cable line – case study
PublikacjaThe paper presents an analysis of energy losses in a power cable system, which is composed of two 30 kV cable lines. This cable system is located at the seaside holiday area, so the load profile during a year is specific. Energy losses related to reactive power transmission, as well as to currents induced in the sheaths of the cables, are subject to analysis. Measurements were made in the system in order to prepare a computer model...
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Modelling of MV and HV Cable Lines
PublikacjaOverhead and cable lines are fundamental elements of power systems. Participation of cable lines is smaller and their percentage decreases as voltage is increased. HV cable lines are often built with the use of cables which are composed of coaxial metallic sheaths. Such cables are also often used in MV networks. The sheath may operate in different confgurations. In the case of Polish MV network the sheaths are earthed at both ends....
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Overheating of underground power cable line due to its partial exposition to solar radiation
PublikacjaCurrent-carrying capacity of underground power cable lines depends, among others, on thermal resistivity of the soil and cables layout: trefoil formation, flat formation with or without spacing. If conditions for heat transfer in the ground are favorable, the current-carrying capacity is relatively high. Therefore, it generates risk of the power cables overheating, if part of the cable line is located vertically in the air, to...
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Incomplete Cross-Bonding in the MV Line. Experience from the Operation of MV Single Cable Lines
PublikacjaCable lines are one of the basic components of power systems. Medium and high voltage cables mainly comprise a metallic sheath, which is concentric to the main core conductor. There are several operating schemes of such cable lines, which differ in the place of earthing of sheaths and the possible use of the sheaths and/or conductors crossing. The sheaths cross-bonding is typically done in two places of one cable line section,...
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A new approach to cross-bonding in medium voltage cable lines
PublikacjaThe medium voltage underground cable sheaths are usually bonded and earthed in every substation on the cable route. This results in additional power losses in the sheaths. The paper presents an idea of reducing power losses caused by sheaths cross-bonding. The idea of sheaths cross-connecting only in selected MV/LV substations is given instead of a typical solution, where sheaths cross-bonding requires installing additional joints...
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Cross-Bonding of MV Cable Lines for Energy Losses Decrease
PublikacjaCurrently, almost all medium voltage cable lines (MV) operate with the return wires earthed at both ends of the cable. Such a way of operation causes that during normal states of operation as well as during disturbances, e.g. short-circuits, in the return wires induce currents whose values mainly depend on the currents flowing in the phase wires. These currents in normal operating states are a source of additional energy losses...
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Design of power cable lines partially exposed to direct solar radiation – special aspects
PublikacjaPower cable lines are usually buried in the ground. However, in some cases, their ending sections are mounted along the supports of overhead lines. This leads to a situation where the cables are exposed to direct solar radiation and, consequentially, overheat. The paper presents the advanced computer modelling of power cables’ heating, considering their insolation as well as the effect of wind. The temperature and current-carrying...
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Analysis of Induced Voltages and Power Losses in High Voltage Power Cables for Selected Methods of Cables Sheaths Bonding
PublikacjaPower is increasingly supplied to city centres with 110 kV cable lines. This is a convenient way to supply power, and practically the only one possible in areas of dense urban development. A high-voltage cable contains a coaxial metallic sheath, in which in normal operation and in fault conditions (during short-circuits) significant line-to-earth voltages can be induced, which threatens electric shock and/or damage to the cable’s...
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AC motor feeding cable consequences on EMC performance of ASD
PublikacjaHigh level of conducted EMI emissions of adjustable speed drives (ASD) is one of the most difficult problems in contemporary applications. Many investigations are carried out in order to find more effective methods allowing to predict this emission at early stage of design, and therefore to predict adequate countermeasures. This paper deals with the method which allows to estimate by simulation the influence of motor feeding cable...
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Reference FEM model for SHM system of cable-stayed bridge in Rzeszów
PublikacjaThe paper presents the references model for structural health monitoring system (SHM) of cable-stayed bridge recently constructed in Rzeszów over Wisłok River. The SHM system is design to provide on-line information on the structure state and facilitate its maintenance procedures. The main feature of the SHM system is permanent observation of the dynamic behavior of the bridge with focus on cable vibrations. The paper discusses...
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The effect of cable duct diameter on the ampacity of high-voltage power cables
PublikacjaThe ampacity of power cables depends, among others, on the conditions of heat dissipation from the cable to the environment. Cables are usually laid directly in the ground, but in some sections, they may be placed in ducts, which adversely affects the ampacity of the cable line. The paper presents heat transfer phenomena for cables installed in pipe-type ducts filled with air. The effect of cable duct diameter on this ampacity...
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Safety issues referred to induced sheath voltages in high-voltage power cables – case study
PublikacjaLoad 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...
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Risk of power cables insulation failure due to the thermal effect of solar radiation
PublikacjaLow-voltage, as well as high-voltage power cable lines, are usually buried in the ground. The ampacity of the power cables in the ground mainly depends on the thermal resistivity of the soil, which may vary in a wide range. A common practice in power cable systems performance is to supply them from a pole of an overhead line. If so, a section of the line is located in free air and can be directly exposed to solar radiation. In...
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Subjective and Objective Quality Evaluation Study of BPL -PLC Wired Medium
PublikacjaThis paper presents results of research on the effectiveness of bi-directional voice transmission in a 6 kV mine cable network using BPL-PLC (Broadband over Power Line - Power Line Communication) technology. It concerns both emergency cable state (supply outage with cable shorted at both ends) and loaded with distorted current waveforms. The narrowband (0.5 MHz–15 MHz) and broadband (two different modes, frequency range of 3 MHz–7.5...
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Attempt to a Video-Transmission Capability in MV Mine Cable Network Using BPL-PLC Technology
PublikacjaThis article presents and discusses the attempt to transmit video content using the BPL-PLC (Broadband over Power Line - Power Line Communication) technology. It includes simulation results of a specially developed digital transmitter and receiver, dedicated to a given predefined 6 kV mining power cable. The effect of two different transmission modes (2-7 MHz and 3-7.5 MHz) and two types of coupling (capacitive-inductive and induction-inductive),...
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Quality Evaluation of Voice Transmission Using BPL Communication System in MV Mine Cable Network
PublikacjaThis article presents results of a quality evaluation study, considering voice transmission in a 6 kV medium voltage cable network using the BPL (Broadband over Power Line) communication system. The tests are carried out under real mining conditions for the selected power cable without voltage, earthed at both sides. Such a method of monitoring work conditions is of great importance, especially during a disaster. Power cables are...
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Effect of solar radiation on current-carrying capacity of PVC-insulated power cables – the numerical point of view
PublikacjaPower cables are usually buried in the soil, which results in their relatively high current-carrying capacity. However, there are cases in which the starting/final section of a cable line runs along a pole of an overhead power line. Power cables can be directly exposed to solar radiation then, and this negatively influences their current-carrying capacity as well as estimated life of the cables’ insulation. An analysis of thermal...
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Reliability assessment of an OVH HV power line truss transmission tower subjected to seismic loading
PublikacjaThe study focuses on the reliability of a transmission tower OS24 ON150 + 10, an element of an OVH HV power line, under seismic loading. In order to describe the seismic force, the real-life recording of the horizontal component of the El Centro earthquake was adopted. The amplitude and the period of this excitation are assumed random, their variation is described by Weibull distribution. The possible space state of the phenomenon...
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Voltage variations and their reduction in a rural low-voltage network with PV sources of energy
PublikacjaRenewable 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...
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Secured wired BPL voice transmission system
PublikacjaDesigning a secured voice transmission system is not a trivial task. Wired media, thanks to their reliability and resistance to mechanical damage, seem an ideal solution. The BPL (Broadband over Power Line) cable is resistant to electricity stoppage and partial damage of phase conductors, ensuring continuity of transmission in case of an emergency. It seems an appropriate tool for delivering critical data, mostly clear and understandable...