Relevant bibliographies by topics / HVDC insulation

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
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Academic literature on the topic 'HVDC insulation'

Author: Grafiati
Published: 4 June 2021
Last updated: 17 June 2025

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Journal articles on the topic "HVDC insulation"

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Vera, Carlos, Fernando Garnacho, Joni Klüss, et al. "Validation of a Qualification Procedure Applied to the Verification of Partial Discharge Analysers Used for HVDC or HVAC Networks." Applied Sciences 13, no. 14 (2023): 8214. http://dx.doi.org/10.3390/app13148214.

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The insulation condition of HVDC grids consisting of cable systems, GIS, and converters should be monitored by partial discharge (PD) analysers using artificial intelligence (AI) tools for efficient insulation diagnosis. Although there are many experiences of PD monitoring solutions developed for the supervision of the insulation condition of HVAC grids using PD analysers, there are no standardised requirements for their qualification available yet. The international technical specification TS IEC 62478 provides general rules for PD measurements using electromagnetic methods but does not define performance requirements for qualification tests. HVDC and HVAC PD analysers must be tested by unambiguous test procedures. This paper compiles experiences of using PD analysers with HFCT sensors in HVAC grids (cable systems, GIS, and AIS) to define a qualification procedure for HVAC systems. This procedure is applicable to HVDC grids (cable systems, GIS, AIS, and converters) because the particularities related to the insulation behaviour under HVDC voltage are also considered. Representative PD sources are discussed in HVAC and HVDC positive and negative polarity. The PD pulse trend of representative insulation defects in HVDC cable systems is quite different from that of HVAC grids. Special attention should be paid to the acquisition of PD signals in HVDC grids since few pulses appear in solid insulations, mainly during voltage changes (polarity reversals or surges), but rarely in continuous operation with constant direct voltage. A synthetic PD simulator has been developed to reproduce trains of PD pulses or noise signals, similar to those that can appear in the power network. A set of three functionality tests has been developed for qualification of the diagnostic capabilities of PD analysers working up to 30 MHz addressed to HVDC or HVAC grids: (1) PD recognition test, (2) PD clustering test, and (3) PD location test. This qualification procedure has been validated by means of a round-robin test performed by five research institutes (RISE, FFII, TUDelft, TAU, and UPM) using commercial and in-development AI PD recognition and clustering tools to demonstrate its robustness and applicability. Applying this qualification procedure, two PD methods for electrical detection and prevention of insulation defects have been approved, one for HVAC and the other for HVDC grids.
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Jörgens, Christoph, and Markus Clemens. "A Review about the Modeling and Simulation of Electro-Quasistatic Fields in HVDC Cable Systems." Energies 13, no. 19 (2020): 5189. http://dx.doi.org/10.3390/en13195189.

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In comparison to high-voltage alternating current (HVAC) cable systems, high-voltage direct current (HVDC) systems have several advantages, e.g., the transmitted power or long-distance transmission. The insulating materials feature a non-linear dependency on the electric field and the temperature. Applying a constant voltage, space charges accumulate in the insulation and yield a slowly time-varying electric field. As a complement to measurements, numerical simulations are used to obtain the electric field distribution inside the insulation. The simulation results can be used to design HVDC cable components such that possible failure can be avoided. This work is a review about the simulation of the time-varying electric field in HVDC cable components, using conductivity-based cable models. The effective mechanisms and descriptions of charge movement result in different conductivity models. The corresponding simulation results of the models are compared against measurements and analytic approximations. Different numerical techniques show variations of the accuracy and the computation time that are compared. Coupled electro-thermal field simulations are applied to consider the environment and its effect on the resulting electric field distribution. A special case of an electro-quasistatic field describes the drying process of soil, resulting from the temperature and electric field. The effect of electro-osmosis at HVDC ground electrodes is considered within this model.
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Mikrut, Paweł, and Paweł Zydroń. "Numerical Modeling of PD Pulses Formation in a Gaseous Void Located in XLPE Insulation of a Loaded HVDC Cable." Energies 16, no. 17 (2023): 6374. http://dx.doi.org/10.3390/en16176374.

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Power cables are one of the key components of fast-growing HVDC transmission systems. The long-term reliability of HVDC cables is closely related to the occurrence of partial discharges (PDs) in their insulation systems. The article analyzes the conditions for the formation of PD pulses in gaseous voids located in the XLPE insulation of an HVDC cable. For this purpose, the MATLAB® procedure and the coupled electro-thermal simulation model implemented in COMSOL Multiphysics® software were used. The FEM model was used to study the effect of the applied voltage, the temperature field (created in the insulation of the loaded cable) and the location of the gaseous void (on cable radius) in the distribution and values of the electric field in the cable insulation. The model takes into account the influence of temperature and the electric field on the conductivity of the insulating material and relates the value of the PD inception field to the temperature/pressure of the gas inside the void. In the numerical simulation procedure, the time sequences of PDs arising in the gaseous defects of the HVDC cable insulation were analyzed, by observing changes caused by the increase in the temperature of the cable core. The model was used for a study of conditions for PD formation in models of three HVDC cables, for DC voltages from 150 kV to 500 kV. The critical dimensions of gaseous voids were also estimated for each of the analyzed cables, i.e., the dimension which, if exceeded, makes a void a source of PD.
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Bang, Seungmin, Ho-Seung Kim, Jae-Hong Koo, and Bang-Wook Lee. "Consideration of the Insulation Design Method on a ±200 kV Converter Valve Unit in an HVDC Converter Hall." Energies 14, no. 8 (2021): 2296. http://dx.doi.org/10.3390/en14082296.

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A converter valve unit, which converts Alternating Current (AC) to Directing Current (DC) and DC to AC, is one of the key elements of high voltage direct current (HVDC) transmission. The insulation design of a converter valve unit should be considered for air clearance according to the DC superimposed overvoltage and the insulator that maintains the insulation performance and the corona shield to suppress DC corona discharge. There is no prescribed standard for the insulation design of a converter valve unit. Moreover, insulation performance under an applied DC voltage has not yet been thoroughly investigated. Therefore, it is necessary to study the insulation design method of the converter valve unit. In this paper, consideration of the insulation design method on a ±200 kV converter valve unit in an HVDC converter hall is performed. The finite element method (FEM) is used to simulate the 3D model. Additionally, the safety factor (SF) is applied in accordance with the dielectric test in IEC 62271-1. As a result, an insulation design process on the converter valve unit is proposed and the insulation design is carried through the design factors. It is confirmed that design factors on the air clearance, insulator and corona shield have a significant effect on a highly reliable insulation design.
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Zhang, Yiyi, Keshuo Shi, Chunyan Zang, Wenchang Wei, Chuanhui Xu, and Junwei Zha. "Improved Insulation Properties of Polypropylenes in HVDC Cables Using Aqueous Suspension Grafting." Materials 15, no. 18 (2022): 6298. http://dx.doi.org/10.3390/ma15186298.

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Owing to its lack of crosslinking, polypropylene (PP) is considered an environmentally friendly alternative to crosslinked polyethylene as high-voltage direct current (HVDC) cable insulation. However, pure PP can accumulate space charges under a HVDC, and thus must be modified for use as an insulating material for HVDC cables. In this study, 4-methylstyrene is grafted onto PP using an aqueous suspension grafting method to improve its properties. The effects of the swelling time, reaction time, and 4-methylphenylene concentration on the reaction were investigated. The optimum process conditions were determined, including an optimum grafting ratio of 0.97%. The volume resistivity, ability to suppress space-charge accumulation, and DC breakdown strength of modified PP were also studied. Modified PP with a grafting ratio of 0.88% showed optimal space-charge suppression and the highest volume resistivity and breakdown strength. The work will facilitate the design and development of more efficient insulation materials for HVDC cables.
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Jörgens, Christoph, and Markus Clemens. "Modeling the electric field at interfaces and surfaces in high-voltage cable systems." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 39, no. 5 (2020): 1099–111. http://dx.doi.org/10.1108/compel-01-2020-0041.

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Purpose In high-voltage direct current (HVDC) cable systems, space charges accumulate because of the constant applied voltage and the nonlinear electric conductivity of the insulating material. The change in the charge distribution results in a slowly time-varying electric field. Space charges accumulate within the insulation bulk and at interfaces. With an operation time of several years of HVDC systems, typically the stationary electric field is of interest. The purpose of this study is to investigate the influence of interfaces on the stationary electric field stress and space charge density. Design/methodology/approach An analytic description of the stationary electric field inside cable insulation is developed and numerical simulations of a cable joint geometry are applied, considering spatial variations of the conductivity in the vicinity of the electrodes and interfaces. Findings With increasing conductivity values toward the electrodes, the resulting field stress decreases, whereas a decreasing conductivity results in an increasing electric field. The increased electric field may cause partial discharge, resulting in accelerated aging of the insulation material. Thus, interfaces and surfaces are characterized as critical areas for the reliability of HVDC cable systems. Research limitations/implications This study is restricted to stationary electric field and temperature distributions. The electric field variations during a polarity reversal or a time-varying temperature may result in an increased electric conductivity and electric field at interfaces and surfaces. Originality/value An analytical description of the electric field, considering surface effects, is developed. The used conductivity model is applicable for cable and cable-joint insulations, where homo- and hetero-charge effects are simulated. These simulations compare well against measurements.
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Yahyaoui, Hanen, Jerome Castellon, Serge Agnel, et al. "Behavior of XLPE for HVDC Cables under Thermo-Electrical Stress: Experimental Study and Ageing Kinetics Proposal." Energies 14, no. 21 (2021): 7344. http://dx.doi.org/10.3390/en14217344.

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The present work deals with the study of the electrical behavior of cross-linked polyethylene (XLPE) used for HVDC cable insulation. The aim is to better understand the influences of electrical and thermal stresses on the insulating material in order to provide useful information for designing HVDC cables. This study was carried out on Rogowski samples made of XLPE insulation with semiconductive electrodes, aged for more than 3 years (1220 days) at three different temperatures (70, 80 and 90 °C) under two DC electric fields (30 and 60 kV/mm). Dielectric loss factor, volume resistivity and space charge accumulation were measured. Results are analyzed and cross-correlated, in order to propose possible ageing kinetics.
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Azizian Fard, Mehrtash, Mohamed Emad Farrag, Alistair Reid, and Faris Al-Naemi. "Electrical Treeing in Power Cable Insulation under Harmonics Superimposed on Unfiltered HVDC Voltages." Energies 12, no. 16 (2019): 3113. http://dx.doi.org/10.3390/en12163113.

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Insulation degradation is an irreversible phenomenon that can potentially lead to failure of power cable systems. This paper describes the results of an experimental investigation into the influence of direct current (DC) superimposed with harmonic voltages on both partial discharge (PD) activity and electrical tree (ET) phenomena within polymeric insulations. The test samples were prepared from a high voltage direct current (HVDC) cross linked polyethylene (XLPE) power cable. A double electrode arrangement was employed to produce divergent electric fields within the test samples that could possibly result in formation of electrical trees. The developed ETs were observed via an optical method and, at the same time, the emanating PD pulses were measured using conventional techniques. The results show a tenable relation between ETs, PD activities, and the level of harmonic voltages. An increase in harmonic levels has a marked effect on development of electrical trees as the firing angle increases, which also leads to higher activity of partial discharges. This study of the influencing operational parameters of HVDC converters on power cable insulation is predicted to contribute to enhancements in cable design and progressive advancement in condition monitoring and insulation diagnostic techniques that can lead to more effective asset management in HVDC systems.
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Jörgens, Christoph, and Markus Clemens. "Electric Field and Temperature Simulations of High-Voltage Direct Current Cables Considering the Soil Environment." Energies 14, no. 16 (2021): 4910. http://dx.doi.org/10.3390/en14164910.

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For long distance electric power transport, high-voltage direct current (HVDC) cable systems are a commonly used solution. Space charges accumulate in the HVDC cable insulations due to the applied voltage and the nonlinear electric conductivity of the insulation material. The resulting electric field depends on the material parameters of the surrounding soil environment that may differ locally and have an influence on the temperature distribution in the cable and the environment. To use the radial symmetry of the cable geometry, typical electric field simulations neglect the influence of the surrounding soil, due to different dimensions of the cable and the environment and the resulting high computational effort. Here, the environment and its effect on the resulting electric field is considered and the assumption of a possible radial symmetric temperature within the insulation is analyzed. To reduce the computation time, weakly coupled simulations are performed to compute the temperature and the electric field inside the cable insulation, neglecting insulation losses. The results of a weakly coupled simulation are compared against those of a full transient simulation, considering the insulation losses for two common cable insulations with different maximum operation temperatures. Due to the buried depth of HV cables, an approximately radial symmetric temperature distribution within the insulation is obtained for a single cable and cable pairs when, considering a metallic sheath. Furthermore, the simulations show a temperature increase of the earth–air interface above the buried cable that needs to be considered when computing the cable conductor temperature, using the IEC standards.
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Schneider, H. M., J. F. Allaire, H. P. Lips, et al. "Insulation of HVDC converter stations." IEEE Transactions on Power Delivery 14, no. 2 (1999): 387–92. http://dx.doi.org/10.1109/61.754078.

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Dissertations / Theses on the topic "HVDC insulation"

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Bruce, Graham Philip. "Ageing of Outdoor Polymeric Insulation under HVDC." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505489.

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Nartey, Emmanuel Akuffo. "Oil/ Paper Insulation for HVDC: Conductivity of Oil." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13264.

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The work begins with a theoretical description of conductivity and the importance of this material property in the electrical power industry. The various theories describing high voltage conduction in highly insulating dielectric liquids are analysed to ascertain their propensity to explain the exponential rise in the conductivity of the insulating liquid at high fields.The work goes further to analyse the various methods and standards that are presently utilised in the measurement of conductivity of highly insulating oils. The short-comings of the present methods particularly the IEC 61620 and 60247 are identified. The physics behind the peculiar behaviour of the conductivity when stressed under high electric fields is described and analysed.Measurements carries out according to a standard, may not lead to useful results. Therefore, it is preferable to determine the conductivity under practical aspects and also to measure the different parameters on which the conductivity depends (1). A new method of carrying out conductivity measurements based on the use of triangular and sinusoidal input high voltage is used in this work.Conductivity analysis is carried out based on this method while time dependency, frequency dependency and field dependencies are studied.The results of the various results show a strong dependency of the resistance of the oil on the input electric field up to two powers of ten; when the electric field is varied from zero to 10 kV/mm for all frequencies. The frequency of input voltage has a minimum effect of the results of the conductivity up to 0.1 Hz; the only observable change is the increasing values of the capacitive current component of the measured total current.The time dependency of the resistance values shows a very remarkable variation of conductivity. There is an average of 3 times in the conductivity when the oil is stressed over a 24 hour period.Finally Comsol Multiphysics simulation is carried out to compare to the results of the experimental results obtained in the laboratory. The results of the current as well as the resistance values obtained using the comsol simulation bears great similarity to that of the laboratory experiments.
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Limbo, Beulah Sepo. "Insulator aging tests with HVAC and HVDC excitation using the tracking wheel tester." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2529.

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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.<br>ENGLISH ABSTRACT: Limited research results are available on the aging impacts of surface discharges for High Voltage Direct Current (HVDC) excitation on practical insulators using the Tracking Wheel Tester (TWT) methodology. This thesis gives details of an experimental investigation to compare the aging performance of insulator samples using the TWT for High Voltage Alternating Current (HVAC) and positive and negative polarity HVDC excitation. Two series of tests were performed. The first series of tests evaluated the aging of six insulator rods, namely three Room Temperature Vulcanized Silicone Rubber (RTV SR) coated glass samples and three uncoated glass samples. Three creepage distances were used for each of the test materials, namely 277 mm, 346 mm and 433 mm. The tests were conducted with HVAC excitation and the test methodology described in the IEC 61302 standard. The second series of tests involved the testing of actual insulator samples. The test voltage and conductivity of the salt water solution were also adapted. Six insulators from different manufacturers, representing different materials and specific creepage distances, were tested with HVAC and positive and negative polarity HVDC excitation. The test samples consisted of Ethylene Propylene Diene Monomer (EPDM), High Temperature Vulcanized Silicone Rubber (HTV SR), porcelain and SR coated porcelain insulators. The aging performance of the different test samples for the three types of excitation are compared in terms of peak leakage current, visual observations of surface degradation and hydrophobicity properties. The leakage current data for HVAC excitation shows that the insulators from the different manufacturers perform differently, even for the same type of material. The results also indicate differences in the way the surfaces degrade, as well as the rate of degradation. For insulators representing the same specific creepage distance, but different materials, it has been shown that the material does influence the aging performance. Comparison of the leakage current data for the HTV SR insulators from the same manufacturer, but with different specific creepage distances, shows that the specific creepage distance affect the aging performance significantly. In general, the test insulators showed higher peak leakage currents with HVDC excitation compared to HVAC excitation. The results for positive polarity HVDC excitation show that the dry band arcing, as well as the discharges, has the same form for all six insulators. The colour of the dry band discharges ranged from a blue-ish orange to a dark yellow, depending on the intensity of the leakage currents. The hydrophobic insulators, namely the HTV SR, EPDM and RTV SR coated porcelain insulators, had lost hydrophobicity within the first week of testing. The results for negative polarity HVDC excitation show severe surface degradation compared to the results for HVAC excitation. The effect of positive polarity HVDC excitation, however, seems to be more severe in terms of leakage currents and aging compared to negative polarity HVDC excitation.
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Lau, Wai Shyan. "Simultaneous space charge and current measurements in polyethylene insulation under HVDC conditions." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416497.

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Ghorbani, Hossein. "Characterization of Conduction and Polarization Properties of HVDC Cable XLPE Insulation Materials." Licentiate thesis, KTH, Elektroteknisk teori och konstruktion, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-180809.

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Since its first introduction in 1998, extruded direct current (DC) cable technology has been growing rapidly leading to many cable system installations with operation voltages up to 320 kV. Cable manufacturers invest heavily on technology development in this field and today extruded DC cable systems for operation voltages as high as 525 kV are commercially available. The electrical field distribution in electrical insulation under DC voltage is mainly determined by the conduction physics, therefore a good understanding of the DC conduction is necessary. In case of Cross-linked Polyethylene (XLPE) insulation, the presence of the peroxide decomposition products (PDP) is believed to influence its electrical properties. The PDP are volatile and therefore they may diffuse out of the samples during sample preparation and testing. Besides, the morphology of the XLPE is known to evolve over time even at moderate temperatures. Since the material may change during preparation, storage and even measurement, the procedure during all stages of the study should be chosen carefully. In this work, the physics of the dielectric response and conduction in XLPE is briefly discussed. The existing measurement techniques relevant to characterization of DC conduction in XLPE insulation materials are reviewed. The procedure for high field DC conductivity measurement is evaluated and recommendations for obtaining reproducible results are listed. Two types of samples are studied, i.e. thick press molded samples and thick plaque samples obtained from the insulation of in-factory extruded cables. For press molded samples, the influence of the press film used during press molding and the effect of heat-treatment on the electrical properties of XLPE and LDPE are studied. High field DC conductivity of XLPE plaque samples is measured with a dynamic electrode temperature to simulate the standard thermal cycles. Investigations show that using PET film during press molding leads to higher apparent DC conductivity and dielectric losses when compared to using aluminum foil. The influence of heat-treatment is different depending on the press film. High field DC conductivity measurements and chemical composition measurement of samples obtained from the cable insulation are in good agreement with the results obtained from the full scale measurements. Finally a non-monotonic dependence of apparent DC conductivity to temperature of some samples pressed with PET film is discovered which to the author’s best of knowledge has not been previously reported in the literature.<br>Sedan det första införandet i 1998 har extruderad likspänning (DC) kabeltekniken vuxit snabbt och har lett till många existerande kabelsysteminstallationer med driftspänningar upp till 320 kV. Kabeltillverkare investerar kraftigt i teknikutveckling inom detta område och idag finns extruderade DC kabelsystemen tillgängliga för driftspänningar så höga som 525 kV. Elektrisk fältfördelning i isolationsmaterial under hög DC spänning, beror framförallt på materialets elektriska ledningsfysik, därför är en bra förståelse av DC ledningsförmåga nödvändig. Isolationsmaterial av tvärbunden polyeten (PEX) innehåller tvärbindningsrestgaser som tros påverka materialets elektriska egenskaper. Restgaserna är flyktiga och kan diffundera bort från proven under preparering och mätning, även under måttliga temperaturer. PEX materialets morfologi ändras även med tiden. Med tanke på att materialet kan ändras under provpreparering, lagring och även vid mätning, så måste samtliga steg ovan väljas mycket försiktigt. I detta arbete diskuteras grundläggande fysik för dielektrisk polarisering och ledningsförmåga i PEX-isolation tillsammans med granskning av existerande mätteknik relevant för karakterisering av ledningsförmåga i PEX. Procedurer för mätning av DC ledningsförmåga under höga elektriska fält är undersökta och rekommendationer för reproducerbar mätningar är framtagna. Två typer av prover är studerade, tjocka pressade plattor och tjocka plattor som ursvarvats från kommersiell tillverkade högspänningskablar. För pressade plattor, studerades effekten utav press-filmens påverkan på de elektriska egenskaperna hos PEX och LDPE. Påverkan av värmebehandling på DC ledningsförmåga av PEX plattor studerades också. Slutligen studerades DC ledningsförmåga av PEX och LDPE plattor under höga DC fält och med dynamisk temperatur på elektroderna med syftet att efterlikna standardvärmecyklingar. Undersökningarna visade att användningen av PET filmer under pressning av plattor ledde till högre DC ledningsförmåga och högre dielektriska förluster i proven i jämförelse med användning av aluminiumfolie. Påverkan utav värmebehandling är olika beroende på typ av film som används pressningen. Det finns en stark korrelation mellan resultaten från DC konduktivitet och kemisk komposition mätningar från plattor skaffat från kabelisolation och resultaten från fullskaliga kabelmätningar. Slutligen, upptäcktes ett icke monotont beroende av DC konduktivitet hos PEX och LDPE plattor på temperatur som tidigare inte rapporterats i litteraturen.<br><p>QC 20160125</p>
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Bilock, Alexander. "Probabilistic Approach to InsulationCoordination." Thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-296483.

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The present work was performed at HVDC ABB as an initial study on how to adopt probabilistic concepts into the VCSHVDC insulation coordination. Due to large voltage levels in HVDC applications the corresponding insulation need to be properly addressed to ensure a safe, economical and reliable operation. Traditionally, only the maximum overvoltage is considered, where no adoption to the shape of the overvoltage distribution is regarded. Use of probabilistic concepts in the insulation coordination procedure can ideally reduce insulation margins with a maintained low risk of flashover. Analysis and understanding of probabilistic concepts of AC systems is needed in order to implement the concepts into VSC-HVDC. With use of advanced VSC-HVDC models, faults are simulated with varied fault insertion time in PSCAD. The resulting overvoltages from the simulation is gathered using different statistical methods in order to obtain the approximated overvoltage distribution. It was found from the simulation results that use of a Gaussian distribution is inappropriate due to shape variety in the overvoltage distributions. Instead, Kernel Density Estimate can serve as a flexible tool to approximate overvoltage distributions with a variety in number of modes and shape. The retrieved approximated overvoltage distributions are compared with the insulation strength in order to calculate the risk of flashover. The comparison shows that the insulation can be tuned in order to match set requirements. The thesis work should be seen as pilot study, where key problems have been pointed out and recommended further studies are proposed.
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Oldervoll, Frøydis. "Electrical and Thermal Ageing of Extruded Low Density Polyethylene Insulation Under HVDC Conditions." Doctoral thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2000. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-208.

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<p>After extensive research during the last decades extruded polymeric insulation is now becoming an alternative to the traditional oil-paper systems for high voltage DC (HVDC) cables. Durability is of great importance for power cables, and the main purpose of this work has been to increase the knowledge of factors controlling the endurance of an extruded polymeric insulation under HVDC conditions. The effect of electrical and thermal ageing on electrical properties like space change accumulation, DC breakdown strength and electrical tree initiation has been investigated and related to changes in morphology, oxidation level and antioxidant concentration.</p><p>Low density polyethylene (LDPE) with and without an antioxidant additive was selected as insulating material. Test objects with plane electrodes or needle-plane electrodes were prepared by pressure moulding and equipped with aluminium electrodes. Iron particles with a diameter of 45 – 55 μm were introduced to simulate conducting contaminations in the insulation. The test objects were subjected to thermal ageing of 70°C and 90°C and the applied electrical field during ageing ranged from zero to 150 kV/mm. ageing was conducted both with constant DC polarity and with polarity reversals. The ageing period ranged from 4 weeks to 5 months.</p><p>Thermal oxidation was observed in LDPE without antioxidant and this clearly affected the electrical properties. The DC breakdown voltage was reduced by 40% and this was explained by enhanced high-field conduction and increased joule heating due to the oxidation products. It was found that oxidation was prohibited when the thickness of the aluminium electrodes increased. </p><p>Introduction of iron particles reduced the short term DC strength by 20 – 30%, but during long term ageing with constant DC voltage no difference was observed between test objects with and without particles. This was probably caused by screening of the particles by accumulated space charge. </p><p>The experiments showed that abrupt grounding or polarity reversal initiated electrical trees from the needle-electrodes. The longest trees were observed when the test objects had first been subjected to thermal and electrical ageing. The tree formation was caused by the high electrical field arising when the accumulated homocharge around the needle was converted to heterocharge at polarity or grounding,</p><p>The following main conclusions were made from the work:</p><p>*Oxidation is detrimental and must be avoided in HVDC insulation.</p><p>* The antioxidant additive can have a negative influence on the electrical properties under HVDC stress.</p><p>*Polarity reversal or abrupt grounding can initiate electrical trees from protrusions present at the electrode-insulation interface of a HVDC insulation system. </p>
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RIZZO, Giuseppe. "Pulsed Electro-Acoustic space charge apparatus – qualifying, testing and monitoring of insulation for HVDC cables and accessories." Doctoral thesis, Università degli Studi di Palermo, 2022. http://hdl.handle.net/10447/533110.

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Hägerbrand, Jonathan. "Measurements of resistivity in transformer insulation liquids." Thesis, Uppsala universitet, Institutionen för elektroteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413804.

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This thesis focuses on measuring techniques and results of resistivity in four commercially available insulating transformer oils: mineral oil, ester oil and two isoparaffin oils. Two measuring techniques, the industrially used diagnostic system for electrical insulation IDA and the Labview implemented Triangular Method, are used for resistivity measurements and the techniques are compared, a correction algorithm to the triangular method is suggested. Dielectric properties of mineral &amp; ester and isoparaffin A&amp;B mixtures are investigated, it is experimentally shown that the transformer oils that show high resistivity also show low loss factor. The effect moisture has on resistivity in mineral and ester oil are shown both in terms of relative humidity and actual water content in parts per million. A previous measurement cell is redesigned, the cell is manufactured in copper and gold. It is found that the material choice of the cell significantly affects the resistivity measurements. The electrical double layer and contact resistance between the oil and cell are investigated as a way to explain the difference in measured resistivity. These experiments are limited to the mineral oil and isoparaffin oil A, it is found that contact resistance is a plausible explanation. The electrical double layer is fairly constant for both oils and the Debye length of the double layer is negligible compared to the total distance between the electrodes of the cell. Lastly, the field of insulating transformer oils and its future is discussed, from data obtained regarding the dielectric properties and environmental aspects of the four transformer oils used in this study. A positive trend which combines the high insulating properties with good biodegradability qualities is found. Suggesting a positive future in the field of insulating transformer oils. The results found in this thesis can be used as a basis for future theses regarding transformer oils used for HVDC applications.
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10

Pallon, Love. "Polyethylene/metal oxide nanocomposites for electrical insulation in future HVDC-cables : probing properties from nano to macro." Doctoral thesis, KTH, Polymera material, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193591.

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Nanocomposites of polyethylene and metal oxide nanoparticles have shown to be a feasible approachto the next generation of insulation in high voltage direct current cables. In order to reach an operationvoltage of 1 MV new insulation materials with reduced conductivity and increased breakdown strengthas compared to modern low-density polyethylene (LDPE) is needed.In this work polyethylene MgO nanocomposites for electrical insulation has been produced andcharacterized both from an electrical and material perspective. The MgO nanoparticles weresynthesized into polycrystalline nanoparticles with a large specific surface area (167 m2 g–1). Meltprocessing by extrusion resulted in evenly dispersed MgO nanoparticles in LDPE for the silane surfacemodified MgO as compared to the unmodified MgO. All systems showed a reduction in conductivityby up to two orders of magnitude at low loading levels (1–3 wt.%), but where the surface modifiedsystems were able to retain reduced conductivity even at loading levels of 9 wt.%. A maximuminteraction radius to influence the conductivity of the MgO nanoparticles was theoretically determinedto ca. 800 nm. The interaction radius was in turn experimentally observed around Al2O3 nanoparticlesembedded in LDPE using Intermodulation electrostatic force microscopy. By applying a voltage on theAFM-tip charge injection and extraction around the Al2O3 nanoparticles was observed, visualizing theexistence of additional localized energy states on, and around, the nanoparticles. Ptychography wasused to reveal nanometre features in 3D of electrical trees formed under DC-conditions. Thevisualization showed that the electrical tree grows by pre-step voids in front of the propagatingchannels, facilitating further growth, much in analogy to mechanical crack propagation (Griffithconcept). An electromechanical effect was attributed as possible mechanism for the formation of the voids.<br>Nanokompositer av polyeten och metalloxidpartiklar anses vara möjliga material att använda i morgondagens isolationshölje till högspänningskablar för likström. För att nå en transmissionsspänning på 1 MV behövs isolationsmaterial som i jämförelse med dagens polyeten har lägre elektrisk ledningsförmåga, högre styrka mot elektriskt genomslag och som kan kontrollera ansamling av rymdladdningar. De senaste årens forskning har visat att kompositer av polyeten med nanopartiklar av metalloxider har potential att nå dessa egenskaper. I det här arbetet har kompositer av polyeten och nanopartiklar av MgO för elektrisk isolation producerats och karaktäriserats. Nanopartiklar av MgO har framställts från en vattenbaserad utfällning med efterföljande calcinering, vilket resulterade i polykristallina partiklar med en mycket stor specifik ytarea (167m2 g-1). MgO-nanopartiklarna ytmodifierades i n-heptan genom att kovalent binda oktyl(trietoxi)silan och oktadekyl(trimetoxi)silan till partiklarna för att skapa en hydrofob och skyddande yta. Extrudering av de ytmodifierade MgO nanopartiklarna tillsammans med polyeten resulterade i en utmärkt dispergering med jämnt fördelad partiklar i hela kompositen, vilket ska jämföras med de omodifierade partiklarna som till stor utsträckning bildade agglomerat i polymeren. Alla kompositer med låg fyllnadsgrad (1–3 vikt% MgO) visade upp till 100 gånger lägre elektrisk konduktivitet jämfört med värdet för ofylld polyeten. Vid högre koncentrationer av omodifierade MgO förbättrades inte de isolerande egenskaperna på grund av för stor andel agglomerat, medan kompositerna med de ytmodifierade fyllmedlen som var väl dispergerade behöll en kraftig reducerad elektrisk konduktivitet upp till 9 vikt% fyllnadshalt. Den minsta interaktionsradien för MgO-nanopartiklarna för att minska den elektriska konduktiviten i kompositerna fastställdes med bildanalys och simuleringar till ca 800 nm. Den teoretiskt beräknade interaktionsradien kompletterades med observation av en experimentell interaktionsradie genom att mäta laddningsfördelningen över en Al2O3-nanopartikle i en polyetenfilm med intermodulation (frekvens-mixning) elektrostatisk kraftmikroskop (ImEFM), vilket är en ny AFM-metod för att mäta ytpotentialer. Genom att lägga på en spänning på AFM-kantilevern kunde det visualiseras hur laddningar, både injicerades och extraherades, från nanopartiklarna men inte från polyeten. Det tolkades som att extra energinivåer skapades på och runt nanopartiklarna som fungerar för att fånga in laddningar, ekvivalent med den gängse tolkningen att nanopartiklar introducera extra elektronfällor i den polymera matrisen i nanokompositer. Nanotomografi användes för att avbilda elektriska träd i tre dimensioner. Avbildningen av det elektriska trädet visade att tillväxten av trädet hade skett genom bildning av håligheter framför den framväxande trädstrukturen. Håligheterna leder till försvagning av materialet framför det propagerande trädet och förenklar på det sättet fortsatt tillväxt. Bildningen av håligheter framför trädstrukturen uppvisar en analogi till propagering av sprickor vid mekanisk belastning, i enlighet med Griffiths koncept.<br><p>QC 20161006</p>
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Books on the topic "HVDC insulation"

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Du, Boxue, ed. Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-9731-2.

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Allais, A., and S. Nguefeu. HVDC Lines. Wiley & Sons, Incorporated, John, 2016.

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Allais, A., and S. Nguefeu. HVDC Lines. Wiley & Sons, Incorporated, John, 2016.

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Allais, A., and S. Nguefeu. HVDC Lines. Wiley & Sons, Incorporated, John, 2016.

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Allais, A., and S. Nguefeu. HVDC Lines. Wiley & Sons, Incorporated, John, 2016.

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Du, Boxue. Polymer Insulation Applied for HVDC Transmission. Springer Singapore Pte. Limited, 2021.

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Du, Boxue. Polymer Insulation Applied for HVDC Transmission. Springer Singapore Pte. Limited, 2020.

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Kumar, Raj. EXPERIMENTAL INVESTIGATION on THERMAL INSULATION PERFORMANCE of GLASSFIBER and EPS for HVAC APPLICATIONS Engineering Projects. Independently Published, 2019.

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Book chapters on the topic "HVDC insulation"

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Zha, Jun-Wei, Ming-Sheng Zheng, Wei-Kang Li, George Chen, and Zhi-Min Dang. "Polypropylene Insulation Materials for HVDC Cables." In Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9731-2_4.

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Li, Chuanyang, Chuanjie Lin, and Tohid Shahsavarian. "HVDC Spacers by Adaptively Controlling Surface Charges." In Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9731-2_14.

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Chen, Chi, Xia Wang, Kai Wu, and Chuanhui Cheng. "Space Charge Characteristics of Coaxial Cable Insulation." In Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9731-2_7.

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Wang, Shihang. "DC Insulation Performance of Crosslinked Polyethylene for HVDC Cables." In Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9731-2_1.

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Yang, Zhuoran, Zhonglei Li, Honghua Xu, Hao Wang, Wei Chen, and Zihe Yang. "Charge Properties of SiC/SiR Composites with Nonlinear Conductivity at Different Temperatures." In Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9731-2_10.

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Su, Jingang, Boxue Du, Tao Han, Zhonglei Li, Liqiang Wei, and Peng Zhang. "Effect of Temperature and Mechanical Stress on Charge Transport and Ageing Properties of EPDM for Cable Accessories." In Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9731-2_11.

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Li, Jin, Chenlei Han, Boxue Du, and Tatsuo Takada. "Theoretical Model and Suppressing Method of Interface Charge Accumulation in HVDC Cable Accessory: A Review." In Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9731-2_12.

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Zhao, Yushun, Kerong Yang, Song Zhang, Bin Du, Xuepei Wang, and Yuanhan He. "Epoxy Resin Insulating Composites for Vacuum Cast Electrical Insulators of GIS." In Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9731-2_13.

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Zhang, Boya, and Guixin Zhang. "Surface Charge Accumulation on Insulators in HVDC Gas-Insulated Systems: Measurement, Characteristics, and Suppression." In Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9731-2_15.

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Xie, Qing, Haoou Ruan, Jun Xie, et al. "Nano-Modification for Enhancing the DC Surface Insulation Strength of Epoxy Resin." In Polymer Insulation Applied for HVDC Transmission. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9731-2_16.

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Conference papers on the topic "HVDC insulation"

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Shen, Jie, Yuan Li, Shenglong Li, et al. "The Partial Discharge Characteristics of Oil-Paper Needle-Plane Insulation Defects Under Pulsating DC Voltage." In 2024 International Conference on HVDC (HVDC). IEEE, 2024. http://dx.doi.org/10.1109/hvdc62448.2024.10722893.

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Zhao, Ziwei, Muhammad Awais, Yuantao Zhao, Qi Tang, Feng Xia, and Xiangrong Chen. "Investigation on Dielectric Insulation Properties of ±525 kV HVDC XLPE Material for High Temperatures Applications." In 2024 International Conference on HVDC (HVDC). IEEE, 2024. http://dx.doi.org/10.1109/hvdc62448.2024.10723025.

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Minkai, Wang, Li Longfei, Liu Lei, et al. "Replacement Scheme and Insulation Performance Analysis of Bushing on Network Dide of 800kV Converter Transformer." In 2024 International Conference on HVDC (HVDC). IEEE, 2024. http://dx.doi.org/10.1109/hvdc62448.2024.10722938.

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Ma, Yuegui, Zigang Shen, and Qi Zhou. "Research and Application of Sunscreen and Heat Insulation Technology in Power Systems under Extreme High-Temperature Environment." In 2024 International Conference on HVDC (HVDC). IEEE, 2024. http://dx.doi.org/10.1109/hvdc62448.2024.10722992.

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Diban, Bassel, Giovanni Mazzanti, Paolo Seri, et al. "Characterization of Isotactic-Polypropylene-Based Compounds for HVDC Cable Insulation." In 2024 IEEE 5th International Conference on Dielectrics (ICD). IEEE, 2024. http://dx.doi.org/10.1109/icd59037.2024.10613139.

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Niittymäki, Minna, Kari Lahti, Ilkka Rytöluoto, et al. "Screening of Suitable Random Copolymer Polypropylene Blends for HVDC Cable Insulation." In 2024 IEEE 5th International Conference on Dielectrics (ICD). IEEE, 2024. http://dx.doi.org/10.1109/icd59037.2024.10613125.

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Hui, Sisi, Linzhen Fan, Zheng Zhao, and Lingfei Xiong. "Research on Insulation Coordination in MMC-HVDC for Wind Farm Integration." In 2024 The 9th International Conference on Power and Renewable Energy (ICPRE). IEEE, 2024. https://doi.org/10.1109/icpre62586.2024.10768328.

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Zhang, Chong, Zhaoliang Xing, Pengfei Wu, et al. "Study on the high frequency insulation strength of disiloxane modified polyimide film." In 2020 4th International Conference on HVDC (HVDC). IEEE, 2020. http://dx.doi.org/10.1109/hvdc50696.2020.9292671.

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Zheng, Jiankang, Qiming Gong, Hai Nan, Xiaoting Su, Cheng Duan, and Mingyang Xu. "Research on XLPE Insulation Failure Characteristics of DC Cables in Fire Environmet." In 2020 4th International Conference on HVDC (HVDC). IEEE, 2020. http://dx.doi.org/10.1109/hvdc50696.2020.9292857.

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Weiwang, Wang, He Jiefeng, Wang Xin, Liu Ying, and Li Shengtao. "Analysis of Electric Field Stress and Dielectric Loss in Insulation of Magnetic Component for Cascaded Power Electronic Transformer." In 2020 4th International Conference on HVDC (HVDC). IEEE, 2020. http://dx.doi.org/10.1109/hvdc50696.2020.9292863.

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Reports on the topic "HVDC insulation"

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Pfluger, Rainer, and Alexander Rieser, eds. Conservation compatible energy retrofit technologies: Part IV: Documentation and assessment of energy and cost-efficient HVAC-systems and strategies with high conservation compatibility. IEA SHC Task 59, 2021. http://dx.doi.org/10.18777/ieashc-task59-2021-0007.

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Historic building restoration and renovation requires sensitivity to the cultural heritage, historic value, and sustainability (i.e., building physics, energy efficiency, and comfort) goals of the project. Heat recovery ventilation can contribute to the mentioned goals if ventilation concepts, and airflow distribution is planned and realized in a minimally invasive way. Compared to new buildings, the building physics of historic buildings are more complicated in terms of hygrothermal performance. In particular if internal insulation is applied, the need for dehumidification is needed for robust and risk-free future use, while maintaining the building’s cultural value. As each ventilation system has to be chosen and adapted individually to the specific building, the selection of the appropriate system type is not an easy task.
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