Search results for "Insulation"
showing 10 items of 61 documents
Electromagnetic Full-Wave Simulation of Partial Discharge Detection in High Voltage AC Cables
2019
Partial discharge (PD) activity in the insulation system of an electrical equipment can determine the failure of the whole apparatus. PD sensors are widely used in high-voltage electrical systems as the main elements of a detecting system oriented to real time monitoring. Recently, non-invasive sensors have been proposed in industrial applications for cable and other sensitive electrical parts: they are based both on capacitive and on the electromagnetic radiating coupling. In order to assess the real performance of a new sensor produced by a high voltage AC cables manufacturer, the paper proposes electromagnetic fullwave simulation results.
Dielectric and mechanical assessment of cellulosic insulation during transformer manufacturing
2021
Due to the impact of cellulose of paper insulation on transformer life, it is imperatire to remove moisture from the oil and the solid insulation. Several techniques have been implemented during manufacturing of power transformers to reduce water content in transformers. These drying processes can involve different costs and time, and they can damage the insulation paper. In this work, a drying process has been implemented in the laboratory trying to simulate the most aggressive conditions that can be suffered by the paper in transformer manufacturing in a real industry. Once the moisture content of papers was lower than 0.5%, the effect of the drying process on paper degradation was evalua…
Analyses of innovative glass blocks for BIPV: assessment of thermal and optical performance
2015
This paper illustrates the results of the performance analyses conducted on an innovative glass block integrated with thirdgeneration dye-sensitised solar cells (DSCs), designed to enable the construction of translucent and sustainable building envelopes. The analyses include the simulation of both thermal and optical performance with regard to different configurations of the photovoltaic (PV)-integrated glass block, and the results obtained are presented using two different programs: Comsol Multiphysics and WINDOW. The configurations may differ – for example, because of the position of the module inside the glass block, the type of DSC module used (composition, transparency, design) and th…
Energy Optimization of BIPV Glass Blocks: a Multi-software Study
2017
Abstract The aim of this paper is to show the results of the performance analyses carried out on four patented glass block configurations integrated with third-generation Dye-sensitized Solar Cell (DSC) modules. The analyses take into account the thermal, optical and electrical performance by using three different software (COMSOL Multiphysics, WINDOW, Zemax), also enabling to take into consideration the peculiar three-dimensional geometry of this innovative glazed product. Starting from these results, new configurations improved as for the thermal insulation, are also introduced and studied, in order to make further considerations about the applicability of this building component for the …
On the reliability of ASHRAE conduction transfer function coefficients of walls
2000
The transfer function method recommended by the ASHRAE can be considered the most modern tool currently available for the thermal analysis of a building. It is particularly well suited for use with a computer as it makes it possible to describe with great accuracy the internal heat gain of walls using a small set of coefficients. The present paper shows how to calculate sets of coefficients diverse from that proposed by Mitalas who first developed the method and on the basis of an unequivocal criterion, to prove the advantages in using them. The authors also investigated some of the paramount mathematical and physical aspects which affect the approximation degree of the ASHRAE method and, w…
A portable instrument for the location and identification of defects generating PD
2011
A portable instrument based on an antenna probe and suitable for partial discharge detection, have been characterized through both laboratory and on-site experiments carried out on coils and stator windings of ac rotating machines. The antenna probe allows the capture of electromagnetic waves in a bandwidth of 0.1–100 MHz. Pulse signals and ac supply voltage reference are obtained by means of high-pass and low-pass filters, respectively, so avoiding the need of a direct connection with the objects under test. By this way, real-time phase resolved partial discharge patterns can be derived. Results of a comparison of the diagnostic information provided by PD patterns due to conducted and irra…
Design, manufacturing and testing of a fast disconnecting system for the European target assembly concept of IFMIF
2013
The International Fusion Materials Irradiation Facility (IFMIF) will be equipped with a lithium target assembly to produce the required neutron flux for the irradiation of candidate fusion materials up to a damage rate of 100 dpa (cumulated damage in five years). The present European target assembly design is based on the so called replaceable backplate bayonet concept that was developed with the objective to simplify the maintenance operations for its refurbishment/replacement and to reduce the material for disposal as well. To this purpose it was also conceived to be attached to the lithium pipes and to the beam line by means of remotely operated connections based on clamped flanges with …
A statistic approach of cables ageing in MV lines on thermal and electrical combined stress
2006
The paper introduces a methodology that through a probabilistic characterisation of load for MV network, and implementing a life model for combined electric and thermal stresses, simulates the process of ageing of the insulating materials evaluating the expected life time of the cable. Such evaluation is necessary to the possibility of assuming less restrictive thermal overloading limits on electrical cables, with the consequential increase on reserve that cables could offer. A numerical example is reported to better explain the methodology
On the hygrothermal behavior of coconuts fiber insulators on green roofs.
2020
Coconut fibre insulators, represent an insulating material considered as “exotic”, which clashes with the doubts of his thermo-hygrometric behavior, in particular, in the case of covering technology such as green roofs, a technological solution adopted in the case of sustainable buildings or nearly zero energy building. Green roofs represent a valid constructive solution with high thermal performances, adopted in existing and new buildings. The purpose of the research regards the study of the thermo-hygrometric behavior of the concrete and Cross-Laminated Timber (CLT) slabs, insulated with coconut fibre-boards (CF) such as alternative synthetic insulators, referred to 10 different green roo…
Transient Electrical Behaviour of the TF Superconducting Coils of Divertor Tokamak Test Facility During a Fast Discharge
2022
The paper is focused on the electromagnetic analysis of the Toroidal Field (TF) superconducting coils of the Divertor Tokamak Test facility (DTT) when electrical transients occur in the TF coils system: for example, during the operations of the Fast Discharge Units (FDUs) and considering also, the simultaneous occurrence of a fault condition. During the FDU intervention, a transient voltage excitation lasting few microseconds occurs at the TF coil terminals and it electrically stresses the insulations of TF coils itsef. To investigate the voltage distribution across, inside and between different Double Pancakes (DPs) of each TF coil, a lumped parameters circuital model has been developed an…