37 research outputs found
THERMAL ANALYSIS OF POWER LINES: METHODOLOGIES AND APPLICATIONS
No full textThe thermal analysis of cables aims at computing the temperature rise inside the cables due to the heat generated inside the conductor during the normal operation of the cable. The temperature limit of the cable is given by the insulation material: if this limit was exceeded the insulation would be damaged. For this reason it is necessary to calculate the cable ampacity that keeps the cable temperature under the insulation limit. The heat generated by the conductor ows radially from inside to outside (the surrounding medium can be air or earth, in case of buried cable) through all the cable layers. The cable ampacity is calculated solving a circuit that represents the thermal behaviour of the cable. The Standards, in particular the Standard IEC 60287, consider many possible congurations. The Standard IEC 60287 allows to choose the cable (it is possible to specify the dimension and the material of each cable layer) and the layout (cables in air or buried). In case of underground cables, the user can decide how the cables are buried (directly in ground or in conduits), the material surrounding the system and the ambient temperature. The Standard IEC 60287 has some lacks: - it does not consider the presence of external heat sources in addition to the power line cables; - it performs only a steady-state analysis; - it is useful only when a tridimensional analysis is not necessary. In the normal practice, in case of buried cables, it is not unusual that there are external heat sources in addition to the power line cables. And the power line is not always supplied by a costant current; it can be supplied by a load curve and there can be a transient. Moreover in some congurations the 2D section changes along the third dimension, therefore a 2D model is very conservative: a 3D analysis is useful. In all these cases where the Standards are not applicable, another method can be applied. The numerical solver used allows to: - consider any heat sources; - study the transient behaviour; - analize a 3D model. The method has been applied to study a particular part of the power line: the junction zone. In the junction zone the magnetic eld is higher and it can be necessary to shield the power line. The shielding method considered is the High Magnetic Coupling Passive Loop technology. If this system is applied a thermal analysis of the junction zone has to be performed because of the presence of a new set of conductors, in addition to the power line cables. In this case the Standard IEC 60287 is not applicable because: - there are heat sources dierent from the power line cables; - a 3D model is necessary to study the eect of the ending connections of HMCPL and the cable joint
Effects of frequency dependent material properties on the computation of transient eddy currents in human body
No full textThe high magnetic coupling passive loop: A steady-state and transient analysis of the thermal behavior
No full textThis paper deals with a new concept of technology for the mitigation of the magnetic field produced by underground power lines called "High Magnetic Coupling Passive Loop" (HMCPL). The working principle of this technique is the creation of a current with the same amplitude but opposite phase for each source conductor, in order to nullify the magnetic field in a specified region. Since the number of thermal sources in the shielding region is roughy doubled, the aim of the paper is the investigation of the thermal behavior of HMCPL directly buried in the ground, both in transient and in steady-state conditions. The study is carried out with simulations in order to verify any possible configurations of the shield. Results confirm that HMCPL is a safe technology which does not modify the thermal behavior of the power lin
Numerical simulation of heart-current factors and electrical models of the human body
No full textContact with energized parts at different potentials may cause the circulation of body current and the possible inception of the ventricular fibrillation, which is generally considered the most life-threatening effect imposed on the cardiac muscle. The heart-current factors currently present in international standard have been determined thanks to measurements on cadavers, as well as experiments with volunteers. These methodologies are both questionable, as measurements depends on the nature of the probes and their position with respect to the heart; in addition, volunteers cannot obviously be exposed to dangerous levels of currents. Due to the aforementioned difficulties in experimental verifications, the authors propose the use of numerical techniques to investigate the behavior of the human body when is subject to electric fields. This work is based on a mathematical representation of the human anatomy, which takes into account the boundaries of the internal organs. The simulations carried out and documented in this paper, show results that do not entirely match the published IEC heart-current factors; most noticeably, for the pathways hands-feet, right hand-feet and left hand-right foot, the heart-current factors seem to be overestimated by the IEC
Energy Saving in Social Housing: an Innovative ICT Service for Occupant Behaviour
No full textThe European Commission is supporting many projects in the field of energy saving, with the aim to improve inhabitants behavior and to help Europe to meet emission targets. The objective of the Balanced European Conservation Approach - ICT services for resource saving in social housing (BECA) Project is to enable consumption reduction of key resources in European Social Housing by providing usable ICT-based services for Resource Management and Resource Use Awareness, directly by tenants. The project is developing a range of ICT innovative services to be provided to the inhabitants of 7 different European cities: Örebro (Sweden), Manresa (Spain), Darmstadt (Germany), Torino (Italy), Havirov (Czech Republic), Ruse (Bulgaria), and Belgrade (Serbia). The ICT service will deliver to tenants information with direct timely and comprehensible feedback on the impact of their behavior on a full range of resource uses, thereby enabling tenants to save energy and water. This paper describes the project highlighting the adoption of ICT service in Torino and the initial results
Smart energy users in social housing by BECA ICT service
No full textThe European Commission is supporting many projects to reach the European targets in energy savings and diffusion of renewable resources. The BECA — Balanced European Conservation Approach — ICT Service for Resources Saving in Social Housing, is a project in the frame of 7th ICT-PSP program that involves seven different cities in Europe. The target of the project is to build, and spread among the final users, ICT based services that can improve the energy use awareness of people, without a specific education in the use of energy. Some ICT based services: web services and sms services have been developed and applied in three different sites in Torino (Italy), taking into account the peculiarities of each site. In order to modify the behavior of the final users about energy, an ICT service that allows the comparison of energy consumption (actual consumptions vs past consumptions and consumptions vs middle user's consumptions), has been developed. The ICT service has been made available to the final users and operators in the managing staf
Energy networks in sustainable cities: Polycity project and the case study of Turin – Arquata
No full textMagnetic field mitigation of power lines by means of passive loop: technical and economical optimization
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