Person: Da Silva, Izael
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- PublicationOn Site Calibration of Inductive Voltage Transformers(WSEAS, 2009) Da Silva, I. P.; Demetri, I.; De Silos, A. C.; Brandao, F. A (Jr); Da Silva, IzaelThe accuracy class of an IVT – Inductive Voltage Transformer – is typically assessed in laboratory installations either by comparing with another IVT presenting greater accuracy and traceable to a national laboratory or by using a capacitive divider. Calibration in the field is considered herein, using results obtained from typical open and short circuit tests and winding resistances, performed with common meters. A Möllinger & Gewecke graphic diagram is employed together with the results of an accuracy test previously carried out to determine the exact value of the winding turn relation and of the primary winding dispersion reactance. These values are used to calculate the phase and ratio errors, which must lie between definite limits, defined by the accuracy class of the instrument. Four commercial IVTs were tested to determine the validity of the procedure. The errors are compared with those obtained with the Schering-Alberti method (AC Bridge and comparison with standard IVT)
- PublicationInductive Voltage Transformers Calibration by the Parameters(WSEAS, 2010) Brandao, F.A; Da Silva, I. P.; Demetri, I.; De Silos, A. C.; Diaz, E. M; Da Silva, IzaelThe accuracy class of an IVT - Inductive Voltage Transformer - is typically assessed in laboratory installations either by comparing with another IVT presenting greater accuracy and traceable to a national laboratory or by using a capacitive divider. Calibration in the field using internal parameters is considered herein, using results obtained from typical open and short circuit tests and winding resistances, performed with common meters. A Möllinger & Gewecke graphic diagram is employed together with the results of an accuracy test previously carried out to determine the exact value of the winding turn relation and of the primary winding dispersion reactance. These values are used to calculate the phase and ratio errors, which must lie between definite limits, defined by the accuracy class of the instrument. Four commercial IVTs were tested to determine the validity of the procedure. The errors are compared with those obtained with the Schering-Alberti method (AC Bridge and comparison with standard IVT).
- PublicationImplementation of triple helix clusters procedure in the Sub-Sahara Africa energy sector(Universitätsbibliothek Fasanenstr, ) Da Silva, Izael; Da Silva, I. P.; Wassler, S.Penetration of decentralized power supply for households and commercial enterprises is low in Sub-Sahara Africa. Solar Home Systems (SHS), despite their widespread use in other continents have failed to attain much success in Africa. One of the reasons is the high rate of failure of existing implementations. Data shows earlier failure rates of 50%.1 This is largely attributed to poor quality of products used, inefficient installation, mismanagement and lack of maintenance. To address this problem, the Centre for Research in Energy and Energy Conservation (CREEC) is setting up a Solar PV test laboratory in Uganda. This paper describes the installation process and how to sustain the laboratory after implementation. The lab is intended to provide a forum for training, research and consultancy under CREEC. It is intended as a tool to implement the triple helix and clusters procedure in the PV industry in particular and the energy sector in a more general scope. This paper offers details covering the current situation of the energy sector in Uganda and how the lab supports capacity building in the university to support the upcoming demand.
- PublicationEnergy efficient building envelope designs for institutional buildings in East Africa(Domestic use of energy conference, ) Da Silva, Izael; Da Silva, I. P.; Ssekulima , E. B.To date, insufficient attention has been afforded to the design and energy performance of Institutional buildings in East Africa. As a result, most Institutional buildings in the region do not incorporate the issue of energy efficiency at the design, construction and utilization stages. Institutions are amongst the major consumers of energy in any country most of which is utilized within buildings, thus a thorough critique of the building envelope is necessary to reduce energy wastage within them. The aim of this paper is to present findings of the comparative study carried out on Institutional buildings at Strathmore University Nairobi, Kenya and Makerere University-Kampala, Uganda. The study mainly considered the effect of building envelope designs and orientation to the energy consumption of the buildings. ECOTECT, a Building energy performance analysis tool was employed to quantify the effect of both the conventional and Energy Efficient Building Envelopes to the overall energy consumption of the buildings. The research findings show that the overall energy consumption of Institutional buildings could easily be reduced by about 40% through the design of envelopes suited to the micro-climate of the particular site, proper selection of construction materials vis-a-vis their thermal performance, extensive use of daylighting, wise utilization of water and good building waste management systems as well as utilization of Energy Efficient Appliances within the building. The study also revealed that integration of a Building Management System would significantly reduce resource utilization within the building.
- PublicationInnovative Energy Access for Remote Areas “The LUAV-Light up a Village” Project(Springer Link, 2015-03-04) Da Silva, I. P.; Da Silva, IzaelThe Light-up a village (LUAV) program is a rural development initiative designed to improve access to modern energy solutions in remote areas of developing countries. The initiative addresses the challenge of Pico PV market penetration by empowering rural communities to actively participate in lighting up their own villages using micro-solar systems. The LUAV business model was designed by an energy company, Barefoot Power (BFP), which began the LUAV field in 2012 in Uganda. The program incorporates local SACCOs and Community Based Organizations (CBO) as well as local governmental bodies in the identification and recruitment of participants. A LUAV program is designed to involve at least 100 households per community by providing each home with its own power generation solar system to run lighting and mobile device charging services. The participating households are given the option to either pay for the micro solar power system upfront or to pay for it in 3–12 monthly installments. For this pilot program, BFP sourced for funding from private investors to operate a revolving fund which is managed the SACCOs and CBOs who have the mandate to manage debt recovery and keep the revolving fund active. Through this business model, 18 LUAV projects were implemented in Uganda during the 18 month trial period providing lighting and mobile charging services to 3,000 plus households. The program’s success has a growing interest and plans are underway to replicate it in South Sudan, Rwanda and Kenya in 2014. According to the latest count more than 7,000 households have adopted the micro-system through LUAV.
- PublicationEconomics of a Gasification Based Mini Grid - a case study of a 10 kW Unit in Uganda(2007-01) Da Silva, I. P.; Buchholz, T.; Volk, T; Tennigkeit, T; Da Silva, IzaelSmall-scale wood gasification systems have the potential to contribute to the rural electrification in Uganda. This paper presents an economic analysis of a 10 kW gasifier unit and its minigrid installed on a Ugandan farm. The bioenergy system has been running stable on a six hour daily base for seven months. When the gasifier is operated close to the rated capacity, the gasifier system is economically attractive compared to diesel generated electricity Results indicate that replicating successful wood gasification systems stipulates integration of sustainable fuelwood supply and viable business models.
- PublicationModels for conductor size selection in single wire earth return distribution networksGeofrey B.; Mohammad R. H.; Mikael, A.; Da Silva, I. P.; Da Silva, IzaelThe use of the ground as the current return path often presents planning and operational challenges in power distribution networks. This study presents optimization-based models for the optimal selection of conductor sizes in Single Wire Earth Return (SWER) power distribution networks. By using mixed integer non-linear programming (MINLP), models are developed for both branch-wise and primary-lateral feeder selections from a discrete set of overhead conductor sizes. The models are based on a mathematical formulation of the SWER line, where the objective function is to minimize fixed and variable costs subject to constraints specific to SWER power flow. Load growth over different time periods is considered. The practical application is tested using a case study extracted from an existing SWER distribution line in Namibia. The results were consistent for different network operating scenarios.
- PublicationReducing Carbon Emissions in a Third Level Educational Institution in Sub-Sahara Africa(Springer International Publishing Switzerland, 2015) Da Silva, I. P.; Ronoh, G.; Ouma, C.; Jerono, C.; Da Silva, IzaelThe effort to reduce carbon emissions as the arguably most prevalent cause of global warming has been a positive trend in most African countries. One of the most successful strategies towards reaching that goal is the shift from fossil fuel power generation to renewable sources of energy such as wind, hydro, geothermal and solar. As Kenya sits on the equator it enjoys an all year round insolation between 5 and 6 kW/m2/day which is more than double of the average insulation in Germany, a country where solar energy is widely used. Taking advantage of a green line of financial support created by the French Government, Strathmore University embarked in a project to install a 600 kW roof-top, grid connected solar PV system to cater for its electricity needs. Having as a background of the newly instituted Feed-in-Tariff regulation, the system is designed to produce more than the required self-consumption such that the extra power can be sold to the utility via a PPA (power purchase agreement) and the revenue used to pay for the electricity used by the university at night. This paper describes the whole process from the technical, regulatory, educational and financial aspect highlighting the positive and negative events along the path such that it can be useful for other private sector institutions interested in greening their sources of energy, invest in renewable energy and thus reduce their operation costs. The authors have written this work having in mind not only countries in Africa but all other countries which sit in the so called “solar belt”.
- PublicationBook review : Renewable Energy for Residential Heating and Cooling Policy Handbook(ICE Publishing, 2012-08) Da Silva, I. P.; Da Silva, IzaelThe scope of this book, as far as REHC projects are concerned, covers programme phases: portfolio planning, programme design, implementation and evaluation. It also covers market maturity stages from initial deployment to full market. It considers instruments such as: economic incentives, regulations, information and market activities. As the title mentions, the content is applicable to the residential sector only: new and existing buildings, including single and multi-family dwellings. As far as technology is concerned, it covers active solar thermal systems for air and water heating; biomass (pellets, wood and wood waste); geothermal (ground source and heat-pump) and finally heat-pump technologies based on ambient air heat (air-to-air and air-to-liquid)
- PublicationPower from wood gasifiers in Uganda: a 250 kW and 10 kW case study(Institution of Civil Engineers (ICE - Energy), ) Da Silva, Izael; Buchholz, T.; Da Silva, I. P.; Furtado, J.Wood gasification systems have the potential to contribute to the rural electrification in Sub-Saharan Africa. This paper presents an operational and economic analysis of two wood-based gasification systems (250 and 10 kW) installed in Uganda in 2007. Both systems proved their potential to compete economically with diesel generated electricity when operating close to the rated capacity. At an output of 150 kW running for ~12 h/day and 8 kW running for ~8h/day, the systems produced electricity at US$ 0.18 and 0.34/kWh, respectively. A stable electricity demand close to the rated capacity proved to be a challenge for both systems. Fuelwood costs accounted for ~US$0.03/kWh for both systems. Recovery of even a small fraction of the excess heat (22%) already resulted in substantial profitability gains for the 250 kW system. Results indicate that replicating successful wood gasification systems stipulates integration of sustainable fuelwood supply and viable business models.