GPR applied to mapping utilities along the route of the Line 4 (yellow) subway tunnel construction in Sao Paulo City, Brazil

The rapid industrial development and disorganized population growth in huge cities bring about various urban problems due to intense use of physical space on and below the surface. Subsurface problems in metropolitan areas are caused by subway line construction, which often follows the routes of utility networks, such as electric and telephone cables, water and gas pipes, storm sewers, etc. Usually, the main problems are related to damage or destruction of preexisting utilities, often putting human lives at risk. With the purpose of minimizing risks. GPR-profiling with 200 MHz antennae was done at two sites, both located in downtown Sao Paulo, Brazil. The objectives of this work were to map utilities or existing infrastructure in the subsurface in order to orient the construction of the Line 4 (yellow) subway tunnel in Sao Paulo. GPR profiles can detect water pipes, utility networks in the subsurface, and concrete foundation columns or pilings in subsoil up to 2 m depth. In addition. the GPR profiles also provided details of the target shapes in the subsurface. GPR interpretations combined with lithological information from boreholes and trenches opened in the study areas were extremely important in mapping of the correct spatial distribution of buried utilities at these two sites in Sao Paulo. This information improves and updates maps of utility placement, serves as a basis for planning of the geotechnical excavation of the Line 4 (yellow) subway tunnel in Sao Paulo, helps minimize problems related to destruction of preexisting utilities in the subsoil, and avoids risk of dangerous accidents. (C) 2012 Elsevier B.V. All rights reserved.

Diagnostic of Silicon Carbide Surge Arresters using Leakage Current Measurement

Nowadays, the zinc oxide surge arresters (ZnO) are widely used in power systems, however, a large number of silicon carbide surge arresters (SiC) are still in service in the utilities. On the other hand, it is not possible to replace all SiC surge arresters in a short time period, being necessary to review the maintenance program taking into account the surge arresters that are more degraded. In this context, a research project was established between the University of Sao Paulo and the electrical utility CTEEP, aiming the investigation of its SiC surge arresters. This work shows that the leakage current measurement, a diagnostic method for the ZnO surge arresters, can provide useful information related to the condition of the SiC surge arresters. Analysis of the amplitude and distortion of the leakage current, also considering thermovision measurements, resulted in better evaluation of the SiC surge arresters.

La regulación de los servicios de electricidad en Argentina y Brasil (1890-1962)

El artículo analiza la evolución de la regulación del sector eléctrico en Argentina y Brasil entre 1890 y 1960. Desde la instalación de las primeras usinas eléctricas a fines del siglo diecinueve hasta los años treinta, el control de las empresas concesionarias estuvo a cargo de las autoridades municipales en ambos países. No obstante, la similar estructura de los sistemas eléctricos en Argentina y en Brasil, la participación del estado en la regulación de este sector estratégico para el desarrollo económico, se produjo en diferentes coyunturas. Como resultado de la crisis de 1930, el gobierno brasileño transformó los principios jurídicos que reglamentaban la gestión de la electricidad aplicando un criterio de regulación discrecional; mientras que el estado argentino intervino una década más tarde, nacionalizando las empresas. Mediante la comparación de las trayectorias regulatorias en ambos países, se identifican las divergencias en las políticas eléctricas y su impacto en los sistemas eléctricos en los años de la segunda posguerra.