Estellito Rangel

A comparative study between copper and aluminum induction squirrel cage constructions

This paper compares different squirrel cage designs under starting and running performance. Inrush current, torque, stall time, maximum number of consecutive starts, efficiency, power factor, critical speed and cage stress are discussed along the paper while considering aluminum and a copper alloy cages. For the sake of comparison two machines were selected to perform the study — one 4-pole 6500 HP and one 18-pole 3500 HP. In addition, procedures of repairing fabricated copper and aluminum cages are discussed.

Directives for offshore service containers

This paper describes the design of assembling a service container to be used safely in offshore oil platforms, even if located in hazardous locations. The task was done after analysis involving the design requirements for offshore installations given by Classification Societies and also by International and Brazilian standards. As complimentary information, the Brazilian legal requirements for certification of electrical equipment designed for hazardous locations are explained in Appendix A. The mechanical structural requirements for transportation and construction of the service container are not included in this study.

Brazil moves from divisions to zones [hazardous location safety]

After decades of using the National Electrical Code/spl reg/ (NEC) and North American standards to classify hazardous locations according to the National Electrical Code/spl reg/ (NEC), Brazil is now starting to use the International Electrotechnical Commission (IEC) standards. Because of these revised directives, the electrical installations and designers of oil and gas industry plants have faced the challenge to harmonize the electrical installations between the NEC and IEC requirements. Considering that the Brazilian Oil and Gas Sector is expected to invest approximately US

Maintenance Strategy for Electrical Equipment Based on Integrated Operations

100 billion in the next ten years, this change will cause a huge impact. Although this paper is mainly focused on the Brazilian market, it discusses very similar difficulties founded by other countries in the same process of changing to IEC. As Brazilian regulations also require National compulsory conformity certification for electrical and electronic. equipment used in hazardous locations, these aspects and installation details are also discussed.

The Importance of Inspections on Electrical Installations in Hazardous Locations

This paper presents a methodology to define a maintenance strategy for electrical equipment, including electric motors. This methodology is based on reliability-centered maintenance, and aims to ensure that the maintenance strategy results in maximum availability and efficiency of equipment and systems. The methodology is also compatible with the philosophy of integrated operations recently developed by the Norwegian petroleum industry to optimize the production from their mature oil fields. The first step is focused on the determination of the equipment criticality value. The paper proposes a methodology based on the Mudge method. Reliability criteria are adopted according to the criticality value. The maintenance intervals are determined considering the reliability criterion and the failure rate of each part of a motor. After determining criticality, the maintenance strategy and tasks are analyzed and determined based on failure modes and failure rates. To support this analysis, a procedure based on failure mode and effect analysis theory is used.

Explosion Risk in Underground Networks: Measures for Preventing Manhole Explosion Events

Electrical installations in hazardous locations (classified areas) need careful attention because non-conformities can bring considerable risks not only to the site, but also for other industries and residential areas nearby. To assure safe operation of an industrial facility it is necessary not only that all electrical and electronic equipment to be used in hazardous locations is correctly specified and purchased (known as “Ex equipment”), but also properly installed and maintained. The discussion in this paper is largely based upon International Electrotechnical Commission (IEC) standards; however, conceptually the same philosophy applies to American based standards and installations as well.

International standards on explosive atmospheres: Harmonization is a hard but necessary task

Manhole explo-sions have occurred in many cities and are concerning to citi-zens. This article cites some man-hole explosion events, shows the measures taken so far by authorities in Rio de Janeiro, analyzes some hypothe-ses for the root causes, and provides some suggestions to solve this dangerous problem.