Proteção de instalações elétricas industriais com o auxílio de planilhas eletrônicas

Abstract

The great demand for electricity is increasing. The projects and requirements of the concessionaires and norms related to the security of the systems are increasing. As a result, the problems generated by the complexity of the installations, such as short circuits and damage to electrical equipment integrated into the electrical system of an industry, for example, can be very serious. For this reason, the development of a quality protection system for electrical systems is an increasing need. The protection of equipment such as circuit breakers, transformers, relays, among others, which over the last few years have advanced technologically, requires increasing studies and care. The automation of this process through software allows the engineer to gain time and confidence when preparing protection studies and projects. Therefore, this work aims to elaborate the automation of the dimensioning of an industrial electrical protection system fed at medium voltage and load above 300 kVA. This situation requires the construction of a protection cabin to feed the consumer. This cabin must have measurement, protection and, optionally, transformation in the same place. The characteristics, types and behavior of the protection, coordination and selectivity equipment of the system are also studied. In addition, the automatic calculation of the expected demand at the point of delivery will be presented, considering different types of motors, lighting demand and other electrical circuits. The automation of protection sizing achieves the objective by obtaining the phase and neutral curves of the relay and presenting the inrush and ANSI current points, circuit rated, neutral and phase starts, and faults. All of this is summarized in a coordination chart that facilitates the analysis and subsequent approval of the project by the concessionaire.