Estudo de readequação das proteções elétricas de baixa tensão utilizando um relé microprocessado em uma planta siderúrgica

Abstract

The electric engines stand out as the main electrical load in industries and one of the major problems associated with their use is the burning of their windings. For this justification, a plan was developed with the main of readjusting the protections of a Low Voltage Intelligent Motor Command Center (MCC), with the intention of decrease the combustion of motors and breaking equipment coupled in a dedusting unit of a steel plant. In intuition of this context, the present essay proposes to review the main electrical characteristics of three-phase induction motors and control and protection elements and the presentation of a low voltage microprocessor relay, Tesys T from Schneider, since it implements the main motor protection functions. From an analysis of the electric motors, the equipment coupled to it and the outline of the functional units of a low voltage CCMI of an industrial unit, it was possible to identify and present a methodology for adjusting the protections of these motors withal, there is an attempt to identify the principal aspects related to three-phase induction motors, with the following assumptions: the parameters of three-phase induction motors, their main protection and control elements, their main protection functions and the Tesys T intelligent relay. the essay in phases is presented: the data collection of the engines and equipment that compose the CCMI drawers, the definition of the protection settings of the backups of the relays and the monitoring of the implementation and records of the parameters of the adjusted protection functions. Pending these stages, the main problems of the project implementation were identified: current unbalance, where an inadequate condition was identified in the electric plant, equipment with mechanical coupling with wear and Tesys T relays with inadequate range of performance, which compromised performance of protection functions.