Previsão de cavitação em bombas com base na estimação do torque da carga por meio da assinatura elétrica do motor de indução

Abstract

In fluid (oil and oil by-products) transportation between refineries and terminals, as well as for industrial plant processes, pumps are used to move the fluids. With the importance of the operational continuity of these pumps, early failure detection and prevention becomes increasingly relevant in order to avoid production losses and decrease maintenance costs. One of the failures of greater destructive impact on centrifugal pumps is cavitation, a phenomenon in which the pressure is reduced to the value of the vapor pressure of the liquid at the operating temperature. Among the existing methods for the detection of this phenomenon is the Load Torque Signature Analysis Method (LTSA). This method uses spectral analysis of the torque developed by the load, obtained from the electrical signals of the motor and the mechanical speed, and based on the relationship between load mechanical failures and their natural frequencies. In this context, the present work aims at the application of sensorless speed estimation methods for induction motors, based on the machine model and electrical signals, in order to estimate the load torque. If feasible, this application allows the use of the LTSA method for the determination of the cavitation phenomenon in centrifugal pumps driven by induction motors without speed control and without the installation of a position or a speed sensor.