Desenvolvimento de um dispositivo de proteção contra corrente desbalanceada em motores de indução trifásicos.

Three-phase induction motors are widely used in most industrial processes and are considered one of the main assets of companies. Thus, in order for it to work well and have a longer useful life, it is necessary that it is protected against any type of failure that can lead to improper behavior or unexpected stop, and even irreversible damage. One of the most common problems of these motors is the electric current unbalance, which limits their useful life, which can cause deterioration of the insulation of their coils and, depending on the intensity of the unbalance, the burning of the motor. This damage occurs due to the increase in electrical current in the windings which, in turn, can be a consequence of a voltage unbalance or phase loss. Currently on the market, there are a few electric motor protection devices. As an example, phase loss relays are mentioned, however, due to their operating principle and the characteristic of the electrical voltage, they are not able to identify faults after the point where they are installed. In this way, from the point of installation, the relay will not be able to identify any phase loss. Therefore, this work proposes the development of an electronic protection device, based on the principle that the current in a series circuit is equal in any part of this circuit, that is, regardless of the location of installation of the device in the power circuit, there will be the detection of current unbalance or phase loss. The developed device obtained the expected results, managing to cease the operation of the engine at the time of the failures applied throughout the tests and these will be presented during the development of this Final Paper.