Monitoring and Detection of High Resistance Connection in Induction Motor Circuits

High Resistance Connections - HRC - is an important failure that can affect any industrial electrical circuit over time. This problem affects, in particular, the supply circuits of induction motors, which can lead to several other problems in the motor and in the supply circuit itself, such as overheating, fire and damage to components, posing a danger to facilities and people. Given that, in industrialized countries, around 50 % of energy is consumed by electric motors, this problem is worth studying. With the aim of contributing to the resolution of this problem, this work proposes a strategy that makes it possible the early detection of this type of failure. The method is based on the stator current and the zero-sequence component of the stator voltage measured at the center point of the motor winding. The influence of saturation harmonics of the motor powered directly from the electrical grid is evaluated. Simulation and experimental results are presented and show the ability of the technique to predictively monitor the motor circuit.