Impacts of Second-, Third-, and Fifth-Order Harmonics on the Thermal Behavior of IE2-, IE3-, and IE4-Class Electric Motors in Grounded Star and Triangle Connections

Electric motors are a widely used equipment capable of transforming electrical energy, consuming a significant part of the electrical energy in industries. With the advancement of technology in recent decades, electric motors have become more efficient and sustainable reaching efficiencies of approximately 96%; however, the presence of electrical power quality disturbances can negatively affect the operation of these machines, increasing their losses and consequently decreasing their efficiency. Based on this context, this work aims to compare the frame thermal variation in IE2-, IE3-, and IE4-class motors, the latter being a line-start permanent magnet motor, connected in grounded star and in triangle under second-, third-, and fifth-order harmonics through 3D thermographic maps obtained from thermographic images. For the measurements, an AC three-phase power supply FCATHQ™ model was used, capable of generating pure sine waves and electrical power quality disturbances of various magnitudes, the data were collected through an infrared camera from the manufacturer FLIR model T620 and the linear load was imposed to the electric motors through a Foucault brake. The three electrical machines analyzed under harmonics are stressed until they reach their thermal equilibrium; the collected data are processed and then analyzed. The results show which harmonic order most impacts on each motor efficiency class, which area of the motor frame is most affected to get a sense of how different harmonic orders impact the internal components and materials of each motor and what is the thermal behavior of each connection for different voltage levels.