Sinus filters have been specially designed to improve the wave form and avoid overvoltages in the motors. These filters are installed in inverters with PWM output, between the converter and the motor. Switching IGBT (isolated gate bipolar transistor) to high frequency causes an output voltage with peaks that can reach 1300 V (or more) in terminals and coils of the motor. These constant voltage values age the motor and decrease the performance of the coils, also wearing and pitting bearings, causing overheating and unnecessary noises and the transmission of interferences through cables. This effect becomes more obvious the greater the distance between the converter and the motor.
It improves the quality of the output wave of the PWM (pulse width modulator), especially in long lines connected to the motor. Reduction of overvoltage peaks caused by PWM and, therefore, a lower wear of motor insulation systems and bearings. Attenuation of the interference emissions radiated by the conductors between the modulator and motor.