Sine wave filters from Schaffner EMC reportedly eliminate premature motor damage caused by high dv/dt, overvoltages, cable ringing, motor overheating and eddy current losses caused by variable frequency drives (VFD). Suitable for motor frequencies up to 600Hz, the technology converts the rectangular PWM output voltage of motor drives into a smooth sine wave with low residual ripple. Sine wave filters can elongate service life of high speed motors and improve bearing life by eliminating circulating bearing currents, according to the company. Typical applications include high-speed spindles, textile machinery, lasers, military appliances (400Hz), HVAC applications, pumps, ventilators, conveyors, compressors, elevators, cranes, step-up transformers, motor drives with multiple motors and motor drives with long motor cables.
A full product line is available to accommodate a wide range of switching kHZ, and voltage ratings up to 690vac. Motor frequency can manage typically 60hz equipment and higher speed 600hz, with application engineered design for even higher frequencies. Model FN5020 and FN5040 Sine wave filters are offered as open and enclosed. Sine wave filters are available for motors up to 200 HP (UL508C) over 200 HP to 800 HP (UL pending). Schaffner says its sine wave filters offer easy installation.