VSD filter

The Schaffner FN 530 combination sine wave/EMC output filter for variable speed drives solves three important problems for motors as loads for variable speed drives. These are: high dv/dt pulses, common mode high-frequency components and RF radiation.

High dv/dt pulses, if not smoothed by effective filtering, can damage motor and drive cable insulation by building up voltage stress through reflection of voltage pulses. Common mode high-frequency components, due to high-frequency switching IGBTs in the drive inverter stage, flow through the motor frame to earth, damaging bearings in the process. RF radiation also results if high-frequency components are not filtered out and can create interference with other systems or be conducted back to the input of the drive.

The effectiveness of the Schaffner FN 530 filter means that it is possible to use long drive cables up to 1000 m in length, even without shielding, thus providing an economical solution to applications including long conveyor belt systems, tank farms, pump stations and large numbers of motors in parallel.

The Schaffner FN 530 filters provide traditional L-C sine wave filtering, in combination with common-mode (Y) and symmetrical (X) mode EMC filtering, and reduce protective earth current contributions by feeding common-mode components back to the drive’s DC link.

The Schaffner FN 530 filters are suitable for three-phase operation at line voltages to 500 V and current ratings are available from 4 to 16 A.