Wednesday, June 20, 2018
Publication Date: 05/1/2008
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EPCOS: New Inverter Motor Filter Technology
SineFormer motor filter.
Iselin, NJ — EPCOS has introduced an inverter output filter technology for frequency converters and drives called SineFormer. In contrast to conventional filter topologies, the SineFormer simultaneously converts the phase-to-phase voltages into sinusoidal Waveforms and minimizes the common mode currents that can damage motor bearings. This technology significantly increases motor operating life by suppressing common mode voltage peaks.

In addition to suppressing harmful voltage peaks, the filter also reduces bearing currents to negligible levels. By doing this, SineFormer is said to practically eliminate EMC problems, and motors protected by the new filter do not require expensive shielded motor cables or special cable ducts.

Even with unshielded cable lengths of 1000m (3,300-ft.), it is possible to comply with the standard EN 55011, Class A-Group 1 and EN 61800-3 Category C2. Installation costs are reduced because unshielded cables are less expensive and are more flexible than shielded cables.

Through the use of unshielded motor cables alone users can realize cost savings beginning with cable lengths of about 100m (330 ft.), depending on current. Moreover, the SineFormer requires neither forced ventilation nor a feedback loop to the converter DC link. The new filter is available for 480VAC motors with rated currents up to 180A and for 575VAC motors with rated currents of 320A. All versions up to 180A are UL/CSA approved.

SineFormer filters are suitable for petrochemical, water and agricultural applications, such as down-hole pumping, dairy farm operations and many other applications involving long motor cable lengths or where motor bearing protection is required.

Contact: EPCOS, Inc., 186 Wood Ave. South, Iselin, NJ 08830. 800-888-7728 or 732-906-4395; fax: 732-632-2830. Web: or

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