Schaffner ECOsine, Maintenance Manual

Page: 11 / 66

ECOsine
®
active Harmonic Filters
– Maintenance Manual for FN3420-200-690-3 11
2.1 Principle of operation
The ac mains current, which is drawn by a non-linear load, is measured by ECOsine
®
active
either directly or indirectly via external current transformers. The harmonic content and
reactive power components are detected and processed in a digital control structure. The
active filter continually generates a compensating current that offsets the harmonic content
and reactive current in the load, so the ac mains only has to provide the minimum
fundamental in phase current.
Compensating current
Mains supply
Load
Neutral
Fig. 1: Principle of operation of the ECOsine
®
active filter
The active filter instantly adapts to all changes in the load and the systems harmonic
content spectrum, in order to be able to optimally respond at any time.