Mitsubishi Electric FR-A700 Technical Manual page 479

SELECTION
(e) Active filter
This filter detects the current of a circuit
generating a harmonic current equivalent to
the difference between that current and the
fundamental wave current to suppress the
harmonic current at the detection point.
As this filter compensates for a whole
waveform, a single filter can provide effects on
more than one degree of harmonic.
The filter has a protective function. Therefore,
if there is an incoming excessive harmonic
current, the filter may be short of the harmonic
current absorbing effect (i.e. not perform as
good) but will not overheat or burn out.
To utilize the performance of the active filter
effective, circuit conditions and others must be
examined before installing the active filter.
* For further information, refer to the Technical
note No.28
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