Active filter

When, after profound analysis, it turns out that the present harmonics not occur in one particular rank/frequency (3^rd, 5^th or 7^th), but are spread over these three and higher ranks, it is suitable to choose for the principle of an active filter.

An active filter reduces the harmonics mainly upstream and partly downstream.

First there is a measurement in three phases downstream.

The filter will measure in that way the pollution that comes from the user(s).

The filter will inject the reverse harmonic in each rank and will neutralize in that way all harmonics in the network.

Consequently the current source will be discharged : other users receive a more stable voltage through a proper sinewave. The user himself receives also a more stable charge.

Since the harmonics are reduced upstream, they can't influence anymore the impedance of the cables and transformer.

Also their influence in the direction of other users/LV ditribution panels is finished.

Active filter for a heavy polluted network without any special applications. 

Active filter for a heavy polluted network with special applications.

• The harmonics in the neutral are filtrated contineously.

     The filtration is realised by an internal reactor without activation of the active filter.

• "Real time" applications : the filter is activated in less then 300µsec.