Introduction
Operating instructions RHF
25
ELTROPLAN
-
REVCON
Elektrotechnische Anlagen GmbH
4.2 Harmonic line filter for frequency converters
Passive harmonic compensation of the input current of the frequency converter:
The harmonic line filter is used to reduce the circuit harmonic distortions of non
linear loads, which are supplied with uncontrolled B6- bridge rectifiers, how for
example frequency converters. At the REVCON
®
RHF it is about a passive filter
module.
It is not aligned to single frequencies how a absorption circuit, but works how a
Band- stop filter that attenuates strong all low harmonic oscillations approx. until
the fiftieth.
For comparison are in the following chart the circuit harmonic distortions of some
potential circuits in principle represented by means of the THDI (total harmonic
distortion of current) at the rated point of the rectifier:
Rectifier without
chokes
Rectifier with
4% uk
without
chokes
Rectifier
with RHF- A
Rectifier
with RHF- B
Rectifier with RHF- A
and link choke
Rectifier with
RHF-B and link
choke
80 %
40 %
< 16 %
< 10 %
< 10 %
< 5 %
The passive harmonic Rectifier REVCON
®
RHF features an effective, inexpensive
and very efficient (
η
= 99,5%) means, to reduce network loads with harmonics.
Figure 4 shows the typical current waveform of a B6 bridge without RHF module:
Figure 4: The Current waveform without RHF module