Danfoss VLT AHF 005 Operating Instructions Manual page 15

Paralleling of FC's
If several frequency converters are to be connected to
the harmonic filter, the connection is similar to the
standard connection - The supply terminals L1, L2 and
L3 of several frequency converters must be connected
to the filter module terminals X2.1, X2.2 and X2.3.
NB!
If several FC's are to be connected to the
same filter, the harmonic filter must be
sized according to the sum of the calcula-
ted input current to the FC's.
Paralleling of filters
If the line input current of the frequency converter ex-
ceeds the nominal current of the largest harmonic
filter, several harmonic filters can be paralleled to ach-
ieve the necessary rating. Supply voltage must be
connected to the terminals X1.1, X1.2 and X1.3 of the
filters. The frequency converter supply terminals L1,
L2 and L3 must be connected to the filter modules ter-
minals X2.1, X2.2 and X2.3.
NB!
Filters of different current ratings can be
paralleled. The rating of the filter becomes
the sum of the individual current ratings.
Capacitor disconnect
The power factor of the harmonic filter AHF 005/010 is
decreasing with decreasing load. At zero load the
Power Factor becomes zero and the capacitors pro-
duce approximately 30% leading current compared to
the rated current of the filter. The reactive current gen-
erated by the filter at partial load is normally not of any
concern, mainly because of the small current com-
pared to the system capacity (max 30%) as well as the
fact that other load normally compensates the capac-
itive current.
In applications where this reactive current may not be
accepted, Terminals X3.1, X3.2, X3.3 and X4.1, X4,
14
AHF 005/010
X4.3 are giving acces to the filter capacitors. As default
(on delievery) the wiring will shorten Terminal X3.1
with X4.1, X3.2 with X4.2 and X3.3 with X.4.3. In the
case of that no capacitor disconnect is required no
changes should be made. If capacitor disconnecet is
required a three-phase contactor should be placed be-
tween terminals X3 and X4. Size the contactor and
wiring to 50% of the nominal current and use the AC3
rating of the contactor.
NB!
Only switch the contactor at less than 20%
output power. Allow minimum 240 sec-
onds for the capacitors to discharge be-
fore turning on again.
Use cables complying with local regula-
tions.
®
MG.80.B5.02 - VLT is a registered Danfoss trademark