VLT
®
8000 AQUA
All about VLT 8000
AQUA
it is important to maintain harmonic currents at
a low level to avoid overload of the transformer
and high temperature in the cables.
Harmonic currents compared to the RMS input current:
Input current
I
RMS
1.0
I
1
0.9
I
5
0.4
I
7
0.3
I
11-49
<0.1
To ensure low, harmonic currents, VLT 8000
AQUA has intermediate circuit coils as standard.
This normally reduces the input current I
RMS
by
40%, down to 40-45% ThiD.
In some cases, there is a need for further suppression
(e.g. retrofit with AFDs). For this purpose Danfoss
can offer two acvanced harmonic filters AHF05 and
AHF10, bringing the harmonic current down to around
5% and 10% respectively. For further details, see the
operating instructions MG.80.BX.YY. For calculation of
harmonic, Danfoss offers the software tool MCT31.
Some of the harmonic currents might disturb
communication equipment connected to the same
transformer or cause resonance in connection
with power-factor correction batteries. VLT
8000 AQUA has been designed in accordance
with the following standards:
- IEC 1000-3-2
- IEEE 519-1992
- IEC 22G/WG4
- EN 50178
- VDE 160, 5.3.1.1.2
The voltage distortion on the line supply depends
on the size of the harmonic currents multiplied by
the line impedance for the frequency in question.
The total voltage distortion THD is calculated
on the basis of the individual voltage harmonics
using the following formula:
■
Power factor
The power factor is the relation between I
1
and I
RMS
.
The power factor for 3-phase control
The power factor indicates the extent to which the
AFD imposes a load on the line supply.
The lower the power factor, the higher the I
RMS
for the same HP performance.
In addition, a high power factor indicates that the
different harmonic currents are low.
MG.80.A7.22 - VLT is a registered Danfoss trademark
185
Rosewood STP ST42 General (Operation and Maintenance Manual - Part 4:
Section 6.3 Manufacturers Manuals 6.3.33 Danfoss VLT Aquadrive 8000) Vendor Manual
QP Id: VM207
Active: 03/09/2013
Page 191 of 208