Danfoss VLT HVAC Basic Drive FC 101, Руководство по конструкции

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2.8.3 General Aspects of Harmonics
Emission
A frequency converter takes up a non-sinusoidal current
from mains, which increases the input current I
RMS
. A non-
sinusoidal current is transformed by means of a Fourier
analysis and split up into sine-wave currents with different
frequencies, i.e. different harmonic currents I
n
with 50 Hz
as the basic frequency:
I
1
I
5
I
7
Hz 50 250 350
Table 2.13 Harmonic Currents
The harmonics do not affect the power consumption
directly but increase the heat losses in the installation
(transformer, cables). Consequently, in plants with a high
percentage of rectifier load, maintain harmonic currents at
a low level to avoid overload of the transformer and high
temperature in the cables.
175HA034.10
Illustration 2.24 Harmonic Currents
NOTICE
Some of the harmonic currents might disturb communi-
cation equipment connected to the same transformer or
cause resonance in connection with power-factor
correction batteries.
To ensure low harmonic currents, the frequency converter
is equipped with intermediate circuit coils as standard. This
normally reduces the input current I
RMS
by 40%.
The voltage distortion on the mains supply voltage
depends on the size of the harmonic currents multiplied
by the mains impedance for the frequency in question.
The total voltage distortion THD is calculated on the basis
of the individual voltage harmonics using this formula:
THD % = U 25 + U
2
7 + ... + U
2
N
(U
N
% of U)
2.8.4 Harmonics Emission Requirements
Equipment connected to the public supply network
Options Definition
1 IEC/EN 61000-3-2 Class A for 3-phase balanced
equipment (for professional equipment only up to 1
kW total power).
2 IEC/EN 61000-3-12 Equipment 16 A-75 A and profes-
sional equipment as from 1 kW up to 16 A phase
current.
Table 2.14 Connected Equipment
2.8.5 Harmonics Test Results (Emission)
Power sizes up to PK75 in T4 and P3K7 in T2 complies with
IEC/EN 61000-3-2 Class A. Power sizes from P1K1 and up to
P18K in T2 and up to P90K in T4 complies with IEC/EN
61000-3-12, Table 4.
Individual Harmonic Current I
n
/I
1
(%)
I
5
I
7
I
11
I
13
Actual 0.25-11
kW, IP20, 200 V
(typical)
32.6 16.6 8.0 6.0
Limit for R
sce
≥
120 40 25 15 10
Harmonic current distortion factor (%)
THD PWHD
Actual 0.25-11
kW, 200 V
(typical)
39 41.4
Limit for R
sce
≥
120 48 46
Table 2.15 Harmonic Current 0.25-11 kW, 200 V
Individual Harmonic Current I
n
/I
1
(%)
I
5
I
7
I
11
I
13
Actual 0.37-22
kW, IP20,
380-480 V
(typical)
36.7 20.8 7.6 6.4
Limit for R
sce
≥
120 40 25 15 10
Harmonic current distortion factor (%)
THD PWHD
Actual 0.37-22
kW, 380-480 V
(typical)
44.4 40.8
Limit for R
sce
≥
120 48 46
Table 2.16 Harmonic Current 0.37-22 kW, 380-480 V
Product Overview
VLT
®
HVAC Basic Drive FC 101 Design Guide
MG18C502 - Rev. 2013-09-06 35
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