Siemens SIROTEC Engineering Manual

Fundamental Principles and System Description
Engineering Information
SINAMICS Engineering Manual – November 2015
Ó Siemens AG
75/528
6-pulse rectifier with line reactor on a three-phase supply
Typical harmonic currents of a 6-pulse rectifier with a line reactor are specified in the following (relative short-circuit
voltage (per unit impedance) of the line reactor = 2 %).
These data are based on three supply system constellations with differences in line inductance or relative short-
circuit power RSC (RSC = Relative Short-Circuit Power in accordance with EN 60146-1-1: Ratio between the short-
circuit power S
K Line
of the supply system and the rated apparent power (fundamental apparent power) S
Converter
of the
converter at its point of common coupling PCC).
a) Supply system with low supply system inductance or high relative short-circuit power (RSC >> 50)
The short-circuit power S
k
Line
at the PCC is significantly higher than the apparent power of the connected
converters, i.e. only a relatively small percentage of the transformer load is attributable to the converter. This is
the case, for example, when a converter with an apparent power of << 100 kVA is connected to a supply system
which is supplied via a transformer with an apparent power of several MVA.
b) Supply system with average supply system inductance or average relative short-circuit power (RSC = 50)
This applies, for example, when approximately 30 % to 50 % of the transformer load is attributable to the
converter.
c) Supply system with high supply system inductance or low relative short-circuit power (RSC < 15)
This is the case when 100 % converter load is connected to a transformer with a high short-circuit voltage, i.e
only one converter whose apparent power approximately corresponds to the apparent power of the transformer.
Supply system with high relative short-circuit power (RSC >> 50): "Strong supply system"
h 1 5 7 11 13 17 19 23 25 THD(I)
I
h
100 % 45.8 % 21.7 % 7.6 % 4.6 % 3.4 % 1.9 % 1.9 % 1.1 % 51.7 %
Supply system with average relative short-circuit power (RSC = 50)
h 1 5 7 11 13 17 19 23 25 THD(I)
I
h
100 % 37.1 % 12.4 % 6.9 % 3.2 % 2.8 % 1.9 % 1.4 % 1.3 % 40.0 %
Supply system with low relative short-circuit power (RSC < 15) "Weak supply system"
h 1 5 7 11 13 17 19 23 25 THD(I)
I
h
100 % 22.4 % 7.0 % 3.1 % 2.5 % 1.3 % 1.0 % 0.8 % 0.7 % 23.8 %
Typical harmonic currents of 6-pulse rectifier with line reactors v
k
= 2 %
Spectral representation of the harmonic currents of a 6-pulse rectifier with line reactor v
k
= 2 % (specified in %)
- Bars on left: RSC >> 50
- Bars in center: RSC = 50
- Bars on right: RSC < 15
0
10
20
30
40
50
60
70
80
90
100
1357 9 11 13 15 17 19 21 23 25

Siemens SIROTEC Specifications

General

Brand	Siemens
Model	SIROTEC
Category	DC Drives
Language	English