Chapter 2—Engineering Considerations
10 DG1 Series VFD MN040002EN—March 2014 www.eaton.com
Electrical Power Network
Input Connection and Configuration
The DG1 Series frequency inverters can be connected and
operated with all control-point grounded AC power networks
(see IEC 60364 for more information).
Figure 5. AC Power Networks with Grounded Neutral
Point (TN- / TT Networks)
The frequency inverter can be applied to all types of power
networks above. If multiple frequency inverters with
single-phase supplies are to be connected, a symmetrical
distribution to the three external conductors shall be taken
into account. In addition, the total current of all single-phase
consumers is not to cause an overload of the neutral
conductor (N-conductor).
The connection and operation of frequency inverters to
asymmetrically grounded TN networks (phase-grounded
delta network “Grounded Delta”, USA) or neutral point
ungrounded or high-resistance grounded (>30 ohms) IT
networks is only conditionally permissible. In these networks
above-mentioned, the internal interference suppression filter
of frequency inverter must be disconnected (unscrew the
screw marked ‘EMC’, see “Installation in IT System” on
Page 43). Then the required filtering for EMC
(electromagnetic compatibility) is no longer present (degrade
to Class T).
Measures for EMC are mandatory in a drive system in order
to meet the legal requirements for EMC and low voltage
regulations.
Good grounding measures are a prerequisite for the effective
insert of further measures such as shielding of filters.
Without respective grounding measures, further steps are
superfluous.
Input Voltage and Frequency
The standardized input voltages (IEC 60038, VDE017-1) for
energy suppliers (EVU) guarantee the following conditions at
the transition points:
●
Deviation from the rated value of voltage: Max. ±10%
●
Deviation in voltage phase balance: Max. ±3%
●
Deviation from rated value of the frequency: Max. ±4%
The board tolerance band of the DG1 frequency
inverter considers the rated value for European as
(EU: ULN = 230V / 400V, 50 Hz) and American as
(USA: U
LN = 240V / 480V, 60 Hz) standard voltages:
●
230V, 50 Hz (EU) and 240V, 60 Hz (USA) at DG1-32_
●
400V, 50 Hz (EU) and 480V, 60 Hz (USA) at DG1-34_
For the bottom voltage value, the permitted voltage drop of
4% in the consumer circuits is also taken into account,
therefore a total of ULN –14%.
●
230V device class (DG1-32_): 208V –15% to 240V +10%
(177V –0% to 264V +0%)
●
400V device class (DG1-34_): 380V –15% to 500V +10%
(323V –0% to 550V +0%)
The permitted frequency range is 50/60 Hz (45 Hz –0% to
66 Hz +0%).
Input Voltage Balance
Due to the uneven loading on the conductor, and with the
direct connection of greater power ratings, deviations from
the ideal voltage form and asymmetrical voltages can be
caused in three-phase AC power networks. These
asymmetric divergences in the input voltage can lead to
different loading of the diodes in input rectifiers with
three-phase supplied frequency inverters, and as a result,
an advance failure of this diode.
In the project planning for the connection of three-phase
supplied frequency inverters, consider only AC power
networks that handle permitted asymmetric divergences in
the input voltage ≤ +3%.
If this condition is not fulfilled, or symmetry at the connection
location is uncertain, the use of an assigned AC choke is
recommended.
L1
L2
L3
N
TT
L1
L2
L3
N
PE
TN-C-S
L1
L2
L3
N
PE
TN-S
L1
L2
L3
PEN
TN-C
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