2 Engineering
2.2 Electrical power network
DB1 variable frequency drive
11/20 MN040031EN
Eaton.com
35
2.2 Electrical power network
2.2.1 Mains connection and network configuration
The DB1 series of variable frequency drives can be connected to and run on
all star point-grounded AC supply systems (TN-S, TN-C, TT; please refer to
IEC 60364) without any limitations.
Figure 26: AC supply systems with earthed center point
The connection and operation of variable frequency drives to asymmetrically
grounded TN networks (phase-grounded delta network “Grounded Delta”,
USA) or non-grounded or high-resistance grounded (over 30
Ω
) IT networks is
only conditionally permissible (internal radio interference filters).
The DB1 series of variable frequency drives can be connected to an asym-
metrically grounded mains supply or to an IT network (non-grounded, isola-
ted).
In this case, the EMC screws must be removed so that the internal RFI radio
interference filter is switched off.
TN-S
TN-C
TT
￫
While planning the project, consider a symmetrical distribution
to the three main phase conductors, if multiple variable fre-
quency drives with single-phase supplies are to be connected.
The total current of all single phase consumers is not to cause
an overload of the neutral conductor (N-conductor).
￫
Operation on non-grounded networks (IT) requires the use of
suitable insulation-monitoring relays (e.g. pulse-grounded mea-
surement method).
￫
In networks with an earthed phase conductor, the maximum
phase-earth voltage must not exceed 300 V AC.
￫
Measures for electromagnetic compatibility are mandatory in a
power drive system, to meet the legal standards for the EMC-
and Low Voltage Directives.
Good grounding measures are a prerequisite for the effective
use of further measures such as shielding or filters.
Without respective grounding measures, further steps are
superfluous.
L2
N
L1
L3
PE
L2
PEN
L1
L3
L2
N
L1
L3
