2 Engineering
2.2 Electrical power network
DC1 Variable Frequency Drive 04/16 MN04020003Z-EN www.eaton.com 37
2.2 Electrical power network
2.2.1 Mains terminal and configuration
DC1 variable frequency drives can be connected to and run on all neutral
point-grounded AC supply systems (TN-S, TN-C, TT grounding systems;
please refer to IEC 60364) without any limitations.
Figure 14: 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 ) IT networks is
only conditionally permissible (internal radio interference suppression filters).
DC1-…-A20N variable frequency drives can be connected to corner-
grounded systems or IT grounding systems (not grounded, insulated).
When versions featuring an internal radio interference suppression filter
(DC1-…FN-A20N, DC1-…FB-A20N) are connected to one of these systems,
the EMC screw(s) needs to be removed and the internal radio interference
suppression filter needs to be disconnected
TN-S TN-C TT
￫
While planning the project, consider a symmetrical distribution
to the three main phase conductors, if multiple variable
frequency 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-earthed networks (IT) requires the use of
suitable insulation monitoring relays (e.g. pulse-code
measurement 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 EMC- and
Low Voltage Directive. Good earthing measures are a
prerequisite for the effective Use of further measures such as
screen earth kit or filters here. Without respective grounding
measures, further steps are superfluous.
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