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Chapter 3—Engineering considerations
POWERXL SERIES VFDS
MN040060EN—September 2020 www.eaton.com
Chapter 3—Engineering considerations
Introduction
This chapter describes the most important features in the
energy circuit of a drive system that you should take into
consideration in your project planning.
Electrical power network
Input connection and configuration
The PowerXL Series frequency inverters can be connected
and operated with all control-point grounded AC power
networks (see IEC 60364 for more information).
Figure 4. 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 corner-grounded
network and IT System” on page 45). Then the required
filtering for EMC (electromagnetic compatibility) is no longer
present (degrade to level C4).
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%/-15%;
•
Deviation in voltage phase balance: Max. ±3%;
•
Deviation from rated value of the frequency: Max. +/-5 Hz.
The board tolerance band of the PowerXL Series frequency
inverter considers the rated value for:
European as (EU: ULN = 230 V/400 V, 50 Hz);
American as (USA: ULN = 240 V/480 V, 60 Hz); and
Canada as (CAN: ULN = 600 V, 60 Hz) standard voltages:
•
make a direct connection to the input (bypass).
Observe the technical data and connection requirements.
For additional information, refer to the equipment nameplate
or label at the frequency inverter, and the documentation.
Any other usage constitutes improper use.
Input contactor
The input contactor enables an operational switching on
and off the supply voltage for the frequency inverter and
switching off in case of a fault.
The input contactor is designed based on the input current
(ILN) of the frequency inverter and the utilization category
AC-1 (IEC 60947).
While planning the project, make sure that inching operation
is not done via the input contactor of the frequency inverter
on frequency-controlled drives, but through a controller
input of the frequency inverter.
The maximum permitted operating frequency of the input
voltage with the PowerXL frequency inverter is one time per
minute (normal operation).
Total harmonic distortion (THD)
Non-linear consumers (loads) in an AC supply system
produce harmonic voltages that again result in harmonic
currents. These harmonic currents at the inductive and
capacitive reactance’s of a mains supply system produce
additional voltage drops with different values that are
then overlaid on the sinusoidal mains voltage and result in
distortions. In supply systems, this form of “noise” can
give rise to problems in an installation if the sum of the
harmonics exceeds certain limit values.
