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EMC Installation
Note: All following information is strongly recommended
but is not necessary if sufficient system design
and validation has been completed.
The responsibility to meet the local system EMC limit
values and electromagnetic compatibility requirements
is the responsibility of the end user or the system
operator. This operator must also take measures to
minimize or remove emissions in the environment
concerned. He must also use means to increase
the interference immunity of the system devices.
In a drive system (PDS) with frequency inverters, you
should take measures for electromagnetic compatibility
(EMC) while doing your planning, because changes or
improvements to the installation site, which are required
in the installation or while mounting, are normally
associated with additional higher costs.
The technology and system of a frequency inverter
cause the flow of high frequency leakage current during
operation. All grounding measures must therefore be
implemented with low impedance connections over a
large surface area.
With leakage currents greater than 3.5 mA, in
accordance with VDE 0160 or EN 61800-5-1, either
•
the protective conductor must have a cross-
section of at least 10 mm2
•
the protective conductor must be open-circuit
monitored, and the supply must be automatically
disconnected in case of discontinuity of the
protective earthing conductor, or
•
the second protective conductor must be fitted
For an EMC-compliant installation, we recommend the
following measures:
•
Installation of the frequency inverter in a metallic,
electrically conducting enclosure with a good
connection to earth
•
Shielded motor cables (short cable lengths)
•
Ground all conductive components and housings
in a drive system using as short a line as possible
with the greatest possible cross-section (Cu-
braid)
EMC Measures in the control panel
For EMC-compatible installation, connect all metallic
parts of the device and the switching cabinet together
over broad surfaces and so that high-frequencies will be
conducted. Mounting plates and cabinet doors should
make good contact and be connected with short HF-
braided cables. It is recommended to avoid using
painted surfaces (anodized, chromized). An overview of
all EMC measures is provided in the figure on Previous
Page.
Install the frequency inverter as directly as possible
(without spacers) on a metal plate (mounting plate).
Route input and motor cables in the switch cabinet as
close to the ground potential as possible. This is
because free moving cables act as antennas.
When laying HF cables (for example, shielded motor
cables) or suppressed cables (for example, input supply
cables, control circuit and signal cables) in parallel, a
minimum clearance of 11.81 in (300 mm) is
recommended in order to prevent the radiation of
electromagnetic energy. Separate cable routing is also
recommended when large voltage potential differences
are involved. Any necessary crossed cabling between
the control signal and power cables should be
implemented at right angles (90 degrees).
It is recommended to never lay control or signal cables
in the same duct as power cables. Analog signal cables
(measured, reference and correction values) should
be shielded.
Earthing
The ground connection (PE) in the cabinet should be
connected from the input supply to a central earth point
(mounting plate). All protective conductors should be
routed in star formation from this earth point and all
conductive components of the PDS (frequency inverter,
motor reactor, motor filter, main choke) are to be
connected.
Avoid ground loops when installing multiple frequency
inverters in one cabinet. Make sure that all metallic
devices that are to be grounded have a broad area
connection with the mounting plate.
Screen earth kit
Cables that are not shielded work like antennas
(sending, receiving). Make sure that any cables that
may carry disruptive signals (for example, motor cables)
and sensitive cables (analog signal and measurement
values) are shielded apart from one another with EMC-
compatible connections.
The effectiveness of the cable shield depends on a good
shield connection and a low shield impedance.
It is recommended to use only shields with tinned or
nickel-plated copper braiding. Braided steel shields
are unsuitable.
Control and signal lines (analog, digital) should be
grounded on one end, in the immediate vicinity of the
supply voltage source (PES).
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