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With leakage currents greater than 3.5 mA, in
accordance with VDE 0160 or EN 61800-5-1, either
•
the protective earthing conductor must have a
cross-section of at least 10 mm2 Cu
•
the protective earthing 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 earthing 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 below.
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.
Note:
The shielded cables need to be grounded
according to section “Screen earth kit” to grounding.
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).
