3 Installation
3.3 EMC installat ion
DC1 Frequency Inverter 10/12 MN04020003Z-EN www.eaton.com 59
3.3.2 Earthing
The protective earth (PE) in the control panel should be connected from the
mains supply to a central earth point (mounting plate, system earth). The PE
conductor’s cross-sectional area must be at least as large as that of the
incoming mains supply cable.
Every frequency inverter must be individually connected to the power supply
system's protective earth directly at the location of installation (system earth-
ing). This protective earth must not pass through any other devices.
All protective conductors should be routed in a star topology starting from
the central earth point, and all of the drive system’s conductive components
(frequency inverter, motor reactor, motor filter, main choke) should be con-
nected.
The earth-fault loop impedance must comply with all locally applicable indus-
trial safety regulations. In order to meet UL requirements, UL-listed ring
cable lugs must be used for all earth wiring connections.
3.3.2.1 Protective earth
This refers to the legally required protective earth for a frequency inverter.
An earthing terminal on the frequency inverter, or the system earth, must be
connected to a neighboring steel element in the building (beam, ceiling joist),
an earth electrode in the ground, or a mains earth bus. The earth points must
meet the requirements set forth by the applicable national and local industrial
safety regulations and/or regulations for electrical systems.
￫
When laying HF cables (e.g. screened motor cables) or sup-
pressed cables (e.g. mains supply cables, control circuit and sig-
nal cables) in parallel, a minimum clearance of 300 mm should
be ensured in order to prevent the radiation of electromagnetic
energy. You should also use separate cable entries if there is a
great difference in voltage potentials. Any necessary crossed
cabling between the control signal and power cables should
always be implemented at right angles (90 degrees).
￫
Never lay control- or signal cables in the same duct as power
cables. Analog signal cables (measured, reference and correc-
tion values) must be screened.
￫
Avoid
ground
loops
when
installing
multiple
frequency inverters
in one control panel. Make sure that all metallic devices that
are
to be grounded have a broad area connection with the mounting
plate.
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