3 Installation
3.4 Ear thing
56 DC1 variable frequency drive 12/13 MN04020003Z-EN www.eaton.com
3.3.3 Screen earth kit
Unscreened cables behave like antennae, i.e. they act as transmitters and
receivers.
The effectiveness of the cable shielding depends on a good shield connec-
tion and a low shield resistance.
3.4 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 variable frequency drive must be individually connected to the power
supply system's protective earth directly at the location of installation
(system earthing). 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 magnet system's conductive compo-
nents (variable frequency drive, motor choke, motor filter, main choke)
should be connected.
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.
￫
For a proper EMC connection, cables emitting interference
(e.g. motor cables) and susceptible cables (analog signal and
measured values) must be screened and laid separately from
each other.
￫
Use only shields with tinned or nickel-plated copper braiding.
Braided steel shields are unsuitable.
￫
Control and signal lines (analog, digital) should always be
grounded on one end, in the immediate vicinity of the supply
voltage source (PES).
￫
Avoid
ground
loops
when
installing
multiple
variable frequency
drives 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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