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Bosch Rexroth AG
EMC Measures for Design and Installation
Metal Surfaces
Ground Wires and Shield Connec‐
6.4
Installing Signal Lines and Signal Cables
Line Routing
Shielding
nection points, remove the lacquer so that there is safe electrical contact over
a large surface area. You achieve contact over a large surface area by
means of bare connection surfaces or several connection screws. For screw
connections, you can establish the contact to lacquered surfaces by using
tooth lock washers.
Always use connection elements (screws, nuts, plain washers) with good
electroconductive surface.
Bare zinc-coated or tinned metal surfaces have good electroconductive prop‐
erties.
Anodized, yellow chromatized, black gunmetal finish or lacquered metal sur‐
faces have bad electroconductive properties.
For connecting ground wires and shield connections, it is not the cross sec‐
tions
tion but the size of contact surface that is important, as the high-frequency in‐
terference currents mainly flow on the surface of the conductor.
Always connect cable shields, especially shields of the motor power cables,
to ground potential over a large surface area.
For measures to prevent interference, see the Project Planning Manuals of
the respective device. In addition, we recommend the following measures:
●
Route signal and control lines separately from the power cables with a
minimum distance of d5 = 100 mm (see
(Zones), page
way is to route them in separate cable ducts. If possible, lead signal
lines into the control cabinet at one point only.
●
If signal lines are crossing power cables, route them in an angle of 90°
in order to avoid interference injection.
●
Ground spare cables, that are not used and have been connected, at
least at both ends so that they do not have any antenna effect.
●
Avoid unnecessary line lengths.
●
Run cables as close as possible to grounded metal surfaces (reference
potential). The ideal solution are closed, grounded cable ducts or metal
pipes which, however, is only obligatory for high requirements (sensitive
instrument leads).
●
Avoid suspended lines or lines routed along synthetic carriers, because
they are functioning like reception antennas (noise immunity) and like
transmitting antennas (emission of interference). Exceptional cases are
flexible cable tracks over short distances of a maximum of 5 m.
Connect the cable shield immediately at the devices in the shortest and most
direct possible way and over the largest possible surface area.
Connect the shield of analog signal lines at one end over a large surface
area, normally in the control cabinet at the analog device. Make sure the con‐
nection to ground/housing is short and over a large surface area.
Connect the shield of digital signal lines at both ends over a large surface
area and in short form. In the case of potential differences between beginning
and end of the line, run an additional bonding conductor in parallel. This pre‐
vents compensating current from flowing via the shield. The guide value for
the cross section is 10 mm
You absolutely have to equip separable connections with connectors with
grounded metal housing.
DOK-INDRV*-KCU01******-IT01-EN-P
Rexroth IndraDrive Mi Electronic Control System KCU01
46) or with a grounded separating sheet. The optimum
2
.
6.2.2 Division Into Areas
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