Keba ServoOne Series, Operation Manual

Page: 30 / 92

Operation Manual ServoOne Supply Unit
30
ID no.: 1101.21B.6-00 Date: 04/2020
4.2.3 Earthing measures
All earthed points and components must be routed directly to the central earthing
point (e.g. PE rail, main earth) with as low an impedance as possible and with good
conductivity. In this way an earthing system is produced that connects all connections to
the earthing point in a star topology. This central earthing point is to be clearly defined.
This earthing point can be extended to the entire backing plate with an effective EMC
connection.
You should take into account the following points for the earthing:
y
Earthed surfaces act as shielding measures and reduce electromagnetic fields
in the surrounding area. For this reason metal surfaces should be connected
to ground with low-impedance HF connections. In terms of EMC it is not the
cross-section of the cable that is definitive, but the surface over which high-
frequency currents (caused by the skin effect) can flow away.
y
Connect the protective earth conductors for the components in the switch
cabinet using a star topology.
y Avoid the use of connectors.
y
Also connect the walls and doors of the switch cabinet to earth.
y Larger openings in the switch cabinet (window, fan, display) degrade the
shielding effect of the cabinet and must be protected with additional shielding
measures for the HF range.
y Earth unused cores at one end so that there is no electrostatic charging.
y
Free contact areas of paint and corrosion and make large area connections.
y The usage of metallised elements is to be preferred over painted components; it
will then not be necessary to remove the paint. The ServoOne supply unit has a
galvanised sheet steel back panel.
y
For further information on the cross-section of the protective earth conductor
see “4.5 Connection of the protective earth conductor”.
4.2 Effective EMC installation
4.2.1 Cable type
y
Use only shielded mains, motor and signal cables as shown in Figure 4.7,
p. 35. For all shielded connections, use cables with double copper braiding
with 60 to 70% coverage.
4.2.2 Routing of cables
You should take into account the following points on laying the cables:
y
Route mains, motor and signal cables separated from one another. Maintain a
distance of at least 200 mm.
y For smaller distances use separators for shielding; fasten the separators directly
and conductively to the backing plate.
y
Route the cables close to ground potential. On the usage of cable ducts made
of plastic, the cable ducts must be fastened directly to the backing plates or the
frame. Open space must not be spanned, as otherwise the cables could act
like antennae.
y Avoid unnecessary cable lengths and "loops of spare cable".
y
Route long cables in places not be susceptible to interference. Otherwise
coupling points may be created.
y
Route motor cables without interruptions (e.g. not via terminals) and lay them by
the shortest route out of the switch cabinet.
y Twist wires for the same electrical circuit.
y
Ideally, route the signal cables separated from encoder cables.
y All signal cables should be combined and routed away upward.
y
Avoid extending cables via terminals.
NOTe:
Please be aware that the supply unit is not designed for electromagnetic
environment class 3 (EN 61000-2-4). Further measures are essential to
achieve this environment class! For further information please consult your
project engineer.
Electrical installation