Operating instructions

Electrical installation
4.5 EMC-compliant design
Drive converter cabinet units
Operating Instructions, 10/2008, A5E00288214A
53
● If it is impossible to avoid crossing cables, conductors or cables that carry signals of
different classes must cross at right angles, especially if they carry sensitive signals that
are subject to interference.
– Class 1:
unshielded cables for ≤ 60 V DC
unshielded cables for ≤ 25 V AC
shielded analog signal cables
shielded bus and data cables
operator panel interfaces, incremental/absolute encoder lines
– Class 2:
unshielded cables for > 60 V DC and ≤ 230 V DC
unshielded cables for > 25 V AC and ≤ 230 V AC
– Class 3:
unshielded cables for > 230 V AC/DC and ≤ 1000 V AC/DC
Shield connection
● Shields must not be used to conduct electricity. In other words, they must not
simultaneously act as neutral or PE conductors.
● Apply the shield so that it covers the greatest possible surface area. You can use ground
clamps, ground terminals, or ground screw connections.
● Avoid extending the shield to the grounding point using a wire (pigtail) because this will
reduce the effectiveness of the shield by up to 90%.
● Attach the shield to a shield bar directly after the line inlet into the cabinet. Insulate the
entire shielded cable and route the shield up to the device connection, but do not connect
it again.
I/O interfacing
● Create a low-impedance ground connection for additional cabinets, system components,
and distributed devices with the largest possible cross-section (at least 16 mm²).
● Ground unused lines at one end in the cabinet.
● Choose the greatest possible clearance between the power and signal cables (at least 20
cm). The greater the distance over which the cables are routed in parallel, the greater the
clearance must be. If a sufficient clearance cannot be maintained, you must install
additional shields.
● Avoid unnecessarily long cable loops.
Filtering cables
● Line supply cables and power supply cables for devices and modules may have to be
filtered in the cabinet to reduce incoming or outgoing disturbances.
● To reduce emissions, the device is equipped with a radio interference suppression filter
as standard (in accordance with the limit values defined in category C3). Optional filters
can be fitted for use in the first environment (category C2).