Specifications

32
Schneider Electric
Implementation guidelines (continued)
b Attach unshielded cables in corners of chutes.
b Use a vertical separation in the trunking to avoid mixing incompatible cables.
b Place a metal cover on the signal half of the trunking.
Note: a metal cover over the complete trunking does not improve EMC.
Plan ahead for changes in your installation.
Definition: For each communication network, an initial maximum segment length
without repeater must be respected. This length depends on network speed and the
size of the cable used.
This maximum length, indicated in product documentation, can be attained only if
installation conditions are satisfactory with respect to EMC (cables laid in metal
trunking with end-to-end electrical continuity, connected to the equipotential grid and
earth).
Definition: A maximum theoretical length for electromagnetic compatibility (TLC)
must also be defined. This second restriction is theoretical because it is usually
longer than the first. It is used to optimise installation conditions and should be
respected along with the first limit.
It also applies to a segment with no regenerative repeater.
The theoretical EMC length is 1200 m on average, but can vary according to the type
of communications network:
b 2000 m for FIP at 1 Mbit/s and for Unitelway.
b 1000 m for Modbus Plus and for Ethway tri-axial cable at 50 W.
b 700 m for Mapway.
b 400 m for the BusX system in PREMIUM PLCs.
Likewise, when single trunking is used for power and signal cables, a coefficient
takes into account the absence of a metal separation or metal cover on the portion
of the chute used for signal cables.
E52307E52308
Power or variable
speed drive circuit
Relay circuit
Shielded digital circuit
Shielded analo
g
ue circuit
Unshielded analogue circuit
Unshielded digital circuit
is equivalent to
is equivalent to
E
ff
ectiveness
+
-
Cabling Guidelines