INM 9370-RD Rev 5
5
Consequently, if a spur ‘fail-over’ occurs, an alarm is signalled quickly to the host,
via the fieldbus connection, to facilitate any necessary remedial action. The five
remaining spurs are available to the user for connection to field devices.
Note
: A
redundant-capable
version of the 9372-FB-Px-yy can also be supplied,
part-populated with a single 6-spur module (order as model number 937
5
-FB-Px-
yy). This permits a future upgrading from the simplex mode to a redundant mode
simply by plugging in an additional Fieldbus Barrier module - and the optional alarm
module, if required.
2.3 Trunk Terminal Assembly
The incoming trunk wiring is terminated inside a separate compartment, called the
Trunk Terminal Assembly (TTA), that contains increased safety (Ex e) trunk wiring
terminals. This assembly has a protective cover to deter interference, and carries a
warning to the user about working on trunk wiring without first isolating the power.
A fieldbus Terminator module (part no. 9378-FT) is supplied pre-fitted on the TTA. This
is to remain installed if the enclosure is at the end of the segment. If the incoming
fieldbus trunk will be onward linked to a further node on the segment the terminator
can be removed. See Section 4.4 on page 13 for additional information.
An optional Trunk Surge module (part no. 9376-SP) can be plugged into the TTA to
protect the fieldbus barrier against damaging voltage and current surges on the
incoming trunk wiring.
Either enclosure may be installed in a Zone 1 or Zone 2 hazardous area; in which
case, the trunk wiring must be implemented using suitably protected cable. The
enclosures provide excellent chemical and moisture resistance and are suitable for
use in a wide range of corrosive environments.
The 9372-FB-Px-yy and 9375-FB-Px-yy Fieldbus Barrier enclosures are bus-powered
and require no additional power supply in the field. When used with a fieldbus host
control system, power for the trunk MUST be provided only by a supply conforming
to IEC 61158-2, e.g. MTL F800 or 918x range of redundant power supplies. The
enclosures are supplied pre–drilled for all trunk and spur cable entries and fitted
with Ex e certified blanking plugs and a breather.
3
MECHANICAL INSTALLATION
See Figures 3.1 and 3.2 for the dimensions, fixing locations and cable gland
positions for both enclosure models.
3.1 Mounting overview
Before mounting an enclosure, consider the following points.
a) The permitted ambient temperature range external to the enclosure (–40°C to
+70°C) must not be exceeded. Avoid radiant heat by locating the enclosure away
from direct sunlight or local sources of heat.
b) The enclosure has an ingress protection rating of IP65 or IP66 (to EN60529)
depending on the manufacturing date. The mounting location should be chosen
to comply with the rating of the enclosure.
c) The enclosure is designed for mounting on a vertical surface, with the cable
entry at the lowest point, as shown in the upper part of Figure 3.1 or Figure 3.2.
d) The nominal weight of the individual enclosures, including two barrier modules,
but excluding any surge protection modules (trunk or spur) is:
Model type
Nominal weight
Stainless steel enclosure
8.0 kg
GRP enclosure
7.8 kg
e) Adequate security should be provided against unauthorised interference.
