2
INM9370-SS-2
Oct 2010
2 DESCRIPTION
The model numbers given comprise a stainless steel, increased safety, Ex e enclosure
containing one or two carrier-mounted fieldbus barriers. A single barrier module converts
a single, non-intrinsically safe fieldbus trunk into six intrinsically safe (IS) spur connections
for connection to Foundation™ fieldbus H1 fieldbus instruments.
Inside the enclosure, the incoming trunk wiring enters 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.
The spurs are galvanically isolated from the trunk allowing the user to choose the type of
grounding scheme most suitable to their system. Spur short-circuit protection is provided
by the barrier and surge protection can also be added on individual outgoing spurs by
the use of individual Spur Surge protection modules (part no. FS32).
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.
The polished stainless steel enclosures 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. They provide excellent chemical and moisture resistance and are suitable for use
in a wide range of corrosive environments.
The 937x-FB-XX-SS fieldbus barrier enclosures are bus-powered and they 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-Relcom F800 or FPS Series 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 (to EN60529) so the mounting
location should be chosen to comply with this rating.
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) Adequate security should be provided against unauthorised interference.
e) All the necessary gland holes have been prepared in the enclosure. One has a breather
fitted and the others are fitted with appropriate blanking plugs. Where the blanking
plugs are replaced by cable gland, the fitted glands must be Ex e certified and have an
ingress protection (IP) rating that maintains the overall rating of the enclosure.
f) All cable gland holes must be fitted with either a suitable cable gland or blanking
plug.
