Trunk Connections - Eaton 9372-FB-P Series Instruction Manual

Note: After configuring the required grounding option, tighten all screw terminals to
a recommended torque of 0.6 Nm.
4.2.3 Permitted enclosure combinations
The maximum number of redundant intrinsically safe spurs that can be supported
on a trunk segment is 12. The permitted enclosure combinations are shown in Figure
4.3.
Note that a fieldbus trunk terminator (9378-FT) must be fitted (see Section 4.4) to the
last/furthest enclosure on the segment. See also Figure 4.6.
4.3

Trunk connections

Each enclosure is provided with two access holes for trunk glands; one for the
incoming trunk and another for onward linking to an additional enclosure, if
necessary.
4.3.1 Trunk Terminal Assembly
Inside the enclosure, the trunk cables are terminated in a Trunk Terminal Assembly
(TTA). This is a sub-enclosure with a protective lid, secured with a single screw. This
assembly, together with its warning label, is intended to deter a user from working
on the trunk connections without isolating trunk power. See Figure 4.4.
Trunk cables enter via glands, through the enclosure wall shown at the bottom of
the diagram, and the grounding stud is accessible on the lower left side. The trunk
terminal connectors are in the middle of the assembly to receive the trunk wiring.
Terminals are provided to allow a variety of wiring arrangements, according to the
particular requirements of the installation:
– "Trunk In" cable only
– "Trunk In" and "Trunk Out" cables
– Active and spare "Trunk In" cables
– Active and spare "Trunk In" cables with overall cable shield
– Active and spare "Trunk In" cables and "Trunk Out" cable
The '+' and '–' wires of a 'spare' trunk in cable must be connected only to terminals
marked 'NC' . This ensures that the spare cable is not electrically connected in parallel
with the 'active' trunk in or trunk out cables. The cable shield of the spare cable
should be connected to an 'S' terminal.
All 'spare' trunk-in connections ('+', '–' and shield) must be firmly grounded at the
host.
4.3.2 Trunk cable wiring
Cable ferrules should be fitted to all multi-stranded cables being terminated in the
TTA.
Connect the trunk cable(s) in the following way.
a) Loosen the captive screw of the transparent protective cover on the TTA. Slide
out the cover and move it to one side to obtain access.
b) Prepare the trunk cable(s) in accordance with the gland manufacturer's
instructions and feed the cable(s) through the gland(s).
c) Connect the prepared ends of the fieldbus trunk cable(s) into the appropriate '+'
, '–' and 'S' terminals, shown in Figure 4.5, and tighten the screw terminals to a
recommended torque of 0.6 Nm.
INM 9370-RD Rev 5
No part of the Trunk Terminal Assembly may be worked while the
enclosure is powered, unless the environment is known to be non-
hazardous.
CAUTION
WARNING!
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