12
13
INM MTL9373-FB3 Rev 1
INM MTL9373-FB3 Rev 1
In each case the active trunk cable is wired directly to the ‘TRUNK IN’ Fieldbus
Barrier terminals.
The trunk wiring area on the barrier is fitted with a protective plastic cover –
see Figure 5.5. This cover, together with its warning instructions, is intended to
remind the user that working on the trunk connections, without first isolating
the trunk power, is NOT permitted.
IMPORTANT
Cable ferrules must be fitted to any stranded cable or screen wiring that is being used.
Figure 5.5
– Fieldbus Barrier Trunk wiring cover removal.
To remove the trunk wiring cover - First remove the securing screws then press
on the upper edge of the transparent protective cover in the area between the
arrows shown in Figure 5.5 to release the retaining clip, then remove the cover
and move it to the side to obtain access.
Prepare the trunk cable in accordance with the gland manufacturer’s
instructions.
1. Feed the trunk cable through the gland in the enclosure wall and ensure
that any cable armour has a low impedance connection to the enclosure’s
protective local ground.
2. Route the trunk cable through the trunking to provide appropriate
separation from the spur wiring
3. Ensure also that there is sufficient length of cable inside the enclosure to
allow for bends etc. and without causing any strain.
Connect the prepared ends of the incoming fieldbus trunk cable into the +
, – and ‘S’ terminals of the ‘TRUNK IN’ connector – see Figure 5.6 - observing
colour coding in accordance with site wiring regulation.
Figure 5.6
– Fieldbus Barrier Trunk wiring.
If there is no surge suppressor connected into the ‘TRUNK OUT’ terminals
– as in the Figure 5.4 (right) diagram - then a trunk output cable may also be
prepared in a similar manner and connected to the ‘TRUNK OUT’ terminals for
onward connection to an additional enclosure.
• Proceed now to Section 5.5.3 to choose the correct position for the
Trunk Terminator link
5.5 Standard Large Enclosure – Trunk Wiring details
Use this section for guidance if the Standard Large enclosure has been chosen.
The Standard Large Enclosure has more options than the Standard Small as it
can be fitted with additional terminals to marshal and manage unused/spare
trunk cables, and can include Trunk Surge Suppression while also permitting the
use of the Trunk Out terminals. The additional terminals are mounted at the top
of the enclosure on a DIN-rail above the Fieldbus Barrier - see Figure 5.7.
Figure 5.7
– Cutaway examples of Standard Large enclosure showing surge
suppression terminal wiring and terminals for managing spare trunk cable pairs.
