14
15
INM MTL9373-FB3 Rev 1
INM MTL9373-FB3 Rev 1
5.5.1 Active trunk cable wiring
As stated above, the Standard Large enclosure has provision for additional
terminals to manage both trunk surge suppression wiring and additional (spare)
trunk cabling – see Section 5.5.2 for details of the spare cable management.
On this enclosure, the surge suppressor is wired into the extra DIN-rail
terminals, leaving the TRUNK OUT terminals on the Fieldbus Barrier vacant for
onward linking, where necessary.
As seen in Figure 5.7, the DIN-rail terminals are fitted with their own protective
cover, that meets an IP30 ingress protection rating. The cover is lifted off
for access and MUST be replaced upon completion of the work because the
circuits are not intrinsically safe. Pay attention to the warning label on the cover:
WARNING!
DO NOT REMOVE COVER WHILE CIRCUIT IS LIVE IF
FLAMMABLE OR COMBUSIBLE ATMOSPHERE IS PRESENT”
IMPORTANT
Cable ferrules must be fitted to any stranded cable or screen wiring that is being used.
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 incoming trunk cable through the cable trunking provided
3. Connect the active trunk cable as follows.
Figure 5.8
– Connections for active Trunk In
If trunk surge protection is not requested, and the terminals shown in Figure
5.8 are not available, connect the incoming active trunk cable to the Fieldbus
Barrier as illustrated in Figure 5.6 previously.
Trunk –
Trunk +
Trunk ‘S’
5.5.2 Spare trunk cable management
NOTE
If the trunk cable entering the enclosure has no spare wires requiring
management, ignore this section and move on to Section 5.5.3
The Standard Large enclosure may be ordered with additional terminals to
manage multi-core cables where only one cable pair is used for the active trunk
circuit. These spare pairs may require only to be managed in a convenient way,
or they may be an element of the system design enabling a spare pair to be
brought quickly into service in the event of a cable fault occurring.
As tabled above, the terminal options available when ordering are:
a) Sufficient terminals for TWO spare cables,
b) Sufficient terminals for FOUR spare cables.
The options are illustrated below (without any trunk surge suppressor
connections, for clarity).
Figure 5.9
– Spare trunk cable terminals – TWO spares (left)
and FOUR spares (right)
As shown in Figure 5.9, the terminals are fitted with their own protective cover,
that meets an IP30 ingress protection rating. Lift off the cover for access. The
cover MUST be replaced upon completion of the work because the circuits are
not intrinsically safe. Pay attention to the warning label on the cover:
WARNING!
DO NOT REMOVE COVER WHILE CIRCUIT IS LIVE IF FLAMMABLE OR
COMBUSIBLE ATMOSPHERE IS PRESENT”
All of the terminals are electrically ‘floating’. They are not connected to ground
within the enclosure, nor are they connected to each other or to any other circuit.
IMPORTANT
Cable ferrules must be fitted to any stranded cable or screen wiring that is being used.
1. Route the incoming multi-core trunk cable through the cable
trunking provided
2. Prepare the spare cable pairs in the same manner as the active pair and
connect the spare + , – and screen wires on the terminals provided.
3. An additional terminal is provided to enable an overall cable screen
to be terminated.
