Instruction manual

5
INM9380-RD-1
May 2012
After mounting the assembly
Check that:
• none of the component parts have suffered any damage,
• the baseplate of the assembly is not distorted
• the mounting bolts/nuts are all tightened as recommended above.
4 INITIAL ELECTRICAL INSTALLATION
WARNING!
Before starting any electrical installation work, ensure that the
incoming trunk connection is isolated from any source of power.
CAUTION
Assembly temperatures could rise to 75°C. Ensure that all cables and cable
glands fitted are rated to withstand these temperatures.
4.1 Overview
• The assembly receives power from the incoming trunk cable and requires no further
source of power.
• It shall only be powered from supplies conforming to IEC 61158.
• The environment/enclosure in which an assembly is mounted must
ensure adequate separation of the trunk and spur wiring. This may
be provided by means of separate cable trunking or clear physical separation as
defined by local rules. Blue cable trunking is recommended for the IS spur cables
to identify that they are intrinsically safe circuits, while grey or black trunking is
recommended for the non-IS trunk cables. The cable routing should ensure that trunk
and spur cables do not cross each other inside the enclosure.
• Type ‘A’ fieldbus cable is recommended for fieldbus trunk connections.
• The TTA can accommodate trunk cables with outer diameters between approximately
5 and 13mm - see Section 4.3.1 for further details regarding protection rating.
• The terminal blocks for the trunk fieldbus cables have either screw terminal connectors
or cage clamp connectors according to the model specified, but both are suitable for
cables from 0.5mm
2
/AWG 20 up to 2.5mm
2
/AWG 14.
For details of the wiring for the two system types see Appendix 1.
4.2 Grounding
Two distinct ground concepts should be recognised before wiring of the assembly begins:
a) Protective local ground - mandatory
b) Cable shield ground
These two concepts and their implementation are explained below.
4.2.1 Protective local ground
This ground connection is required to ensure that any exposed metalwork of the
assembly does not present a hazard to personnel; it also provides a low impedance
earth grounding circuit for any surge protection items used on the assembly. An M10
earth-grounding stud is provided on the assembly baseplate, which must be bonded to
the body of any protective enclosure and from there to the local plant structure.
Where multiple assemblies are installed inside one final enclosure, the grounding studs
for the individual baseplate must be connected in a “star” formation to the grounding
point on the enclosure.
Note: It is important to prevent these connections from loosening and also to protect
them from corrosion against the stainless steel grounding stud.