MTL 9312-FB-ST-SS-SP, Инструкция по эксплуатации, Страница: 14 / 24

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INM9312-FB-ST-SS-1 Oct 2008
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8.5 Earthing / Grounding
The 9312-FB-ST-SS-SP Fieldbus Barrier incorporates galvanically isolated safety barriers for the spur
wiring, so an intrinsic safety earth connection is not required.
A number of options for grounding cable screens is available on the 9312-FB-ST-SS-SP barrier, including
‘capacitive’ and direct grounding.
Option 1 - Single point of grounding; trunk and spur shields interconnected
In many installation, the preferred method of grounding is to ground the fieldbus cables at one point
only, normally at the fieldbus power supply. In this case, the trunk and spur cable shields are connected
to each other at the Fieldbus Barrier and are not connected to ground in the field. Cable connections to
the Fieldbus Barrier should then be as shown above in Figure 10.
Note: In order to maintain a single point of grounding, neither the Fieldbus Barrier module nor the
cable shield earth bar should be connected to an external ground. For the 9312-FB-ST-SS-SP Fieldbus
Barrier, the grounding stud (1) is
not connected to the enclosure body. The earth cable (2) is supplied
pre-assembled into the enclosure, but this does not connect the shields of the trunk and spur cables to
ground.
Figure 10: Trunk and spur cable shields to earth bus bar