The document discusses explosive environment equipment categories and zones. It is divided into groups corresponding to different equipment types and locations where they can be used safely. Group I equipment can function in explosive atmospheres, while Group II equipment has different protection levels for zones 0-2, ensuring safety even if multiple failures occur in zones 0-1 and during normal operation in zone 2. The document also mentions that fieldbus technology allows replacing traditional wiring with a single twisted pair, significantly reducing complexity and costs. PROFINET is provided as an example of a fieldbus standard.

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9. One pair of wires for each device

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Group
Equipment Category
Locations
Corresponds to
Comments
Gases
Dusts
I
M1
Mines
n/a
Capable of functioning safely in the presence of an explosive atmosphere
I
M2
Mines
n/a
Must be de-energised when an explosive atmosphere is present
II
1G
1D
Other
Zone 0
Protection assured in the event of two independent failures
II
2G
2D
Other
Zone 1
Protection assured in the event of foreseeable failures
II
3G
3D
Other
Zone 2
Protection assured during normal operation

15. Source : Wikipedia

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Isolation Barrier

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19. All this wiring could be replaced by a Single Twisted-Pair
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Fieldbus-based

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26. PROFINET
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*
* Above 31.25kb/s

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