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发表于 2012-6-12 21:18
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来自: 中国辽宁
yu0580 发表于 2012-6-12 20:17
谢谢!谢谢!
CCS:
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DNV:
206 Intrinsically safe circuit wiring and termination
a) Cables for intrinsically safe circuits shall have a common
metallic screen or braiding. Multicore cables for Ex-i circuits
shall have individual screened pairs unless all of the
following is complied with:
— the cable shall be installed as fixed installation i.e.
mechanically protected
— the circuit voltage shall be less than 60 V
— the cable shall be type approved or case by case
approved.
b) The outer protection, i.e.braiding, armour or screen of
intrinsically safe circuits shall be connected to the local
earth at both ends, and might also be earthed at intermediate
junction boxes or panels where relevant.
c) Single pair or multi pair cable, having inner screen should
be connected to earth at the safe space or at the barrier end
only. At the hazardous end the screen shall be properly
insulated or terminated. If there is special reason to connect
the inner screen to earth at both ends, then this might
be accepted based on the explanation in IEC 60079-14 sec.
12.2.2.3.
d) Where the installation has separate earth bars for protective
earth, instrument earth and intrinsically safe earth,
these bars shall be used accordingly.
e) Terminals for intrinsically safe circuits and terminals for
non-intrinsically safe circuits shall be separated by a physical
distance of 50 mm or a separating panel. Terminals for
intrinsically safe circuits shall be marked as such.
f) Category Ex-ia- circuits intended for zone 0, and category
Ex-ib-circuits shall not be run in the same cable.
g) Intrinsically safe circuits and non-intrinsically safe circuits
shall not be carried in the same cable.
h) Intrinsically safe cables and non-intrinsically safe cables
shall not be laid together in same cable bunch or pipe.
i) Inside cabinets, screened wiring of non-intrinsically safe
circuits can be laid in the same channel or tray as screened
intrinsically safe circuits. Unscreened conductors in intrinsically
safe and non-intrinsically safe circuits do not need
any separating distance provided that the parallel wiring
length is below 1m, and that the intrinsically safe and nonintrinsically
safe conductors are not laid in the same cable
or wiring bundle or wiring channel. For lengths longer
than 1 m, the conductors shall be run at least 50 mm apart,
or with an earthed metallic partition between the conductors.
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