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ZONE 2
3
Explosionproof switchgear combinations in
the type of protection 'nR'
(Equipment with built-in components that give
off sparks during normal operation)
The explosionproof switchgear combinations are
intended for use in Zone 2 explosive gas atmo-
spheres according to IEC 60079-0 and IEC
60079-15. IEC 60079-15 'Equipment protection
by the type of protection n' covers explosion-
proof equipment for the equipment protection
level 'Gc' (Zone 2).
The enclosures can be made of stainless steel
(AISI 316L or 304) or stove-enamelled steel. In
addition to a standard range with 16 different
enclosure dimensions, stainless steel enclo-
sures can be made to customer specifications.
All the controlgear combinations that are built
using the standard enclosure range are pre-
pared for wall mounting.
A range of polyester enclosures with 4 compat-
ible dimensions can be joined together by
means of plugged flange connections using a
building block system. The external openings
are fitted with flanges for accommodating cable
glands. If screened cables are installed, brass
flanges with suitable cable glands are available
for the integration of the screening in the equipo-
tential bonding system or for connection to the
protective earth conductor. In addition, the
enclosures can be fitted with covers of different
heights to allow the space-saving installation of
higher components.
Before they are put into operation, restricted
breathing enclosures shall be tested to ensure
the efficacy of the restricted breathing proper-
ties. The test is carried out to determine the time
to change to half the initial pressure value from
3 to 1.5 mbar. This shall not be less than 90 sec-
onds.
Installing explosionproof switchgear (e.g. MCBs,
RCCBs, contactors, thyristors, frequency con-
verters and components) in restricted breathing
enclosures is not permitted. All built-in equip-
ment in the enclosure casing (command
devices, displays, windows) shall meet the
requirements of a standardized type of protec-
tion and the equipment protection level 'Gc'.
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