Application in Explosive Environments • 143
Classification Meeting CENELEC and IEC
WAGO-I/O-SYSTEM 750
DeviceNet
6.3.5 Types of Ignition Protection
Ignition protection defines the special measures to be taken for electrical
components in order to prevent the ignition of surrounding explosive at-
mospheres. For this reason a differentiation is made between the following
types of ignition protection:
Identifi-
cation
CENELEC Standard IEC Stan-
dard
Explanation
Application
EEx o
EN 50 015
IEC 79-6
Oil encapsulation
Zone 1 + 2
EEx p
EN 50 016
IEC 79-2
Overpressure encap-
sulation
Zone 1 + 2
EEx q
EN 50 017
IEC 79-5
Sand encapsulation
Zone 1 + 2
EEx d
EN 50 018
IEC 79-1
Pressure resistant
encapsulation
Zone 1 + 2
EEx e
EN 50 019
IEC 79-7
Increased safety
Zone 1 + 2
EEx m
EN 50 028
IEC 79-18
Cast encapsulation
Zone 1 + 2
EEx i
EN 50 020 (unit)
EN 50 039 (system)
IEC 79-11
Intrinsic safety
Zone 0 + 1 + 2
EEx n
EN 50 021
IEC 79-15
Electrical components
for zone 2 (see below)
Zone 2
Ignition protection “n" describes exclusively the use of explosion protected
electrical components in zone 2. This zone encompasses areas where ex-
plosive atmospheres can only be expected to occur rarely or short-term. It
represents the transition between the area of zone 1, which requires an ex-
plosion protection and safe area in which for instance welding is allowed at
any time.
Regulations covering these electrical components are being prepared on a
world-wide scale. The standard EN 50 021 allows electrical component
manufacturers to obtain certificates from the corresponding authorities for
instance KEMA in the Netherlands or the PTB in Germany, certifying that
the tested components meet the above mentioned standards draft.
Type “n” ignition protection additionally requires electrical components to
be marked with the following extended identification:
•
A – non spark generating (function modules without relay /without
switches)
•
AC – spark generating, contacts protected by seals (function modules
with relays / without switches)
•
L – limited energy (function modules with switch)
Further information
For more detailed information please refer to the national and/or international
standards, directives and regulations!
