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General Technical Information on Electrical Equipment Used in Hazardous Areas 13
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A prerequisite for a potentially explosive THE FOLLOWING APPLY AS A Ignition Protection Categories
hazard is the formation of an explosive GUIDELINE FOR THE UNDERLYING Only explosion-proof equipment must be
atmosphere. Such an atmosphere can PRINCIPLE FOR used in areas where an explosive atmo-
be produced at any location where flam- EXPLOSION PROTECTION: sphere may still be expected despite the
mable gases or liquids are manufactured, implementation of prevention measures.
processed, transported and/or stored. Explosion-proof electrical equipment can
Such hazardous areas can be found - General Provisions have various types of protection in accor-
in a wide range of industries, including European Standard EN 60079-0 – Clas- dance with the construction specifications
chemical plants, refineries, power plants, sification VDE 0170, Part 1 – contains of the relevant standards.
paint producing facilities, painting shops, the “General provisions” for the design
filling stations, vehicles, sewage treatment and testing of electrical equipment to be Protection used by the manufacturer
plants, airports, grain mills or harbor used in hazardous areas. essentially depends on the type and func-
facilities. tion of the apparatus. From a safety point
This ensures this equipment does not of view, all standardized types of protec-
cause an explosion in the surrounding tion should be viewed as equal.
atmosphere. Ignition protection category “n” describes
EN 60079-0 is supplemented or revised exclusively the use of explosion-proof
by the European standards indicated on electrical components in Zone 2. This
the right which refer to the specifically zone includes areas where explosive
standardized types of protection. atmospheres can only be expected to
occur rarely or for short duration. This
Electrical Equipment represents a transition between Zone 1,
Electrical equipment includes all objects in which explosion protection is required,
used in whole or in part with electricity. and the safe area in which, for example,
This includes items for generation, trans- welding may be performed at any time.
port, distribution, storage, measurement,
control, conversion and consumption of Regulations covering these electrical com-
electrical power, as well as telecommuni- ponents are being prepared worldwide.
cations. Organizations such as KEMA in the
Netherlands, or PTB in Germany certify
Ex Components that the devices meet the requirements of
Ex components are elements of electri- the EN60079-15 standard.
cal equipment for potentially explosive Ignition protection category “n” also
areas that are marked with the letter “U”. requires that electrical equipment be
These components may not be used on provided with additional ID markings as
their own in such areas and require an follows:
additional certificate when used in such • A – non-sparking (function modules
areas when installed in the electrical without relays/switches)
equipment. • AC – sparking, contacts protected with
seals (function modules with relays /
without switches)
• L – limited power (function modules
with switches)

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