Page 612 - Wago_Rail-MountedTerminalBlockSystems_Volume1_2015_US.pdf

14 General Technical Information

610 for Electrical Equipment in Hazardous Areas
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 (protected) equip-
atmosphere. Such an atmosphere can PRINCIPLE FOR EXPLOSION PRO- ment must be used in areas in which
be produced at any location where flam- TECTION: an explosive atmosphere may still be
mable gases or liquids are manufactured, General Provisions expected despite the implementation of
processed, transported and/or stored. European Standard EN 60079-0 – Clas- prevention measures.
Such hazardous environments can be sification VDE 0170, Part 1 – contains Electrical, explosion protected equipment
formed for example in chemical plants, the “General provisions” for the design can have various types of protection in
refineries, power plants, paint producing and testing of electrical equipment to be accordance with the construction specifi-
facilities, painting shops, filling stations, used in hazardous areas. cations of the standards series.
vehicles, sewage treatment plants, air- This ensures this equipment does not Protection used by the manufacturer
ports, grain mills or harbor facilities. cause an explosion in the surrounding essentially depends on the type and func-
atmosphere. tion of the apparatus. From a safety point
EN 60079-0 is supplemented or revised of view, all standardized types of protec-
by the European standards indicated on tion should be viewed as equal.
the right which refer to the specifically The ignition protection category “n”
standardized types of protection. describes exclusively the use of explosion
protected electrical components in Zone
Electrical Equipment 2. This zone includes areas where explo-
Electrical equipment includes all objects sive atmospheres can only be expected
used in whole or in part with electricity. to occur rarely or for short duration.. This
This includes items for generation, trans- represents a transition between Zone 1,
port, distribution, storage, measurement, in which explosion protection is required,
control, conversion and consumption of and the safe area in which, for example,
electrical power, as well as telecommuni- welding may be performed at any time.
cations. Regulations covering these electrical com-
ponents are being prepared worldwide.
Ex Components Organizations such as KEMA in the
Ex components are elements of electrical Netherlands, or PTB in Germany certify
equipment for hazardous areas that are that the devices meet the requirements of
marked with the letter “U”. These com- the EN 60079-15 European standard.
ponents shall not be used on their own The ignition protection category “n” addi-
in such areas and require an additional tionally requires electrical components to
certificate when used in such areas when be marked with the following extended
installed in the electrical equipment. identification:
● A – non-sparking (function modules
without relays/switches)
● AC – sparking, contacts protected with
seals (function modules with relays/
without switches)
● L – limited power (function modules
with switches)
The table on the opposite page shows
an overview of the standardized ignition
protection categories and describes their
basic principle, as well as typical appli-
cations.