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9 Glossary
9.1 User Classes (AK)
The classification of units into user classes denotes the safety levels of the unit. The user classes
3 to 5 of the units which are relevant in this connection are defined as follows:
–
AK3 – the functional check of the unit is carried out when a button is pressed for 2 s. It is not
necessary to remove the unit for the functional check.
–
AK4 – the functional check of the unit is carried out through constant self-monitoring and
automatic annunciation of faults. A fault does not lead to loss of the safety function. It is not
necessary to remove the unit for the functional check.
–
AK5 – the functional check of the unit is carried out through constant self-monitoring and
automatic annunciation of faults, also externally. Two faults do not lead to loss of the safety
function. It is not necessary to remove the unit for the functional check.
9.2 ATEX
Because of the EEC Treaty and the system, as specified in the so-called Single European Act, of
separation into manufacture guidelines as per article 118 a, the rules of explosion protection are
currently undergoing major changes. The guidelines as per article 100a are directed at the
manufacturers of units. The guidelines of article 118a affect the operators of plants and the
operation of units and protection systems. These are aimed at protecting the employees.
ATEX 100a – also known as the EC Ex-Protection Directive – regulates, for the whole of Europe,
the manufacture of equipment and protective systems intended for use in potentially explosive
atmospheres. Safety devices, controlling devices and regulating devices intended for use outside
potentially explosive atmospheres but required for or contributing to the safe functioning of
equipment and protective systems with respect to the risks of explosion are also covered by the
scope of this Directive.
ATEX 100a was implemented in German law by the new Ordinance on Explosion Protection
(ExVO/12.96).
9.3 ElexV/ 12.96
In addition to the new ExVO, the amended statutory provisions listed in the 2
nd
Ordinance on the
GSG (Equipment Safety Law) also came info force in December 1996, including the new
“Ordinance on Electrical Equipment in Potentially Explosive Atmospheres“ (ElexV/ 12.96).
In contrast to the old ElexV/ 2.80, which regulates the installation and operation of electrical
equipment in potentially explosive spaces, the new ElexV is a pure operative regulation applying
only for the mounting, installation and operation of electrical equipment in potentially explosive
areas. In § 3 section 1 of the new ElexV, however, the plant operator is obliged to take into
operation only such equipment and protective systems that comply with the new ExVO/ 12.96. In
this way, the new ElexV is harmonized with the new manufacture requirements.