Testing explosion protected electrical equipment

Within the framework of type verifications for and testing of electrical apparatus in general, technical tests shall furnish proof of mechanical, thermal or electrical properties as specified in the relevant standards. Some examples for type tests are given in the following  

The majority of the type tests listed above refers to electrical apparatus in general, i.e. these tests are valid for non-explosion protected electrical equipment as well. 

In the following, type tests which are applied exclusively to firedamp-proof or explosion protected apparatus or which represent an enormous potential in material quality verification will be considered in more detail  

1 Tests of the ability of an enclosure to withstand an internal overpressure and for non-transmission of an internal ignition, applied to flameproof - d -enclosures 

2 Partial discharge (PD) measurements applied to components or apparatus subject to electrical stresses, e.g. components according to encapsulation - m or complying with increased safety - e -  

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TGL Technische Gute- und Lieferbedingungen, Technical Regulations for Quality and Delivery) have defined the classification of hazardous areas (TGL 30042) and the requirements for construction and testing of explosion protected electrical equipment (mainly TGL 19491). 

The state of the art - the second edition (and following editions) of the European Standards (EN) (see Table 3.5) - is considered to form an appropriate basis for construction and testing of explosion protected electrical equipment. Other aspects of safety may require revision of established standards. 

For explosion protected electrical equipment manufactured, type tested, certified and commissioned under the ATEX 100a Directive, the marking described in Table 5.2 shall be added by the marking code given in Table 5.3. The Ex in a hexagon has been taken from the old article 100 directives, whereas the B, C, D or E marks for the generation of Harmonized Norms have been deleted. 

The Regulations provide a range of means for assessing conformity. However, as far as electrical equipment is concerned, conformity assessment through a notified body will be the norm, following much the same EC type examination processes and procedures that have been used in the past. There are, however, additional requirements for product quality control and third party audits. In the UK, the Electrical Equipment Certification Service (EECS) and SIRA Test and Certification Ltd already provide conformity assessment services, basing their assessments on the harmonised standards that already exist for explosion-protected electrical equipment the main standards are identified in Chapter 15. 

In the UK, the type testing and certification work has been carried out by the Electrical Equipment Certification Services (EECS), which is part of HSE, and by SIRA Test and Certification Ltd. The Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996 will change this, because they introduce a legal requirement for compliance with the Essential Health and Safety Requirements (EHSRs) and the application of the CE mark using the applicable conformity assessment procedures, which may involve the participation of a notified body. This is a complicated area but, in summary ... 

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