Atex: special transformers

Installation in hazardous areas with combustible gases and dusts: reference standard IEC 60079

ATEX is the conventional name used to group two European Union directives, which regulate the equipment used in areas at risk of explosion and the health and safety of workers in such areas. The standard is in fact derived from the words ATmosphères and EXplosives. The reference standard, IEC 60079, defines which installation areas are considered at risk for certain equipment based on the level of danger but also on the presence or otherwise of any combustible gases and dusts. Depending on the probability of the existence of an explosive atmosphere, these areas range from zone 0 (high probability) to zone 1 (medium probability) and zone 2 (unlikely, less than 10 hours per year). Zones 20/21/22 are similarly defined for dusts. A distinction is also made between above-ground and below-ground zones. There are then three categories of products eligible for the various ATEX zones. The category evaluates the behaviour of the product in normal conditions (category 3), frequent fault conditions (category 2) or rare fault conditions (category 1).
In most cases, transformers and reactors are installed in areas with an unlikely explosive atmosphere and in normal operating conditions. Based on the above, EBG is in the process of obtaining certification with the international certifying laboratory TUV for a range of sample products, guaranteeing complete coverage of our entire range for installations in zone 2, category 3. Product certification consists in providing a complete technical description of the products and their accessories, and in conducting a series of tests in the presence of TUV inspectors. The technical file contains: a description of the transformer, the reference standards, the drawings, the list and technical data sheets of the components, the materials used (metallic and non) and the test reports. Moreover, it also includes the instruction manual with references to standards 60079-14-17 and -19 for placement into service, information concerning maintenance and repair, the certificate of conformity, ATEX product certificates and the risk analysis. The tests are not limited to the routine type, rather special tests are also required, such as for example the heat test to be performed at 110% of the load and the measurement of hot spots, but also pressure and functional tests for hermetic enclosures.
In addition to the category, maximum allowed temperatures are defined for the specific zone (from T1 to T6), as well as the level of danger of the combustible gas (from IIA not very dangerous to IIC most dangerous). The category is also defined by the symbol Ga (category 1) and Gc (category 3). EBG is able to guarantee the following TUV branded certification for our oil-filled transformers: Ex pzc ic oc d Gc and gas protection II 3G IIB T4.