{"id":2252,"date":"2022-09-19T13:53:42","date_gmt":"2022-09-19T16:53:42","guid":{"rendered":"https:\/\/blinda.com.br\/novo\/equipamentos-com-tipo-de-protecao-por-seguranca-aumentada-ex-eb-ex-ec\/"},"modified":"2022-10-19T13:27:47","modified_gmt":"2022-10-19T16:27:47","slug":"equipment-with-increased-safety-protection-type-ex-eb-ex-ec","status":"publish","type":"post","link":"https:\/\/blinda.com.br\/en\/equipment-with-increased-safety-protection-type-ex-eb-ex-ec\/","title":{"rendered":"Equipment with increased safety protection type – Ex \u201ceb\u201d \/ Ex \u201cec\u201d"},"content":{"rendered":"

Equipment with protection type Ex \u201ce\u201d (increased safety) is manufactured with additional<\/strong> protective measures to reduce, with a high degree of certainty, the possibility of excessive temperatures of arcs and sparks occurring inside or outside this electrical equipment, which do not occur in normal operation.<\/p>\n

It must be pointed out that an explosive atmosphere containing flammable gases present at the installation site can eventually enter the interior of the Ex \u201ce\u201denclosure, thus providing a high degree of safety against the possibility of hot spots with temperatures above the limit temperature and the occurrence of ignition sources inside the equipment and in parts exposed to explosive atmospheres.<\/p>\n

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Representation of the increased safety protection type – Ex \u201ce\u201d<\/figcaption><\/figure>\n

In the event of any anticipated overload situations, Ex \u201ce\u201d equipment must meet specific requirements on topics such as connectors, wiring, components, insulation distances in air and measured distances on insulating materials (creepage distances), mechanical impacts, vibration resistance, and the degree of protection against ingress of water and dust into the enclosure.<\/p>\n

This increased safety protection technique is applicable to electrical equipment that does not generate sparks or high temperatures under normal operating conditions and under some abnormal conditions specified in the respective Standard.<\/p>\n

As typical <\/em>examples of equipment where the Ex e increased safety protection type is normally applied, possibly including combination with other protection types, can be cited: Three-phase induction motors with squirrel-cage rotor, power transformers, current transformers (electromagnetic and Rogowski<\/em><\/strong> coil) and voltage transformers, measuring instruments, luminaires, terminal boxes, junction boxes and connection boxes for electrical equipment and enclosures for instrumentation, automation, electrical and telecommunications \u201cEx\u201d equipment and panels.<\/p>\n

From a historical point of view, the type of protection of equipment for installation in explosive atmospheres by increased safety was developed during the 1940s in Germany, being initially standardized in German Standard VDE 0170 – Part 6, later in European Standard CENELEC EN 50019 in 1977 and at the present time defined in adopted Brazilian Standard ABNT NBR IEC 60079-7.<\/p>\n

In 1906, the director of the Bergbau Versuchsstrecke<\/em> – Mining Test Facility (BVS) research laboratory for coal mines in Germany had already published the result of an investigative study that fundamentally described the principles of explosion-proof enclosure protection and other equipment protection techniques for installation in explosive atmospheres, such as oil immersion and increased safety.<\/p>\n

In the late 1940s, after the Second World War, the Physikalisch Technische Bundesanstalt<\/em><\/strong> (PTB), at that time still called the Physikalisch-Technische Reichsanstalt<\/em> (PTR), carried out comprehensive research for the implementation of further developments to this \u201cEx\u201d device protection concept, which had already been included in the first edition of the German standard VDE 0170-6 on the increased safety \u201cEx\u201d type of protection (Erh\u00f6hte Sicherheit<\/em><\/strong>).<\/p>\n

This research has determined the measures necessary to avoid the risk of sparking or excessive surface temperatures from electrical equipment intended for installation in classified areas containing flammable gases, through the use of special terminal devices for fixing cables, greater insulation and creepage distances, high quality insulating materials, as well as temperature limiting and monitoring systems.<\/p>\n

The greatest emphasis in those PTB surveys on increased safety was on \u201cEx\u201d<\/strong> electric motors<\/strong>. Participating in these studies and research, along with the PTB, were some traditional electric motor manufacturers, such as Siemens, AEG, and Loher.<\/p>\n

From a construction point of view, many Ex \u201ce\u201d devices can be \u201cvisually<\/em>\u201d distinguished from other industrial equipment for application in non-classified areas only by their marking. For this reason, a major challenge, when this type of Ex \u201ce\u201d protection was launched in the 1950s<\/strong>, was to convince the authorities and users in the various countries of Europe and other continents of its safe application even in Zone 1 classified areas, based on the standardization in which the German \u201cEx\u201d equipment manufacturers and the PTB<\/strong> had been actively involved over the previous decades.<\/p>\n

The results of the research carried out by the PTB remained for a few decades as an Ex-protection technique particularly used in Germany and later in other European countries. The initial letter \u201ce\u201d from the German term \u201cincreased safety<\/em><\/strong>\u201d (erh\u00f6hte sicherheit<\/em><\/strong>) became the international symbol for the \u201cEx\u201d protection type \u201ce\u201d, which was recognized with the publication of the first edition of IEC Standard 79-7<\/strong>, prepared by IEC TC-31 in 1969<\/strong>.<\/p>\n

Equipment in which arcs or sparks or high temperatures can occur during normal operation (such as circuit breakers, contactors, relays, and power switches) cannot be manufactured with this Ex \u201ce\u201d protection type alone,<\/p>\n

The Ex \u201ce\u201d protection type is not applicable to electrical equipment or components that generate sparks under normal operating conditions, such as circuit-breakers, contactors, switches, relays, and pushbuttons since this protection technique is based on the concept of preventing<\/strong> the generation of sparks. For the protection of sparking components, other types of \u201cEx\u201d protection are applicable, such as individually certified components containing plastic housings of the \u201cflame-proof<\/em><\/strong>\u201d type and external terminals in increased safety, with combined Ex \u201cdb eb IIC Gb\u201d<\/strong> protection.<\/p>\n

The \u201cEx\u201d protection technique for increased safety provides the devices with an Equipment Protection Level (EPL Gb or EPL Gc<\/strong>), which makes them safe for installation in Zone 1 or Zone 2 hazardous areas respectively. Thus, with the Gb<\/strong> protection level, the Ex \u201ceb\u201d equipment can be installed even in places where the presence of explosive atmospheres can occur under normal<\/strong> operating conditions of the process equipment.<\/p>\n

The adopted Brazilian Technical Standard ABNT NBR IEC 60079-7<\/strong> (Explosive Atmospheres – Part 7: Equipment protection by increased safety \u201ce\u201d<\/em>) <\/strong>establishes the normative requirements for the design, evaluation, manufacturing, and testing of these types of \u201cEx\u201d equipment. This Brazilian Technical Standard was developed and has been periodically updated by the Brazilian Mirror Subcommittee SCB 003:031 (Explosive Atmospheres<\/em>) of ABNT\/CB-003 (Electricity<\/em>), being initially published by ABNT in 2008 (canceling and replacing the existing ABNT Standard NBR\u00a09883\/1995) and subsequently updated in 2018, establishing the normative requirements for the design, evaluation, manufacturing and testing of these types of \u201cEx\u201d equipment.<\/p>\n

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Cover Sheet of the adopted Brazilian Technical Standard ABNT NBR IEC 60079-7 \u2013 Ex \u201ce\u201d<\/em><\/figcaption><\/figure>\n

According to this type of Ex \u201ce\u201d protection, the required manufacturing requirements must provide a high level of safety against the generation of ignition sources during normal operation. In the event of any foreseeable overload situations, the manufacture must meet specific requirements on various topics, such as connectors, wiring, components, insulation distances in air and measured distances over insulating materials (creepage distances), mechanical impacts, vibration resistance, the degree of protection against ingress of water and dust inside the enclosures. Particularly for the Ex \u201ceb\u201d<\/strong> protection type, attention must be paid to those parts of electrical equipment that could show large temperature changes, such as the windings of an Ex \u201ce\u201d <\/strong>electric motor in the event of its rotor jamming.<\/p>\n

Manufacturing design measures make sure that Ex \u201ce\u201d <\/strong>equipment does not become a source of ignition, even in the event of an operating fault. This requirement is mainly achieved by the following safety measures:<\/p>\n