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The paper aims to address what types of protection can be applied to galvanic elements and batteries that are used in potentially explosive atmospheres. In order to keep electrical equipment in operation in environments with potentially explosive atmospheres under harsh conditions, including galvanic elements and batteries, a certain type of protection must be applied for safe operation. The types of protection applied to galvanic elements and batteries are made in accordance with EN 60079-0 and in compliance with the requirements of the ATEX directive - 2014-34 EU. Galvanic cells and batteries in order to be used in potentially explosive environments must meet certain conditions, namely: All galvanic cells in a battery must have the same electrochemical system, design and rated capacity, and must be made by the same manufacturer, All batteries must be installed and used so as to be within the permissible limits defined by the galvanic cell or battery manufacturer, Primary and secondary galvanic cells or batteries must not be used within the same equipment enclosure if they are easily interchangeable, The technical standard EN 60079-0 applies to all electrical equipment and covers factors directly related to the types of protection applied to electrical equipment operating in hazardous areas where the hazard may be caused by gases, vapours, mist, dust, fibres or flammable substances.

When using electrical equipment in installations operating in hazardous areas endangered by potentially explosive atmospheres, care shall be taken also to the selection of such equipment. The correct selection of equipment for use in potentially explosive atmospheres must be considered in the design phase of an installation and verified in the mounting phase. Equipment intended for use in potentially explosive atmospheres must be designed, manufactured and placed on the EU market considering the provisions of the ATEX Directive 2014/34/EU. In order to adequately select the electrical equipment, the provisions of the regulations in force must be considered together with the provisions of applicable standards.

The research carried out in the specialized Laboratory of the National Institute for Research and Development in Mine Safety and Explosion Protection -INSEMEX Petrosani has identified the causes of high pressure peaks occurrence in the case of large electric motor enclosures as: the extremely large internal volume, the geometrical shape of motor enclosures and the very intricate and complex internal arrangement of such motor enclosures, having in mind the tendency of motor manufacturers for chemical and petrochemical industry to manufacture motors having more complex geometrical shapes. These results proved to be very useful in assisting designers of large flameproof electric motors to improve motors design so as to make them more reliable when testing in explosive mixtures.

The purpose of this paper is to present the tests carried out on cable entries with a flameproof enclosure protection type used in potentially explosive atmospheres. Assessment of explosion-protected electrical equipment is accomplished through tests carried out in accordance with the standard SR EN 60079-0, which includes all general requirements for explosion-protected electrical equipment. The requirements of this standard are supplemented with those for each type of protection in separate standards. To elaborate this paper, the requirements in force were studied. It resulted that a stand for sealing test of cable glands with flameproof enclosure protection type is required. This test is essential in the process of certification of the equipment used in explosive areas. In the first stage of the project, the test stand was conceived, whose design has been considered taking into account the specifications of the reference standard for electrical equipment used in potentially explosive atmospheres. The paper also presents the stand for sealing test of cable glands (with type of protection flameproof enclosure). This stand was developed this year at National Institute for Research and Development in Mine Safety and Protection to Explosion-INSEMEX Petrosani.

The special characteristics providing protection to explosion for equipment design for use in potentially explosive atmospheres must be preserved during their entire period of use. Thus, the equipment designed for use in potentially explosive atmosphere shall be subjected to specific inspections in order to verify that the characteristics on which explosion protection is based were not depreciated in time. The purpose of the paper is to underline the importance of inspections in case of equipment intended to be used in potentially explosive atmospheres and to provide specific recommendations in this matter.

Evaluation of explosion-proof protected electrical equipment in scope of certification is extremely important considering the risk of explosion that has to be minimized in order to ensure life safety and health of workers and to prevent damaging of property and the environment, as well as free movement of goods when they meet the essential safety requirements at European level. Most of the equipment operating in potentially explosive atmospheres is represented by electric motors, which in most situations act on various other elements (e.g. pumps, valves, fans etc.). Even if electric motors for explosive atmospheres are designed and manufactured following some of the same principles as the ones used for other electric machinery, they have certain particularities related to their field of use. Thus, a series of specific restrictions and tests are required to be considered in their case. The purpose of this paper is to present the importance of the specific tests for electric motors with type of protection increased safety „e” designed to be used in explosive atmosphere.

The characteristics providing protection to explosion of equipment designed for use in potentially explosive atmospheres must be preserved during their entire period of life. Repairing is defined as the action to restore faulty equipment to its fully serviceable condition complying with the relevant standard (the standard to which the equipment or parts of equipment were originally designed). Repairing of explosion-proof equipment must be performed considering the prescription of the applicable harmonized standards and the specific type of protection(s) involved. This paper is focused on some particular aspects related to repairing of explosion-proof equipment.

The flameproof enclosure type of protection is still one of the safest because it is based on a very simple and, therefore, unlikely fallible technology. If an explosive atmosphere penetrates an enclosure producing a trigger, the explosion occurs, but it remains confined within the enclosure. EN 60079-1 standard, states that flanged flame paths are allowed in the presence of gases and vapours of Group IIB, but cannot be used with gases and vapours of Group IIC. Also, flame transmission tests for Group IIB equipment are carried out at atmospheric pressure, whereas for Group IIC equipment they are conducted (depending on the testing method applied) at a higher initial pressure. The purpose of the paper is to perform a thorough study upon the differences between testing of flameproof electric motors of Group IIC, compared to electric motors of Group IIB gases and vapours, in terms of testing conditions required by the standard and how the explosion group influences the maximum explosion pressures and explosion pressure development, when tested in explosive mixtures of gases and vapours. The purpose of this paper is to assist manufacturers in designing flameproof electric motors that satisfy the requirements of the specific standard for either Group IIB or Group IIC applications in order to smooth the path for certification.

Explosion-proof equipment must be designed so that the ignition of the surrounding explosive atmosphere to be avoided. This is very important because an explosion can have particular implications over goods, life and not least over the environment. One of the ignition sources of an explosive atmosphere is represented by hot surfaces. Each equipment designed to operate in explosive atmospheres develops a maximum surface temperature. The specific standards used to assess explosion protection characteristics cover only indirectly and in part the factors influencing the maximum surface temperature. By this study, using a standardized testing methodology, the factors influencing the maximum surface temperature in case of explosion-proof luminaires with type of protection flameproof enclosure d and increased safety e were pointed out and analyzed (i.e. maximum designed ambient temperature of the luminaire; placement of temperature sensors to capture the points where the maximum surface temperature is recorded; type, power and size of the light source installed in the luminaire; operating position of the luminaire; supply voltage of the luminaire). The measures to be taken, in order to determine as accurately as possible the maximum surface temperature, in relation with the influencing factors, were also identified.

The research carried out in the specialized Laboratory of the National Institute for Research and Development in Mine Safety and Explosion Protection INSEMEX Petrosani has identified as causes for the occurrence of high pressure peaks in the case of electric motor enclosures, the internal volume, the geometrical shape of motor enclosures and the very intricate and complex internal arrangement of such motor enclosures (especially in the case of large motor enclosures), having in mind the tendency of motor manufacturers for chemical and petrochemical industry to manufacture motors having more complex geometrical shapes.

Equipment operating in installations endangered by the occurrence of potentially explosive atmospheres have special features designed in order to make them suitable for operations in such areas. Equipment designed for use in potentially explosive atmospheres shall be placed on the EU market considering the provisions of the ATEX Directive 2014/34/EU and the harmonized European standards under this Directive. Even if equipment is placed on the EU market in accordance with ATEX Directive 2014/34/EU provisions, the special characteristics providing protection to explosion can be invalidated in installation design, erection, operation, inspection, maintenance or repairing phases. In order to prevent invalidation of explosion protection characteristics an important accent is placed on training and authorization of personnel involved in design, mounting, operation, inspection, maintenance or repairing of equipment/installations operating in potentially explosive atmospheres.

The electric power drive systems consisting of three phase induction motor and static frequency converter are designed to enhance the performance on site, by diminishing the energy consumption, optimization of the technological processes and the reduction of costs for the maintenance and repairs of the equipment. The paper presents some important issues concerning the selection of inverter fed flameproof electric drives in the field of potentially explosive atmospheres of gases and vapors by ensuring a correct risk management against the hazard of electric sparks as well as excessive temperatures.

Explosive risk occurs in all activities involving flammable substances in the form of gases, vapors, mists or dusts which, in mixture with air, can generate an explosive atmosphere. As explosions can cause human losses and huge material damage, the assessment of the explosion risk and the establishment of appropriate measures to reduce it to acceptable levels according to the standards and standards in force is of particular importance for the safety and health of people and goods.There is no yet a recognized method of assessing the explosion risk, but regardless of the applied method, the likelihood of an explosive atmosphere occurrence has to be determined, together with the occurrence of an efficient ignition source and the magnitude of foreseeable consequences. In assessment processes, consequences analysis has a secondary importance since it’s likely that explosions would always involve considerable damage, starting from important material damages and up to human damages that could lead to death.The purpose of the work is to highlight the important principles and elements to be taken into account for a specific risk assessment. An essential element in assessing the risk of explosion in workplaces where explosive atmospheres may occur is technical installations and personal protective equipment (PPE) that must be designed, manufactured, installed and maintained so that they cannot generate a source of ignition. Explosion prevention and protection requirements are governed by specific norms and standards, and a main part of the explosion risk assessment is related to the assessment of the compliance of the equipment / installation with these requirements.

The paper deals with a comprehensive reliability analysis of the conveyor belts belonging to an underground coal mine in the Jiu Valley, Romania. As resulted from the mine management reports, the transportation system is responsible for many downtimes and is a real bottleneck in the constant and adequate production, and the suspicion is the weak state of belt conveyers, which are the spinal column of the extraction process. For this reason, a comprehensive reliability analysis has been decided, in order to deliver a maintenance-upgrading plan.