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According to the provisions of the 5th edition of the standard IEC 60079 – 7, equipment protection by increased safety “e”, for Level of protection “eb” and “ec” electrical machines, if the rated voltage exceeds 1 kV, type tests in explosive mixtures have to be carried out, in order to certify such an electrical machine. The purpose of this paper is to provide some considerations regarding the impulse ignition test for level of protection “eb” and ignition test for levels of protection “eb” and “ec” stator insulation systems of explosion proof electric motors and also to present a case study regarding such tests conducted in the specialized laboratory of INSEMEX Petrosani, on a stator insulation winding system of a 6 kV electric motor type of protection Ex eb IIC Gb, case study which will assist manufacturers in designing appropriate stator winding insulation systems for increased safety type of protection electric motors.

The type of protection flameproof enclosure “d” consists in placing the parts that could ignite an explosive atmosphere inside of an enclosure that can withstand the pressure developed during an internal explosion of an explosive mixture and which prevents the explosion transmission to the explosive atmosphere surrounding the enclosure. The protection to explosion must remain valid even in case of an internal explosion. The maximum surface temperature of electrical equipment is defined as the highest temperature which is attained in service under the most adverse conditions (but within the specified tolerances) by any part or surface of equipment. When determining the maximum surface temperature of a flameproof equipment the temperature of external surfaces is considered. The increase of temperature due to an internal explosion is not considered. The purpose of this paper is to highlight this temperature increase during an internal explosion in case of a flameproof enclosure.

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.

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. Engineers settled the concept that, for IIC areas, have to be necessarily used equipment with cylindrical flame paths, which usually feature a round-shape body that make more complicated the construction of panel boards. EN 60079-1 standard, states that flanged flame paths are allowed in the presence of hydrogen, therefore, in recent years, started the production of “Ex d” explosion-proof enclosures which are usable, as well as with gases of Group IIB, even in the presence of hydrogen. This means that the equipment can be used in an environment containing explosive atmosphere with hydrogen. Acetylene is, therefore excluded, but it has to be considered that the environments with the presence of hydrogen are much more frequent than those with acetylene. The purpose of this paper is to assist manufacturers design flameproof equipment that satisfies the requirements of the standard for group IIB and hydrogen applications in order to smooth the path for certification.

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.

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 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.

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.

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. Electrical equipment that operates in potentially explosive atmosphere, have characteristics specially designed for operation in this area. For security reasons, it is essential that the integrity of these special features be preserved in these areas throughout the life of the installation. Using electric equipment in potentially explosive atmospheres brings forward several particularities therefore the problems that appear during the design, construction and operation of electrical devices and installations brings forward numerous difficulties, their approach requiring special attention considering all the technical, economical and labor safety aspects. The purpose of the paper is to reveal the importance of using appropriate electrical equipment design to be used in potentially explosive atmospheres generated by hydrogen. [ABSTRACT FROM AUTHOR]

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.

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.

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. The purpose of this paper is to present aspects regarding the importance of thermal endurance tests performed on the electrical equipment used in potentially explosive atmosphere. The paper also presents laboratory facilities for performing the thermal endurance test. [ABSTRACT FROM AUTHOR]

The equipment designed for use in explosive atmospheres has to fulfil the requirements of ATEX Directive 2014/34/EU (transposed into Romanian legislation by GD 245/2016). In order to verify the explosion protection characteristics of equipment these shall be subjected to type tests. In case of fluorescent luminaires with type of protection increased safety "e", supplied by electronic ballasts, these shall be subjected to the asymmetric pulse and asymmetric power tests. The purpose of this paper is to present the importance of the asymmetric pulse and asymmetric power tests, and also, to underline the testing methodology developed based on the requirements imposed by the applicable standards. [ABSTRACT FROM AUTHOR]

The evaluation of explosion-proof electrical equipment for certification is particularly important given the risk of explosion and must be minimized. This in order to ensure the safety of life, health of workers, to prevent damage to goods and the environment when they meet the essential security requirements at European level. Directive 2014/34 / EU states that equipment used in explosive atmospheres must be designed to operate without endangering the environment for which it is intended. This paper proposes the study and evaluation of the requirements for the breathing and drainage devices. In order to verify explosion protection, the representative samples made available by explosion-protected equipment manufacturers are tested under the worst possible conditions that may occur in practice. [ABSTRACT FROM AUTHOR]

Where electrical apparatus is to be installed in areas where flammable gases, vapors or mists may be present in the atmosphere, protective measures are applied in order to reduce the likelihood of explosion due to ignition by arcs, sparks or hot surfaces, produced either in normal operation or under specified fault conditions. Protective measures aim to reduce, to an acceptable level, the likelihood that the electrical installation could become a source of ignition. [ABSTRACT FROM AUTHOR]

Inspection is an action that comprises the examination of electrical equipment to be performed without dismantling or with partial removal, where applicable, supplemented by means such as measurements to reach a certain conclusion regarding the state of the equipment in question. Maintenance is a combination of all actions taken in order to maintain or restore an object given that it is able to meet the relevant specifications and requirements to perform its set functions. The paper presents the most important aspects to be taken into account when carrying out inspection and maintenance of electrical equipment used in explosive atmosphere with type of protection flameproof enclosure "d" and increased safety "e" to ensure functionality and the type of protection equipment for safe operation. [ABSTRACT FROM AUTHOR]

The paper brings forward the mechanical malfunctions, due to corrosion, occurred on AG-63 command boxes which are used in the flammable mines of Jiu Valley. Following the assessment of the command boxes, a series of mechanical malfunctions have been highlighted, such as: local and remote button command malfunction; malfunction of the screws of the terminal boxes and those of the inserters; malfunction of the door command levers and of their locking bolts. In conclusion in order to increase the reliability and maintenance level of the command box, and consequently the operational safety of the construction of the box, it is therefore required to reconsider the maintenance policy regarding the mechanical part of the box. [ABSTRACT FROM AUTHOR]

The purpose of the paper is to perform a thorough analysis of the types of breakdowns, both electrical and mechanical, which are likely to occur in the case of electrical drives made up of explosion proof electric motors used in hazardous locations. Based on this analysis, several solutions are identified, in order to enhance the reliability in exploitation and the maintenance of electrical drives consisting of Ex proof electric motors commonly used in the oil and gas industry. These solutions can be used both by explosion proof motor manufacturers and the end users of this equipment in oil and gas applications, in order to enhance the safety against explosion hazard. [ABSTRACT FROM AUTHOR]