This paper analyses the electrocution hazard in three-phase electrical networks that operate with the neutral point isolated from ground. The following cases are analyzed: short low-voltage electrical networks, long low-voltage electrical networks and highvoltage networks. In high voltage electrical networks, touching a phase is always dangerous even if the insulation resistances are considered to be infinitely high. The analyzed cases show that in three-phase electrical networks with ground-isolated neutral point, the value of the current which passes through the human body depends on its electrical resistance as well as on the insulation resistances of the phases to earth.
Static electricity represents one of the potential ignition sources for the explosive atmospheres. The test methods for materials, in general, and especially the test methods for textile fabrics for assessment of the protective performances in static electricity, have known a permanent evolution alongside newly developed electrostatically dissipative materials. Within the National Institute of Research and Development for Safety in Mines and Explosion Protection (INCD-INSEMEX) new testing stands had been developed and new testing methods had been implemented for assessment of the charge dissipative capacity, in accordance with the European standards requirements. By modernizing the laboratory testing/research-development capacity, the physical tools for testing of materials are assured, having in view conformity assessment with the European Directives requirements, in the framework of the Notified Body for Conformity Assessment (OEC-INSEMEX). The paperwork presents aspects regarding competency testing provided in the RENAR policy for accredited or accrediting-in-progress laboratories, as requirement for proving and monitoring laboratory competency for testing/calibration in the field for which accreditation was applied for/granted.
Abstract. The dust cloud is the main form of existence of combustible dust in the production area and together with the existence of effective ignition sources are the main causes of dust explosions in production processes. The minimum ignition temperature has an important role in the process of selecting the explosion-protected electrical equipment when performing the explosion risk assessment of combustible dusts. The heated surfaces are able to ignite the dust clouds that can form in process industry. The oil products usually contain hydrogen sulfide and thus on the pipe walls iron sulfides can form, which can be very dangerous from health and safety point of view. In order to study the influence of the pyrophoric sulfide over the minimum ignition temperature of combustible dusts for this work were performed several experiments on a residue collected from the oil pipes contaminated with commercially iron sulfide.
Non-electrical equipment has been used for over 150 years in industries with potentially explosive atmospheres and great experience has been gained with regard to the application of protective measures to reduce the risk of ignition down to an acceptable safety level. The use of non-electrical equipment in explosive atmospheres required the development of specific requirements with regard to the concept of protection against the ignition of explosive atmospheres, which to clearly define protection measures and to include the experience gained and extended over the years. The practical studies, laboratory research and methods for assessing and testing the hazard of ignition by hot surfaces presented within the paper have as main purpose the improvement of ignition hazard assessment in different operating conditions.
The paper describes the results obtained during the experimentation of a new method that allows an in site verification of the electric systems for ignition of the electric detonators part of the special trucks for prospecting works, aiming to reach an adequate level of safety in operation. By this method, for in field verification of the electric detonators' ignition system that is mounted in the special trucks for prospecting works, based on the acceptance criteria and the operating ways on the safety parameters, the following are tested: insulation resistance, output energy and output voltage. Employing the verification method in situ prevents the operators electrocuting hazards, unexpected firing of electric detonators or misfiring in the blasting work itself, after the explosive charge was lowered into the prospecting hole. The method has successful experimented on site for 4 special trucks and it has implemented to INCD-INSEMEX Petrosani for testing programme of electric initiation system integrated in prospecting trucks in order to assessing the conformity of products in the voluntary field.
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