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Relays and Contactors
Published in Joseph E. Fleckenstein, Three-Phase Electrical Power, 2017
Relays located within hazardous areas preset some unique requirements. Hazardous areas are defined as those areas that may contain flammable gases, liquids, fibers, or dusts. If a conventional EMR is located in a hazardous area and the contacts of that relay either close or open, an arc will be generated. That arc, if it is of an adequately high-energy level, can ignite gases and cause an explosion. In short, conventional EMRs are not suited for use in a hazardous area. Special precautions are needed when using arc-generating devices in a hazardous area. One viable approach is to use an enclosure that is suitable for hazardous areas. Both explosion proof enclosures and purged enclosures are suitable for hazardous areas. Some of the other possible alternatives for a hazardous area are
Hazardous Area Classification
Published in Siddhartha Mukherjee, Process Engineering and Plant Design, 2021
Broadly, there are two systems which are widely used to classify hazardous areas: class/division system and zone system. The class/division system is used predominantly in the United States and Canada. The rest of the world normally uses the zone system.
Air Leakage Law and Prevention Technology of Coal Spontaneous Combustion in the Goaf of “Isolated Island” Fully Mechanized Caving Face
Published in Combustion Science and Technology, 2023
Li Ma, Su Du, Cheng-Mao He, Rui-Zhi Guo, Wei-Guo Tao
Through two SF6 tracer gas leakage measurements, the air leakage channels between goafs 3301 and 3302, the roadway in the south wing and the track roadway were analyzed, and the air leakage flow field in the goaf was analyzed by numerical simulation, and the hazardous areas of coal spontaneous combustion, so as to carry out targeted prevention and control measures. The research route is shown in Figure 3.