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영어

In a recent refrigerator fire, there is a case where it was concluded that the fire was caused by other reasons, such as overcurrent, as a result of analyzing evidence that could be attributed to a relay abnormality. control unit during fire investigation, various devices are connected to the load side and the arc generated when the relay is operated repeatedly is eliminated. It was designed and tested as an experiment to check the possibility of fire that can occur by deforming the contact point. As a result of the experiment, it was observed that severe melting and damage were seen at the contact point, and that it was difficult to distinguish the boundary between Ag and Cu. As a result of X-ray confirmation, distortion and flattening of the contact point were observed. As a result of EDS analysis, most of the sample contacts contained Ag, but in the case of the relay contacts connected to the load, Ag decreased and O, Cu, and Sn increased. As a result, the higher the frequency of use of the relay, the higher the temperature and resistance due to the arc inside, and the change of the shape, surface, and composition of the contact could lead to ignition. It is suggested that appropriate countermeasures against relay fires such as method guidance are necessary.