Earticle

The purpose of this study is to compare the characteristics of transformers according to their types and to analyze, and investigate the cause of, the failure patterns of 3 phase mold transformers collected from places where accidents have occurred. Since a mold transformer is small in size compared to a general transformer, it can easily be installed in a receiving substation. However, in the case of a mold transformer, it is difficult to diagnose its heat radiation and abnormal phenomenon during system operation. From the 3 phase mold transformer to which failure has occurred, a trace of carbonization was found between the U-phase and V-phase, and a trace of crack was found at some part of the secondary side of the U-phase. The metal structure of the copper cable used as electric cable is amorphous and has no direction and crystallinity. However, it was found from the metal structure of the bus bar (copper) of the damaged 3 phase mold transformers that crystalline arrays unique to copper cables disappeared and a new shape of crystal structure was formed. It can be seen that the copper particles had comparatively homogeneous voids and that their size was enlarged. In addition, it was found that the voids and crystal particles were bigger at the surface of the conductor than at the center.

This treatise deduced the reason of fire set in the Korean restaurant at 1098-1 Eobang-dong, Gimhae-city, Gyeongsangnam-do, which occurred at 04:24 on July 25th 2008. Data about this fire accident was collected from both the people who were around the firing place, a restaurant manager and the first comers to the Samjung center. After inquiring for a possibility of incendiary in order to collect possibilities of the insurance, incognizant causes of fire, a gas leak, electrical factors we reached to a conclusion that this fire accident was from tracking phenomenon of a circuit board of the air conditioner.