Diagnosis of Abnormal Heat Generation in the Connection Part in Low Voltage MCCBs for Fire Risk Prediction

Abstract

This study is conducted to determine the critical temperature under normal current flow by estimating normal heat generation; the saturation temperature of the connecting part of a circuit breaker is simultaneously measured by sub-dividing the rated current of molded case circuit breaker (MCCB) into 10 steps. Further, a risk analysis was conducted via an investigation of thermal characteristics. To this end, five types of MCCBs were selected while building a temperature test box; further, the heat generation temperature of the three phases on the line and load sides was measured using the sub-divided load current to represent the electrical heat variation and a high-current-generating tester real-time. The results the test, demonstrate that the temperature of the connecting part of the MCCB stably increased; in addition, the standard of the heat generation could be established and the load amount could be predicted by measuring the temperature variation. Meanwhile, the heat generation temperature was different for different types of wirings such as power lines and Busbar. Further among the R, S, and T phases of the MCCB, S phase temperature was slightly higher than those of the others. This study can serve as a theoretical reference for future applied research on the dangers of fire due to the heat generation of the connecting part of the MCCB, wherein the risks of abnormal heat generation need to be analyzed. The results obtained can be applied not only to prevent the carbonization accidents of MCCBs installed inside distribution panels being used at industrial sites, but also to manage the risks of the distribution circuit breaker and prevent the electrical fire.