Research on Temperature Change of Local Steel Members in Main Transformer Room of Substation Based on Fire Condition

Based on the special situation of the main transformer room of the substation in the event of a fire, the influence of the standard, electrical and hydrocarbon fires that may occur in the main transformer room of the substation on the steel members without fire protection is studied, the temperature changes of the back fire surface of steel members with different section factors and different load ratios under three fire heating modes were studied by means of experiment and numerical simulation. The experimental results show that the time range for all steel members to reach the critical temperature is 2–22 min. Compared with the standard fire, the section factor of the steel member has a greater influence on the temperature rise in electrical and hydrocarbon fires. In addition, the time to reach the critical temperature of steel members under electrical and hydrocarbon fires is significantly lower than that of steel members under standard fires, with a decrease of more than 70 %, up to 85.7 %. The analysis of multiple sets of different working conditions shows that the larger the load ratio of steel members under the three fire heating modes, the shorter the time for the back fire surface to reach the critical temperature, and the two have a strong correlation. Finally, the index based on the time when the temperature of the back fire surface of the steel member reaches the critical temperature has certain reference value for the fire protection design of the main transformer room of the substation under various fire heating modes.