火场冷却条件对铝导线过电流熔痕的影响研究

Study on the Influence of Cooling Condition of Fire Field on Overcurrent Melting Trace of Aluminum Wire

过电流是一种引发火灾的常见电气故障,金相法是过电流熔痕的主要鉴别方法。在实际火灾中,过电流铝导线会受到冷却条件的影响,金相组织发生变化。模拟水冷、火场温度下自然冷却和室温下自然冷却等条件,对铝导线过电流熔痕的宏观形貌和金相组织进行观察分析。结果表明,室温下自然冷却过电流铝导线的表面残留物较多,金相组织晶粒大,大、小气孔均存在;水冷过电流铝导线的表面残留物较少,金相组织的晶粒更小且气孔更大、更密集;火场温度下自然冷却过电流铝导线的表面发灰且不同于过电流形成的弯折部位,金相组织晶粒更大且气孔也更大。

Overcurrent is one of common electrical failure.Metallographic method is the main method to identify overcurrent melting trace.Due to the cooling conditions in actual fire,the metallographic structure of the overcurrent aluminum wire will change.In this paper,the macroscopic morphology and metallographic structure of the overcurrent melting trace of aluminum wire is observed and analyzed under the conditions of water cooling,natural cooling at the fire site temperature and natural cooling at room temperature.The experimental results show that there are more residual on the surface of overcurrent aluminum wire under natural cooling condition at room temperature,the grain of metallographic structure is large,and with both big and small pores.There are more less residue on the surface of water-cooled overcurrent aluminum wire,the grain of the metallographic structure is smaller and the pores are larger and more intensive.The surface of the aluminum wire at fire field temperature is gray and the bents formed by overcurrent are different,the grain structure of the metallographic structure is bigger and the pores are larger.