[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-113-1-fire-science-031":3},{"subject":4,"subjectSlug":5,"subjectKicker":6,"subjectShort":7,"question":8,"related":27,"sameNumber":52,"hasEssay":26},"火災學概要","fire-science","火災學 · Fire Science","火災學",{"id":9,"webId":10,"year":11,"session":12,"subject":4,"number":13,"stem":14,"options":15,"answer":20,"answerNote":21,"images":22,"imagesPending":23,"lawTimestamp":11,"explanation":24,"explanationDeep":25,"freq":12,"indexable":26},"fire-113-1-火災學概要-031","fire-113-1-fire-science-031",113,1,31,"在電氣火災研究中，木材、電木等絕緣物中，受電氣火花而碳化，碳化部分會逐漸形成微量的結晶，而變成具有導電性，此現象稱為？",{"A":16,"B":17,"C":18,"D":19},"積污導電現象","沿面放電","金原現象","線圈層間短路","C",null,[],false,"本題考點：電氣火災中絕緣物受火花碳化而轉為導體的機制辨識，即金原現象。\n【正解理由】木材、電木等有機絕緣材料長期承受電氣火花或微小電弧作用時，會逐步熱裂解而碳化，碳化部分進一步生成微量的石墨狀結晶，使原本的絕緣體出現導電性通路，電流沿此通路持續流通並發熱，終致引燃周圍可燃物。此種由絕緣轉為導電的變質過程即稱金原現象，故選 C。\n【逐項排除】\n(A) 積污導電現象係絕緣物表面附著塵埃、纖維並吸收濕氣而形成導電性污損層，因而產生微小放電並逐漸碳化，起因在外部污染與濕氣，而非材料本體受火花碳化結晶。\n(B) 沿面放電指電荷沿絕緣物表面閃絡放電的電氣現象，描述的是放電形態，並未指涉絕緣物本體變質為導體的過程。\n(C) 金原現象敘述相符，為應選項；關鍵字即碳化部分形成微量結晶而具導電性。\n(D) 線圈層間短路係電動機或變壓器繞組的匝間絕緣劣化破壞而導通，屬繞組內部絕緣破壞，與碳化結晶無關。\n【記憶點】火花打久了，絕緣物碳化長出結晶而變成導體，就是金原現象。","電氣火災的成因在本科屬高頻考點，常見類型可依機制分成幾群：接觸不良與過負載造成的過熱、短路電弧、絕緣劣化導電，以及靜電放電。金原現象屬於絕緣劣化導電這一群，其特殊之處在於絕緣體本身變成了導體，而不是絕緣被外來的異物橋接。\n\n整個過程可拆成三個階段。第一階段，插座、開關或配線接頭處因鬆動、積污而反覆產生微小火花，局部溫度極高但作用範圍很小。第二階段，火花的高溫使木材、電木等含碳有機材料發生熱裂解，揮發分逸出而殘留碳質，形成肉眼可見的黑色碳化痕。第三階段，碳化層在持續電弧作用下逐漸有序化，出現微量石墨狀結晶，電阻大幅下降，於是電流開始持續通過絕緣物本體，發熱又回頭加速碳化，形成正回饋，直到溫度足以引燃周圍可燃物。此過程可能歷時數月甚至數年，因此火災調查常在配線器具附近找到明顯的碳化導電痕跡作為研判依據。\n\n易混淆概念對照：積污導電現象的關鍵字是「塵埃與濕氣」，發生在絕緣物的表面，常見於潮濕環境的插座；金原現象的關鍵字是「碳化與結晶」，變質的是材料本體。部分教材以半導體化或石墨化描述同一過程，指的是相同機制的不同稱呼。至於短路痕與熔痕的判別，屬火災調查中另一組概念，用以區分電氣痕跡究竟是起火原因還是受火害後的結果。與之對照，接觸不良的機制是接觸電阻升高而在接點局部發熱，過負載則是電流超過導體容許值而使整段配線普遍發熱，兩者在痕跡分布上與金原現象沿碳化通路集中的形態明顯不同。\n\n相關考點延伸：命題常把四種電氣現象並列，要求選出與定義相符者，記憶時抓住每個名詞的一個獨有關鍵字最有效率。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-113-1-fire-science-030","有關煙控分析中「等效流動面積」的定義，下列敘述何者正確？",30,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-113-1-fire-science-032","可燃物在大氣中僅因受熱致使溫度升高而引發燃燒的最低溫度稱為：",32,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-113-1-fire-science-029","火場中的單位長度光學密度為 1 m-1 時，此火場中的發光物體之能見度約為多少公尺？",29,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-113-1-fire-science-033","對於金屬鈉的敘述，下列何者錯誤？",33,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-113-1-fire-science-028","關於火場中生成的 CO 對人體的危害，下列敘述何者正確？",28,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-113-1-fire-science-034","有關熱傳導的敘述，下列何者正確？",34,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-112-1-fire-science-031",112,"在長寬高為10×10×4 公尺的密閉空間中以高壓式二氧化碳作為滅火防護設備。若欲將空間中的氧氣濃度降至 15%以下以達到鈍化效果，至少應加入多少立方公尺的二氧化碳？",{"webId":58,"year":59,"stem":60,"number":13},"fire-111-1-fire-science-031",111,"常見消防機關宣導，使用延長線勿將其綑綁，以免引發火災，究其原因為何？",{"webId":62,"year":63,"stem":64,"number":13},"fire-110-1-fire-science-031",110,"有關影響粉塵爆炸的因素，下列何者錯誤？",{"webId":66,"year":67,"stem":68,"number":13},"fire-109-1-fire-science-031",109,"建築物火災在閃燃發生後之全盛期火災的特性，不包括下列何者？",{"webId":70,"year":71,"stem":72,"number":13},"fire-108-1-fire-science-031",108,"假設建築物外部風速為 V 時，其迎風面的風壓為 P，當風速提高為 2V 時，建築物所受風壓變為：",1785129966358]