Constructional Properties and Evaluation Methods of the Non-Incendive Type of Explosion-Proof Electrical Apparatus

비점화(非點火)(Non-Incendive)형(型) 방폭(防爆) 전기기기(電氣機器)의 구조특성(構造特性) 및 평가방법(評價方法)

In the hazardous areas where explosive substances in the form of gases, vapor or mists exist, electrical apparatus and installations must be of explosion-proof construction to prevent or limit the danger of the ignition of potentially explosive atmosphere. In Korea, six types of protection have been specified in the government regulations at present: flameproof enclosure, pressurization, oil immersion, increased safety, intrinsic safety, and special types. If electrical apparatus are made of explosion-proof construction in a way other than five above-mentioned types, and their performance is tested and approved by the reponsible authorities, they may be categorized as special type apparatus. In this paper, we introduced a special type of explosion-proof electrical apparatus, called non-incendive type, and presented its constructional requirements. We also investigated evaluation methods of non-incendive type apparatus to assure the explosion-proof performance, and proposed a new classification method of hazardous areas using probabilistic concept.