• 대한안전경영과학회지
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• 제24권4호
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• pp.101-107
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• 2022

To test a flameproof enclosure for the safety certificate, a reference pressure of explosion needs to be determined. However, the explosion pressure may be changed according to relative humidity of explosive gases. Therefore, the guideline on relative humidity should be recommended for measuring the explosion pressure for accurate and reproducible testings. This study examined the relationship of explosion pressure with relative humidity of hydrogen (31 vol %)-air and acetylene (14 vol %)-air mixture gases. The explosion pressures were measured by increasing the relative humidity of the gases by 10 % from dry state to 80 % in a cylindrical explosion enclosure of 2.3 L. on ambient temperature and atmospheric pressure (1 atm). The maximum explosive pressures were remained almost constant until the relative humidity reached 10 % for the hydrogen-air mixture and 20 % for the acetylene-air mixture. However, the maximum explosive pressures linearly decreased as the relative humidity increased. Based on the results of the study, it would be recommended to use 10 % relative humidity for the hydrogen-air mixture and 20 % for the acetylene-air mixture as the critical value in testing a flameproof enclosure.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.313-314
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• 2006

• 대한안전경영과학회지
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• 제25권1호
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• pp.51-58
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• 2023

Determination of explosion reference pressure is important in designing and testing flameproof enclosures (Ex d). Although relative humidity affects to explosion pressure, its effect is not well investigated for the gas group IIB, IIA, and I. This study tested explosion pressure for Ethylene (8 vol.%), Propane (4.6 vol.%), and Methane (9.8 vol.%), which are the representative gas of the gas group IIB, IIA, and I, at ambient temperature and atmospheric pressure (1 atm) under different relative humidity (0% ~ 80%). Ethylene- and Propane-air mixed gases generally tended to decrease as the relative humidity increased; however, explosion pressure was largely dropped at 20% of relative humidity compared to 0% and 10% of relative humidity. On the other hand, Methane-air mixture gas showed similar pressures at 0% and 10% of relative humidity; but no explosion occurred at more than 20%. The results of this study can be used in setting a testing protocol of explosion reference pressure for designing and testing a flameproof enclosure.

• 한국가스학회지
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• 제20권3호
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• pp.30-37
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• 2016

내압 방폭전기기계 기구는 인화성 가스가 존재하는 위험장소에서 사용되어도 인화성 가스의 점화원이 되지 않는 구조로 이루어져야 한다. 또한 전기 스파크를 발생시키는 부품이 점화원이 되어 기계 기구 내부에서 폭발 시 최대 압력에 견디고 내부 화염이 외부로 전파되어 가스나 증기 폭발을 일으키지 않도록 설계되어야 한다. 본 연구에서는 화염 틈새를 통해 외부로 분사되는 연소 생성물의 분사가 외부 가스나 증기를 점화시킬 정도의 온도나 에너지를 가질 수 없도록 하는 MESG(Maximum Experimental Safe Gap)의 중요한 물리적인 메커니즘에 대해 규명하였다. IEC 60079-20-1:2010 기준에 의해 프로판- 아세틸렌-공기로 이루어진 3성분계 혼합가스의 MESG를 실험하여 MESG 값을 측정하고 가스 폭발시의 최대 폭발압력을 측정하였다. 결과로는 아세틸렌 가스 보다는 폭발력이 낮은 프로판 가스의 조성이 MESG 값과 폭발압력에 더욱 큰 변수로 작용함을 알 수 있었다.

• 한국가스학회지
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• 제20권1호
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• pp.29-39
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• 2016

폭발성 가스가 존재하는 위험장소에서 사용하는 전기기기는 폭발성 가스의 점화원이 되지 않도록 설계되어야 한다. 내압방폭 구조의 설계는 전기 스파크를 발생시키는 부품을 가진 용기가 내부에서 가스나 증기의 폭발시 최대 압력에 견디고 내부 화염이 외부 가스나 증기 폭발로 전파되지 않도록 설계되어야 한다. 이 논문은 화염 틈새를 통해 외부로 분사되는 연소 생성물의 분사가 외부 가스나 증기를 점화시킬 정도의 온도나 에너지를 가질 수 없도록 하는 MESG(Maximum Experimental Safe Gap)의 중요한 물리적인 메커니즘에 대해 설명하였다. IEC 60079-20-1:2010 기준에 의해 프로판과 아세틸렌의 MESG를 실험하여 MESG 값을 측정하고 가스폭발시의 최대 폭발압력을 측정하였다. 결과로는 최소 MESG가 측정될 때 가스의 농도는 화학당량 농도보다 높고 폭발압력은 최소 MESG에서 가장 높게 나타났다.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권1호
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• pp.128-134
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• 2012

This paper gives an overview of the requirements for electrical equipment in potentially explosive atmospheres and describes how these are applied to electrical machines and drives in hazardous areas. The method by which equipment can be shown to be safe in a whole range of gases, by testing in a single test gas, is covered. It is shown how the more recently introduced methods of protection for hazardous areas, increased safety and nonsparking, are ideally suited to AC machines and drives. A novel method of measuring the fullload temperature rise of electrical machines for hazardous, and other areas, without the need to connect a mechanical load to the machine's drive shaft is explained.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1394-1397
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• 1995

In the hazardous areas where explosive 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, nine types of protection have been specified in the government regulations at present: flameproof enclosure, pressurization, oil immersion, increased safety, intrinsic safety, non-incendive, sand filling, encapsulation, and special types. Among these types, the intrinsic safety has the construction which limit or by-pass igniting the electric energy using electronic devices. This type has lots of merits but at the same time requires a high-degree of technology. In this paper, we investigated several dominating factors which affect the minimum ignition energy: this energy plays a very important role in design and evaluation of the intrinsic safety type electrical apparatus. Eletrode material, which is one of the most important factors, was intensively studied for the five sorts of material(Al, Cd, Mg, Sn, and Zn) with performing experiment in a low-voltage inductive circuit using IEC-type spark apparatus. The experimental results show that the minimum ignition energy of electrode material is varied: highest in Cd and lowest in Sn. We also confirmed the effect of eletrode make-and-break speed and magnetic field magnitude.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.110-113
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• 1994

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.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권1호
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• pp.67-71
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• 2014

The well tightness of the coal mining water-cooling explosion-proof motor results in difficult heat dissipation, high hydraulic pressure is needed to increase the cooling effect. However, high hydraulic pressure may lead motor shell to deform, which makes it difficult to change the motor and maintain the motor unit. The method of adding keyhole caulk weld spots on the outer cooling water jacket was proposed to solve the problem. Based on the elasticity mechanics equations and the principle of finite element method the stresses and the deformations of the traditional and novel outer cooling water jacket were calculated separately. A hydraulic pressure experiment of the both cooling water jackets was constructed. Obviously, the stress and the deformation of the novel cooling water jacket are lower. The experimental result is consistent with the simulation results. It is effective to reduce the stress and the deformation of the cooling water jacket by adding the keyhole caulk weld spots.

• 한국안전학회지
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• 제27권3호
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• pp.63-70
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• 2012

In the hazardous areas where explosive gases, vapor or mists exist, electrical apparatus and installations must be the explosion-proof construction to prevent or limit the danger of the ignition of potentially explosive atmosphere. In Korea, nine types of protection have been specified in the government regulations at present: flameproof enclosure, pressurization, oil immersion, increased safety, intrinsic safety, non-incendive, powder filling, encapsulation, and special types. Among these types, the intrinsic safety has the construction which limit or by-pass igniting the electric energy using electronic devices. This type has lots of merits but at the same time requires a high-degree of technology. In this paper, we investigated several dominating factors which affect the minimum ignition energy; this energy plays a very important role in design and evaluation of the intrinsic safety type electrical apparatus. Electrode material, which is one of the most important factors, was intensively studied for the five sorts of material(Al, Cd, Mg, Sn, and Zn) with performing experiment in a low-voltage inductive circuit using IEC-type(International Electro-technical Commission) spark apparatus. The experimental results show that the minimum ignition energy of electrode material is varied: highest in Cd and lowest in Sn. We also confirmed the effect of electrode make-and-break speed.