What is the hazard of arc in medium and low voltage panel?
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Author:hkwa49fa3
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Published time: 2019-07-01
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Arc light can not only cause the burning of insulating materials, but also cause the metal (copper row, aluminum row) to melt and splash, forming a fire source for fire and explosion. Electrical equipment itself in addition to multi-oil circuit breakers, power transformers, and power capacitors. Oil-filled equipment such as oil-filled casings may burst and generally do not explode. However, the following conditions may cause a space explosion.
1) An explosive mixture of ambient air causes space explosion under dangerous temperature or sparking.
2) The insulating oil of the oil-filled equipment is decomposed or vaporized under the action of an electric arc, and a large amount of oil mist and combustible gas are ejected, causing an explosion.
3) The generator hydrogen cooling device leaks gas, the acid battery discharges hydrogen, etc., forming an explosive mixture, causing space explosion.
The harm of arc light to people in medium and low voltage panel:
1) The intensity of the arc is about 9000 Lux, and the maximum light intensity perceived by the human eye is about 300 Lux. It is easy to stab the human eye, causing the corneal epithelium to fall off, and there are symptoms such as fear of light, tearing, foreign body sensation, and conjunctival congestion.
2) Burns caused by arc explosions are the most serious injuries, mainly from molten metal that emits a large amount of heat radiation and splashes during electric explosion; and the severe burns caused by burning and droplets of clothes after being ignited;
3) The loud noise generated during electric explosion can cause fatal damage to the hearing damage and the explosive elasticity to the human body.
4) Under the strong arc radiation, the air around the arc will also produce toxic gases such as ozone and nitrogen oxides to damage the respiratory system.
The harm of arc light to equipment in medium and low voltage panels:
As we all know, arc short circuit is the most serious fault in the distribution network, especially in the case of medium and low voltage panel. Due to the arc resistance, the short circuit current often fails to reach the overcurrent value and can not be operated quickly to cut off the fault. As a result of the continuous burning of the arc, huge energy is released, which has catastrophic consequences: the panel is severely burned. The arc short-circuit fault of the panel is often developed as a medium-voltage bus fault due to failure to be removed in time, and the hazard is very seriously, it causes the power plant to disintegrate electricity, the power outage of important users, and the more serious "fire-burning" accidents that caused multiple groups of panel to burn at the same time. In recent years, the main transformer has been caused by the huge short-circuit current impact of the busbar fault. Damage is not uncommon, and these accidents have caused significant economic losses.
