An electric arc is a jump of electricity formed by the body, which is close to the high voltage but not in contact with the body. It can produce a high temperature of 35,000 degrees Celsius, about four times the temperature of the sun's surface. When an arc occurs, great energy is released in a very short time. Metallic conductive elements vaporize, causing high temperature steam and rapid expansion of the metal. Rapid and thermal expansion of air and metal vapors causes loud explosions and great pressure.
Main forms of arc injury
1. Arc explosion burn is the most serious injury of the arc injury, which mainly comes from the thermal radiation emitted by arc explosion and the molten metal splashing.
2. Severe burn caused by arc explosion after the clothes are ignited or the clothes drop.
3. Hearing damage caused by the loud sound produced by arc explosion.
4. Physical damage to human body caused by the impact force of arc explosion.
The damage of arc to human body
Electric arc injury generally refers to the electric arc heat burn caused by human body when there is no contact with electric current. However, other electrical injuries are usually more destructive damages of internal and external human tissues caused by direct contact with the power supply current. In general, people are more aware of accidental electric shock, while in fact in the power industry more dangerous is hidden and unknown arc injuries. Unlike other electrical injuries, arc hazards are often neglected and difficult to avoid without contact. Direct contact with ignited clothing can cause severe burns or death to workers.
Measure of arc strength
The Arc Thermal Performance Value is measured in Cal/cm squared (calories per square centimeter). It refers to the total energy per unit area used to measure the strength of an arc. The exposure energy of 1 Cal/cm squared is equivalent to a lighted cigarette on the fingertips for 1 second, and only 1-2 Cal/cm squared can cause a level 2 burn to the human skin.
According to the American NFPA association, it is known that arc injuries are mainly caused by human burns caused by the heat generated by the arc explosion. Therefore, the standard to measure the possible damage caused by arc is usually the standard of arc energy, namely Cal/cm squared (calories per square centimeter). The higher the ATPV value of arc protective suit, the better its arc protective performance.