"Electrical
Arcs and Blasts:" by: M. McClellan
biomassman@hotmail.com"Electrical
Arcs and Blasts:" by: M. McClellan
biomassman@hotmail.com
Electrical arcs and blasts are a potential danger in any electrical device. These two items will occur if the electrical equipment is subject to certain conditions. The electrical arc is extremely dangerous because of the heat and light that is generated. The heat of an electrical arc can exceed 10,000 degrees Farenheit. The surface of the sun is 9,000. Although the electrical arc happens very fast the heat generated is very devistating. Along with the arc is the blast. These blasts are created by the superheating of the air that the arc causes. An electrical blast is essentially a bomb. Voltage and distance from the main power supply will determine the magnitude of the arc and blast. Hence the higher the voltage and shorter distance to the main power supply will create a greater arc and blast. An arc is created by a short circuit situation whether it be between two or more phases or to ground. The most common is short circuits between phases, usually caused by tools that are not insulated. When this occurs the air between the phases becomes a conductor and it uncontrollably looks for the nearest path to ground. A relatively small arc can grow into an arc that consummes the entire work area. When an arc occurs a blast is usally associated the blast is caused by superheating the air. The air expands rapidly and dissipates in all directions. For example, if the blast occured in a power panel it has only one place to go and that is out the front where you are probably standing. So you are right in the path of the blast. Also the heat that is generated can melt metal in a matter of milliseconds. Now you have shrapnel flying at you. All this happens in about half a second. There are many personal protective devices out there designed to protect you from these hazards. These devices include flash suits, face sheilds and gloves. Depending on the equipment and voltage you are working with will determine the severity of an arc if it occurs. There are mathematical formulas you can use to determi
Short circuit current= (KVAx1000)/(Transformer secondary voltage)x100%/impedance. I know from experience about arcs and blasts so please be careful out there.
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