The amount of damage that can be caused by electrical arcing events continues to be an important question for both new and legacy aircraft. Many factors can affect the damage done by arcing events. For example, events occurring a short distance from a power bus can have much higher currents and power than those a long distance from the bus. Other important parameters include voltage, target material and geometry, circuit protection, separation, wire gauge and specification, initiation method etc.
In work initiated by the FAA, Lectromec has begun the development of an arc damage modeling tool. The tool will be based on both analytical and empirical data and will use the concepts of energy quantification and heat transfer. The types of damage to be modeled by the tool include: damage to the source (wire) and primary target (hydraulic line, flight control cable, structure, etc.) as well as other wires in the bundle and objects at a distance. Over 600 arcing tests have been performed with varying physical and electrical conditions that would likely be experienced on in-service aircraft. The resulting damage to the arcing target and wires in the test bundles have been measured as well as the power and energy dissipated in the arc. This data has been compared with arcing data previously generated by the FAA Tech Center. Analyses of both sets of data have identified how variations in physical and environmental parameters affect the resulting damage.
If you would like to read more on the topic of arc damage, you can read Lectromec’s Impact of Series Arcing article.
One standout piece of information presented is the damage at a distance. The use of the wire strand mesh and target wires placed above an arcing wire bundle proved effective in determining the effective damage radius of the arc plume. Tests indicate a damage distance of between ¼ and ¾ inches. Profiles of the arc plume were also captured with this method. The image and video below describe some of the results of this analysis.