Arc voltage for arcing faults on 25(28)-kV cables and splices

Hazards to people and property due to arching faults on medium-voltage underground cables and splices are related to the arc power dissipated in the environment by the arc. If the fault current may be accurately predicted from known circuit parameters, the arc voltage needed to evaluate the arc´s power has no analytical expression due to the fact that the arc resistance is nonlinear. The arc voltage is also strongly dependent on the inherent physical properties of the faulted equipment, so that in order to establish the arc voltage value and shape developed by different currently used types of equipment, a series of staged tests was performed at a high-power laboratory, and other available data were collected. The results prove that for arc power calculation purposes the arc voltage curve may be considered flat-topped and of constant amplitude specific to the type of faulted equipment.<>