Analysis of a flashover operation on two 138kV transmission lines

Flashover operations due to a change in the physical positioning of a foreign object with an energized conductor are a common occurrence seen throughout many transmission and distribution systems. The inception of a fault from a flashover between two stationary conductors, however, is not as prevalent. This is primarily due to extensive protection system coordination and insulation design specifications that, under anticipated fault conditions, will allow the necessary protection devices to operate, thereby clearing the fault. For Bryan Texas Utilities during the summer of 2013, a particular flashover operation brought about a series of atypical events, which resulted in several operations involving two 138kV transmission lines as well as portions of the 12.5kV distribution system. As presented in the following analysis, it is evident that, while the fault conditions experienced by the system were not within anticipated limits, there are some steps that can be taken to mitigate future operations of this nature.