Patent ID: 8138766

Claim:
A method of producing flashover analysis signal comprising processing a neutral current, three phase voltage profile, and a plurality of digital signals of a transmission line to identify a flashover fault caused by tree encroachment, crane, polluted insulator or lightning strike, by obtaining λ, the gradient of neutral current's root mean square value, whereby; if λ is not more than a threshold value, then the fault is a tree encroachment; if λ is more than a threshold value, then determine if voltage dip is less than a threshold value; if voltage dip is less than a threshold value then the fault is also a tree encroachment; if voltage dip is not less than a threshold value, then determine if a persistent fault is found; if a permanent fault is found then the fault is caused by crane; if there is no persistent fault, then determine if Δt f is more than a threshold value; if Δt f is more than a threshold value then the fault is caused by polluted insulator; and if Δt f is not more than a threshold value, then the fault is caused by lightning strike; wherein the above-mentioned steps are not restricted by order and Δt f is the time interval between the last current distortion and a flashover.