DFA Case Studies
BC Hydro and other utilities have used DFA technology detect and locate conductor-slap events on overhead lines, enabling proactive repairs, to prevent future outages and stresses to the system. A conductor-slap event occurs when an initial fault induces magnetic forces that cause a second fault, closer to the substation, often leading to breakers tripping entire feeders.
Pickwick Electric Cooperative (PEC, Selmer, TN) used DFA technology to avoid an impending outage from tree encroachment in an overhead line. The DFA system discovered the problem, based solely on substation-based current and voltage waveforms, coupled with intelligent, on-line algorithms. It provided location information that enabled PEC to find and eliminate the encroachment before it caused a permanent outage. PEC had no other indication that a problem existed.
Cracked and burned bushings and insulators are well-known causes of interruptions and outages. DFA technology enables utilities to avert sustained outages resulting from apparatus failures, including compromised bushings. By applying intelligent, on-line algorithms to substation-based current and voltage waveforms, the DFA system detects electrical precursors and alerts utilities of developing problems. In the case of the burned bushing shown below, the utility used the DFA to discover the problem existed, locate the burned bushing, and make repairs that preempted a likely future outage. At no point did the utility receive any customer complaints related to this issue; the DFA system provided their first and only notice.