Case studies · Recurrent faults
Two blinks a day apart led to a charred crossarm beside a pine forest
Nobody lost power for more than a blink. DFA matched the two faults, and the crew found a conductor burning into its crossarm six spans from the prediction.
- Utility
- Mid-South Synergy
- DFA reported
- Two matching faults about 24 hours apart
- Circuit
- Rural 25 kV, 109 miles of exposure
- Found
- Six spans from the predicted location
- Outcome
- Repaired in fair weather before any outage
What DFA reported
A broken insulator let a phase conductor drop onto its wooden crossarm. The first flashover tripped and reclosed a mid-point recloser. About 24 hours later a second fault did the same. Customers saw two blinks, and ordinarily nobody would have gone looking. DFA reported both faults from the substation.
What the crew found
The engineer who reviews DFA reports saw that the two faults matched in phase, current, duration and recloser response. He entered DFA's fault current into the circuit model and used the branch reclosers' records to choose between two candidate locations. A directed patrol found the displaced conductor and a heavily charred crossarm six spans from the prediction.
Why it matters
The co-op made the repair in fair weather. Left alone, the arm or the conductor could have burned through: a sustained interruption, a pole-top fire, or a live conductor on the ground beside dry underbrush and pines.
Keep reading
Six faults in nine hours, no outage, no calls, and a branch removed
A hanging branch tripped a recloser six times without an outage. DFA grouped the faults into one report, and a targeted patrol found it.
Same fault twice in six days, and a dead squirrel found within hours
A breaker trip interrupted more than 1,200 customers twice. DFA linked the two faults within a minute, and the report took the crew to one pole.
Two blinks in 18 days, and a failing arrester found within four spans
On a 125-mile circuit with about 20 unmonitored reclosers, DFA showed which recloser was working and cut the search area by 76%.