Case studies · Recurrent faults
Two storm trips three weeks apart, one cause, fixed by trimming
DFA gave the utility its only notice that two breaker operations were the same fault, and what it was.
- Where
- Overhead circuit, United States
- DFA reported
- The same fault twice, three weeks apart
- Cause
- Branches pushing the phases together
- Found
- Conductor already showing broken strands
- Outcome
- Targeted trimming stopped the repeats
What DFA reported
Two momentary operations of the substation breaker happened during storms three weeks apart. DFA gave the utility its only notice that both were the same fault, and information to locate the cause: branches pushing the phases together.
What the crew found
The crew found the spot. The conductor already showed broken strands from repeated contact.
Why it matters
Targeted trimming stopped the momentary operations before they became lockouts, line damage or a burn-down, and the work was done in fair weather.
Keep reading
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.
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.