In recent power system, Continuity of Power transmission line is most challenging work for every engineer. Different types of fault occurred in transmission line. Here we learn about Transmission Line fault due to Bird.
Transmission line tripped during a particular rainy day. But during next charge, the line stood OK and catered load.
Tripping Observation
Transmission line connected between two grid substation. Both substation have interconnected power supply. During rainy atmosphere line trip in phase to ground fault. After few minutes, Line trial taken from source end and line charged.
Line patrolling summary
On next day, Line patrolling carried out. During patrolling, Line charged from both end. After line patrolling, abnormality not found.
But at the declared distance zone, obtained from the fault record of the distance protection relay at the grid station, it was observed with few bird nests exactly on the top of line insulator on the cross arm.
The places of bird nest were investigated and found with one nest being scattered with sticks and other nest material on the insulator. This might be the culprit, causing the reduction of creepage and also the arcing distance.
So during drizzle rain the nest material being hung from the nest resulted of the fault.This fault was of transient in nature, for which closure on the next attempt became successful. After closing, the line was also allowed for availing load on this line.
Action taken
The line was availed with shutdown for clearing of the nests. During clearing of the bird nest it was also found with few aluminum wires on the nests. The cause of availability of Aluminum wires were investigated.
On inquiry it was confirmed that another nearby line had been attended with mid-span joint work on the ACSR conductor due to the conductor snapping. The Aluminum wire residues were left scattered at the work place instead of gathering and brought back to safe storage.
The area nearby was also cleaned and rest of the wire residues were collected and kept in the store. The line was again charged, stood OK and loaded as per the requirement.