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Multiple electric power service
interruptions have occurred in the vicinities of DeLeon and Gorman
communities over the last several months. A large number of these
interruptions are attributed to factors related to the Oncor (TXU)
owned transmission lines that serve these communities.
Lightning strikes and birds making
contact between one of the power line phases and a non-energized part
of the transmission structure have accounted for a significant
majority of the recent outages.
Lightning strikes cause high levels of
current and voltage rise on the transmission system. Large birds, such
as vultures, can also come into contact with energized facilities and
create electrical faults to ground with their wide outstretched wings.
Both of these actions result in operation of the strategically placed
protective breaker equipment on the transmission line.
These breakers protect the transmission
equipment and operate similarly to the breakers in the breaker box in
your home. Transmission breakers are designed to momentarily stop the
flow of electricity to clear the fault, if possible, and return the
flow of electric service within a fraction of a second. Transmission
line faults that do not clear during the normal operation of a breaker
will cause a prolonged outage until the cause of the interruption can
be determined by the transmission line owner.
Oncor Electric Deliver, owner of the
transmission line, has been contacted on numerous occasions to
facilitate repairs and modifications to reduce the number and
frequency of power interruptions occuring to their transmission
facilities in the area. They report that they are making efforts to
identify the locations of the problems and to implement modifications
as time and budgets permit.
Some of Oncor’s modifications include
changing the line insulators from porcelain to polymer materials and
installing bird protection devices to lessen future occurrences of the
power outages. Oncor engineers are also looking at line design
improvements to determine what can be done to reduce the effects from
lightning strikes.
Installation of polymer insulators
provides approximately eight inches of additional line clearance and
thereby reduce the likelihood of a bird making contact between one of
the phases and a non-energized part of the structure.
The bird guards are large
triangular-shaped objects that can be positioned on the cross-arms
adjacent to the insulators. These guards have proven to deter birds
from roosting in the vicinity of the insulator and conductor when
installed on similarly constructed transmission facilities.
The line design change may take several
years to complete once the design has been approved in Oncor’s
transmission planning division.
Thanks to Ronnie Robinson of Comanche
Electric Cooperative for his assistance in providing the above
information. |
