There are 6 reasons to explain this.
1. Asset management
FRP
cross arms can be manufactured in relatively short order, providing
quality structures in the large quantities utilities need.
The
current lead time is as low as 3 weeks. This is in contrast to the over
6 month wait for industry-quality steel for electrical applications.
2. Cost savings
The
largest expense in replacing wood or steel cross arms is the cost of
time to send the crew to the installation site. Installation can be
particularly expensive if the only way to access the site is by
helicopter, due to rough terrain.
Installation
costs are required to replace wooden cross arms every 25 to 40 years,
depending on environmental conditions and the original quality of
timber. Meanwhile, FRP cross arms provide the possibility to skip up to 2
of the replacement cycles required by wooden cross arms as they enjoy a
life expectancy of over 75 years. In overall life cycle cost analysis,
this represents a significant savings.
3. Environmentally safe
In a world where environmental concerns are becoming a key issue, the minimal environmental impact of FRPs are attractive.
FRP made with fiberglass chopped strand mat,
cross arms are environmentally inert as there is no leaching of
chemicals into the environment. Because of this, some environmental
groups are embracing the use of FRP structures in
environmentally-sensitive areas like bogs and wetlands.
In
the case of disposal, nothing from the FRP cross arms will contaminate
the environment and as such FRP cross arms can be recycled (preferred
option) or placed in a general landfill.
4. Durability
FRP
cross arms are also a very durable choice in warm, high humidity
environments where treated wood does not last very long and steel
corrodes very quickly.
FRP
composite cross arms and also proved the viability of FRP cross arms in
showing resistance to lightning strikes, bearing structural loads well,
and long term durability.
5. Raptor & environmental protection
In
some areas, raptor protection is a particular concern. When these birds
land on energized steel transmission cross arms, their long wingspan
can bridge over the distance between the conductor phases and metal
cross arms, causing injuries and potentially loss of wildlife. When this
happens, utilities have to pay significant penalties; it is also a
public relations challenge.
With the electrically non-conductive nature of FRP cross arms, such accidents and issues are preventable.
6. Long term performance
Using new materials and components always raises questions about long term performance.
As
mentioned above, accelerated aging tests performed by an independent
laboratory confirmed that two component polyurethane composite cross
arms have an expected life span of over 75 years. This is significantly
better than the expected life span of wood cross arms and galvanized
steel (with no additional corrosion intervention once the galvanized
coating is gone), which is about 35 years in most urban environments.
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