Niche Market TESTING
By Ly n n Ha mr ick ,
Shermco Industries
Testing For Rural
Electric Cooperatives
The Rural Electrification Act of 1936 provided
federal loans for installation of electrical
distribution systems to serve rural areas of the
United States. The funding was channeled
through cooperative electric power companies,
most of which still exist today. These memberowned cooperatives purchased power on a
wholesale basis and distributed it using their own
network of transmission and distribution lines.
These rural electric cooperatives (RECs) still rely
heavily on the federal government for funding
through an electric program administered
through the United States Department of
Agriculture (USDA). Loans are made to
corporations, states, territories and subdivisions
and agencies such as municipalities, people’s
utility districts, and cooperative, nonprofit,
limited-dividend, or mutual associations that
provide retail electric service needs to rural areas.
Through the Electric Programs of USDA, the
federal government is the majority note holder
for approximately 700 electric system borrowers
in 46 states.
To be compliant with USDA requirements, the
USDA issued Rural Utilities Service (RUS)
Bulletin 1724E-300, Design Guide for Rural
Substations. The latest issue of this bulletin was
in 2001. Additionally, RUS Bulletin 1724E300 provides details that RECs must meet with
regard to electrical testing requirements for
their substations. These requirements include
combinations of visual inspections, electrical
tests, and other periodic maintenance activities.
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SUMMER 2011
S u bstat i on Inspec t io ns
To ensure power system reliability, it is essential
that inspections of substation equipment,
structures, and other devices be made
periodically. General guidelines for the required
inspections for substation equipment, structures,
and other devices are discussed below. They
should be tailored to meet the requirements of
a specific site as well as for the equipment at the
site. Visual inspections should be performed
and should encompass the total substation
including the control house and all equipment
and structures. This inspection should be
performed with the substation energized.
Therefore, all inspections should be made from
ground level to ensure adequate safety clearances
from energized parts. Binoculars may be used
to view buses and other equipment located on
structures. Since a high voltage could develop
across any gap created between a ground cable
and a piece of equipment, particularly under
fault conditions, special care should be used
when ground connections are inspected. For
this reason, ground connections should not be
removed for any reason while the substation is
energized.
In addition to these periodic inspections, other
predictive maintenance tests may be required
to ascertain the cause of particular problems,
when equipment is placed in service or when
the substation, or portions thereof, are taken
out of service. The attached Table 18-1 from
RUS 1724E-300 is provided for information.
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