EoW March 2012

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EuroWire – March 2012 187
Technical article
Poor quality equipment, even though
having a lower initial cost, can lead to
higher maintenance (such as repeated
failures) and replacement cost, due to
shorter than expected life-cycle.
Use of either water barriers or TR-XLPE
materials in cable design will increase the
cost of finished cables.
The additional cost of cables must be
justified via rigorous financial analysis.
LCC has been applied recently by utilities
to evaluate the procurement of new
equipment.
Although the initial cost of TR-XLPE cables
is estimated to be slightly higher than
XLPE cables, LCC analysis demonstrates
that the value of TR-XLPE cables far
exceeds the initial cost increment over
XLPE cables, due to the significant
cost savings achieved with a longer
performance life and higher reliability.
A model has been created to compare the
LCC of XLPE and TR-XLPE cables, using the
various cost inputs as shown in Table 3.
Initial cable cost was estimated based on
copper price of US$9,500/MT.
TR-XLPE cable was assumed to cost 5%
more than standard XLPE cable, based on
differences in price of XLPE and TR-XLPE
materials. Number of cable failures prior to
total cable replacement (between joints)
can be adjusted.
Installation cost of replacement cables
can also be adjusted as needed. The
failure cost shown only accounted for the
repair cost of the cable failure and did not
include loss of revenue.
However, additional cost associated with
power loss due to cable failures can be
included in the model.
To enhance the accuracy of computation,
more than two life-cycles are used in the
LCC analysis.
For example, consider the situation after
75 years – the XLPE-insulated cable will
have been replaced twice whereas the
TR-XLPE insulated cable will only have
been replaced once. The model computes
the net-present-value (NPV) of total cost of
each cable.
Tabulated in Table 4 is the computed total
cost difference of XLPE and TR-XLPE cables
of various life-cycles.
For example, when comparing a XLPE
cable with a life-cycle of 30 years and
a TR-XLPE cable with a life-cycle of 40
years, the LCC difference between them is
USD$64,965/km, meaning the LCC of the
XLPE cable is $64,965/km more than the
TR-XLPE cable.
This is due to the higher maintenance
and replacement cost of XLPE cable
as compared to that of TR-XLPE cable
because the life-cycle of XLPE cable is
shorter than TR-XLPE cable, even though
XLPE cable costs 5% less than TR-XLPE
cable initially.
Conclusion
Until testing standards are specified for
distribution power cables, stakeholders
across the value chain should take it
upon themselves to be aware and make
decisions that will ultimately deliver
long-term value and reliability.
Specifiers should become familiar with a
variety of materials that are proven to offer
the benefits needed by their companies
and their consumers.
Testing facilities, cable manufacturers and
materials suppliers should work more
closely to make this information easy to
understand and to access.
Ultimately, there may be global standards
that will further encourage this kind
of partnership and teamwork that will
benefit the entire industry as well as the
consumers of energy. n
Dow Electrical and
Telecommunications – USA
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