POWER December 2014 - 42

Wind PoWer
8. Typical OEM windings. Courtesy:
Shermco Industries
9. New windings during remanufacturing. Courtesy: Shermco Industries
common run-to-failure strategies. Troublesome
turbine models are now often managed
through long-term maintenance contracts
with the turbine OEMs, shifting the major
component risk to lowest cost sourcing.
Up-tower generator repairs, which now
include almost anything that does not require
removal of the generator rotor, are quite commonplace
and are being performed more often
by the local O&M entity. There is a risk,
of course, in this method, as warranties do not
cover self-performed repairs, but basic minor
component replacement, such as brushes or
cooling unit blower motors, is normal. More
critical procedures, such as bearing replacement
and rotor re-leads, should still be left to
technical specialists due to the risk of further
damage to the generator if the repair is not
performed accurately. Saving a little money
on a bearing change seems like a good idea,
but an improper installation can result in a
spectacular failure of both the rotor and the
stator, and the cost of that risk should always
be considered, as most specialty service
companies provide some level of warranty
for labor and materials.
Here are some generator reliability observations
if you are considering self-performing
O&M on a wind project.
Many business models are utilized for
overall wind project maintenance. All have
their merits. As with many utility installations,
some project owners want to do it
all, while others want to shift the risk to the
equipment OEM or to a third-party O&M
group. Often, the owner manages the highvoltage
systems and grid interconnect and
controls large component repair or replacement.
Regardless of who has the responsibility,
the maintenance strategies should be
42
transparent and include a good process for
controlling the quality of replacement and
remanufactured components (Figures 8,
9, and 10). Knowing the historical failure
modes for your specific turbine model and
knowing what procedures are in place to
correct the problem, either from the OEM
or from a specialty service provider, is the
best way to protect your assets from ongoing
issues.
Understanding that the loss of magnetic
wedges is a prime culprit in many prewww.powermag.com
mature
failures, make sure that the OEM
has found the manufacturing solution on
replacement components rather than just
putting a new unit with the same weakness
into service, even if the turbine is still
under warranty. For aftermarket suppliers,
ensure that they clearly understand the issue
and have developed system designs
that solve the problems for the long term,
not just their warranty period.
Other failure modes can also be mitigated
during a remanufacturing process. The comPOWER
| December 2014
10. Windings after remanufacturing. Courtesy: Shermco Industries
http://www.powermag.com
POWER December 2014

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