Document No. 1112M001 Revision 1.8 Date: June 2013
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are damaged in any way or show signs of deterioration over time.
Although these components are UV stabilized, this may occur in
environments with high solar irradiation.
The Generator
The Kestrel e400nb generator is a completely sealed unit and requires
no regular maintenance. The generator carries two single deep groove
bearings and one double bearing assembly. All bearings are of a high
quality and are sealed for life. The generator is a brushless single rotor
axial flux permanent magnet assembly with no less than 120 poles and
sixty-two magnets. The magnets are rare earth neodynum boron
composition. The thermal management in the generator ensures that
the temperatures never reach the Curie point. The generator will never
overheat and is rated for 100% duty cycle. This means that the turbine
is designed to produce the full rating of 3,5kW for the complete
duration of a high wind period.
Unlike many generators, the Kestrel e400nb produces dc power. There
are therefore no inductive affects in cabling and radiated emission is
absolutely minimal. The power output has a much lower ripple content
compared to a three phase system. High ripple content reduces battery
life and should be avoided.
The Transfer Brushes
A dual brush and slip ring assembly delivers generator power to the
output cables. It is located within the same assembly that supports the
complete turbine on the tower. It is referred to as the “swivel assembly”
and is extremely well designed and strong. The complete assembly is
simple to remove from the generator and can be replaced as a
complete unit. Kestrel intends in the future to provide an exchange
service for the complete swivel assembly.
There is a total of four high quality copper/carbon composite brushes,
two for +ve and two for –ve. The transfer system is well rated and
requires no replacement for many years of service. Some owners may
feel a little uncomfortable that one cannot easily inspect the brushes.
Kestrel strives to produce a wind turbine that is reliable and has a
minimal maintenance schedule.
