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NEW SYSTEM PERFORMANCE
The system is fully automatic, in any mode
selected, responding to varying wind strengths and to changes in demand,
without supervision. There is a built-in priority to minimise diesel
operation and diesel fuel consumption. The new system was brought into
service in stages until fully functioning in March 1998, and continues in
service.
The performance of the system is simply
explained by the monthly record since it was formally handed over to the
island operators in March 1998. This is set out in
Table 3. The first column
headed `start' covers the period of operational running during commissioning
and familiarisation for the operators. The service history hour meters for
diesel, turbines and synchronised were not added until the end of February,
hence the low readings! The `Year' column is for April to March and the
`Total' column is from March 1998
to date. There are one or two anomalies in the figures due to readings from
the totalising
meters being read late, but the
cumulative figures are believed to be accurate.
There have been a few outages
on both turbines but these are not
represented by the available hours subtracted from the hours in the month.
There are some wind directions
which influence one turbine more than the other, and if the power is good on
one turbine and varying considerably on
the other the affected turbine may be shut down.
One other factor which adds to the
diesel generating hours is the recent arrival on the island of some `green'
washing machines which will not work if the supply frequency varies more
than one cycle per second from 50 Hz. This problem has been solved by one
morning of diesel fed service power each week. The islanders have, as usual,
adapted very quickly to the new scheme, as is evident from the consumption
figures.
The islanders have now formed a company to
own, operate and maintain the system and the National Trust for Scotland has
passed the ownership of all the equipment to the new company. We wish them
well.
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