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Charts of Field Tests on Air Breeze

Wind-Works.org
December 27, 2009
by Paul Gipe
http://www.wind-works.org

We have operated an Air Breeze BR0001068 since December 2007. The turbine has performed well without any problems and significantly quieter than previous versions in the Air series of micro wind turbines. The following summarizes power curve measurements on the Air Breeze.

In December 2009 we replaced Second Wind's Nomad 1 data logger with a Nomad 2 data logger as part of a general hardware and software upgrade. For more on this see Wulf Test Field Equipment Description.

Second Wind's Nomad 2 data logger is more sophisticated than the earlier Nomad 1 and it took me several weeks to get the bugs out of our installation. We may still not be out of the woods, but it appears we have our first power curve.

Below is a series of charts resulting from our tests of the Air Breeze. We begin with the most recent data and work backwards to the measurements taken in late 2007.

Note that with the Nomad 2 we have switched to metric, so the x-axis scale is in different units from those tests with the Nomad 1.

Also note that since the unit was installed Southwest Windpower has rerated the turbine from 200 W to 160 W. The latter appears more accurate based on our measurements in Tehachapi.

Again the blue square is the rated power. The rated power was originally 200 W at 28 mph.

There is another anomaly. The power curves made earlier show the turbine reaching a peak of 175 W at 24 mph. The current measurements show the turbine reaching about 150 W at 10.5 m/s. There is no simple explanation for this.

Measurements in mph with the Nomad 1 used a different data configuration for the Maximum anemometer. For the Nomad 1 tests, we used NRG's recommended slope and offset.

Measurements in m/s with the Nomad 2 used Second Wind's recommended slope and offset.

All other equipment and settings remained the same.

The difference shown here illustrates the difficulty of replicating power curve measurements without full knowledge of the equipment used and the specific data configuration used.

The Nomad 2 also reports the time series data in a slightly different manner than the Nomad 1. Though both use 1-minute averages, the scatter plot for the Nomad 2 has averaged three 1-minute samples together. The data is there but the averages are reported in the time series.