Criteria about third party sensors

[Andres]

I'll give you a criteria according to my experience of working simultaneously with NRG and THIES sensors. I ran a wind prospecting network of over 80 masts of 50 m each, in Cuba, and I installed my self over 50 % of them. One thing that favoured your plastic cover anemometers against the THIES' anodized aluminum body is the lightnings. I had, 'till date, 5 anemometres that were literraly stocked by indirect lightning stroke, the bearing got virtually melted. This is something that naver happended with NRG anemos. But, I've notice that NRG anemos have a bigger inertia than THIES ones, at the moment of start running, like if the bearings of THIES had less friction, and this is something quite interesting, that I've found in a mast in which i installed both systems. 

[David Carlson]

 Andres, good information, thank you! 

I just wanted to point out that while the Thies may have a slightly lower moment of inertia, the NRG MAX #40 will reach linearity by the time wind speed reaches 4 m/s.  Any speeds lower than this are of little concern with respect to wind energy, because there is essentially not enough energy in the wind for production. 

All the best,
Dave 

[johng]

NRG
released the NRG Class1 sensor last year, which contains an innovative low
friction ball bearing design providing very good response
characteristics.  In fact, the NRG Class1 is a true ?class 1? sensor at a
very attractive price.  The NRG Class 1
kept the rugged cup design of the NRG #40C anemometer, as well as the proven shielded
signal pick-up mechanism.

I
cannot say for certain that other sensors fail more easily than the rugged coil
design of the NRG, as your experience suggests. 
Both the NRG Class1 and the  NRG
Windsensor P2546C use a self generating coil and magnet arrangement, requiring
fewer wires and no power from the data logger. 
Another great benefit of such a signal arrangement is that even under a
direct lightning strike, the sensor will not fail as a short (signal coils fail
as an open circuit), and the remaining channels keep logging data until you can
visit the site.  The WindSensor has excellent
first class performance characteristics, the lowest distance constant of any
cup anemometer in existence, as well as superior off shore capability.

You
can read about the NRG Class 1 classification in the paper ?Characterization and Classification of the NRG Class 1 Anemometer
for IEC 61400-12-1 Compliance? found on the NRG Class 1 product page.