The NRG Systems Class 1 anemometer is a ball-bearing version of the industry-leading NRG #40C anemometer and was designed in direct response to customer requests

The NRG Systems Class 1 anemometer is a ball-bearing version of the industry-leading NRG #40C anemometer and was designed in direct response to customer requests for Class 1A compliance to IEC-61400-12-1. Exceptional field testing results reinforce confidence in both reliability and repeatability of the data.

For wind resource assessment projects requiring an anemometer with independently-verified Class 1A compliance, the NRG Systems Class 1 anemometer is the ideal, low-cost solution.

The revolutionary, patent-pending, dual shaft design protects the bearings from debris and common impact loads experienced in harsh climates, which further extends the life of the anemometer.

NRG Systems is the first company to obtain endorsement in the classification of an anemometer from Troels Pedersen of the DTU Wind Energy Department.

A MEASNET calibration certificate verifying the anemometer meets the standards and recommendations of the international Measuring Network of Wind Energy Institutes (MEASNET) is available through electronic download.


Sensor type 3-cup anemometer
  • wind resource assessment
  • meteorological studies
  • environmental monitoring
Sensor range 1 m/s to 96 m/s (2.2 mph to 215 mph) (highest tested)
Instrument compatibility all NRG Systems data loggers

Output signal

Signal type low level AC sine wave, frequency linearly proportional to wind speed
Anemometer Transfer Function
  • Refer to individual calibration report for anemometer transfer function.
  • All NRG Class 1 anemometers are calibrated per IEC 61400-12-1, Annex F.
Output voltage at threshold 80 mV (peak-to-peak) minimum
Output voltage at 60Hz
  • 12 V (peak-to-peak) typical
  • output amplitude NOT proportional to wind speed
Calibration each anemometer individually calibrated, calibration reports provided via electronic download
Output signal range 0 Hz to 125 Hz (highest recorded)
Uncertainty IEC 61400-12-1 Classification

  • Class 1.01A
  • Class 8.44B
    IEC 61400-12-1 operational standard uncertainty:
  • ± 0.06 m/s at 10 m/s for class A
  • ± 0.49 m/s at 10 m/s for class B
  • Refer to individual calibration sheet for information on calibration uncertainty.

Response characteristics

Threshold 0.79 m/s (1.77 mph) per ASTM D 5096-02
Distance constant (63% recovery)
  • 2.36 m (7.74 ft) at 5 m/s per ASTM D 5096-02
  • 2.28 m (7.48 ft) at 10 m/s per ASTM D 5096-02
Moment of inertia
  • 1.01 x 10-4 kg-m2
  • 74.5 x 10-6 S-ft2
Swept diameter of rotor 190 mm (7.5 inches)


Mounting onto a 13 mm (0.5 inch) diameter mast with cotter pin and set screw
Tools required 0.25 inch nut driver, petroleum jelly, electrical tape


Operating temperature range -55 °C to 60 °C (-67 °F to 140 °F)
Operating humidity range 0 to 100% RH


Connections 4-40 brass hex nut/post terminals
Weight 0.14 kg (0.3 lbs)
  • 3 cups of conical cross-section, 51 mm (2 inches) dia.
  • 81 mm (3.2 inches) overall assembly height


Cups one piece injection-molded black polycarbonate
Body housing is black ABS plastic
Shaft hardened 400 series stainless steel
Bearing ball bearings
Magnet Indox 1, 25 mm (1 inch) diameter, 13 mm (0.5 inch) long, 4 poles
Coil single coil, bobbin wound, 4100 turns of #40 wire, shielded for ESD protection
Boot protective PVC sensor terminal boot included
Terminals brass

The NRG #40C Anemometer and NRG Class 1 Anemometer employ two (2) pulses per revolution. This Application Note demonstrates the two (2) pulse count per revolution design does not result in a bias in the mean wind speed nor its variance.

NRG #40C Anemometer and NRG Class 1 Anemometer Pulse Count per Revolution.pdf

Have a question? Need help configuring and testing your NRG equipment? We're here to help. NRG Systems products come with five resources for technical support.

Product Documentation

Begin by reviewing the documentation we've prepared.

  • Read the manual: The answer to your question may be right there. Please help us to help you more effectively and read through your product's owner's manual first.
  • Application Notes or Reference Guide: Need more information about a specific product? Details about specific situations or settings can be found in the application notes.
  • Software Downloads: Just need to quickly check for a software update? This is the right place.
  • Check out the Knowledge Base: Find answers and solutions to common questions here. This is a constantly evolving database, so check it often for the latest and greatest information.


There's a good chance you're not the first person to have a specific question or issue. Check out our online Tech Forums where others like you go for answers. And if you feel you have something to offer, we welcome you to join in the discussion.

  • Search the Forums: Take a minute to search through our users forum. Often you'll find your question was answered before. If you don't find your answer, feel free to register and post your question.
  • Login to the Forums: Already a member of the forums? Welcome back!
  • Join the Forums: Ask questions, get answers and read suggestions from other customers on the NRG Tech Forums.


If you have checked the documentation, forums, and Knowledge Base and are still having problems with your equipment purchased within the past two years, you will need to contact NRG for a RMA return authorization number to return a defective product. This is the quickest and easiest way to get you back to doing what you are trying to do, measure the wind. Please see NRG Warranty for warranty details and instructions.

Repair Service

If you should need to return an out-of-warranty item for repair, please contact NRG in order to obtain an RMA number. Detailed instructions for returning an item to NRG can be found in the document Returning_Repairs_to_NRG.pdf.

Contact Technical Support

If you've explored all of the above resources and still have questions, we have a crack team of professionals waiting to answer your call or email. We ask that you be sure to use the tools above before contacting us, and we will do our best to assist you.