NRG #40C Anemometer and NRG 200p Wind Vane - Calibration

[Paul Turner]

We have the above two sensors, purchased in 2009.  They are rarely used and have relatively little "field time" spending most of their life inactive (no power to the data logger) in a dark cupboard.

Should we be thinking about getting them recalibrated (especially the anemometer) from time to time if so who and how?

On another note: I took the kit out of its dark room this week and decided to test the Wind Vane, for quite a while it seemed to have problems detecting north (giving steady but apparantly random other directions when set back to north), I would manually set the heading to north, start data logger, then every few minutes change the heading through W, S, E etc. and then go back to north.  It always initally found north OK, and S, E, W etc. but on return to north would give a completly different direction.  I pulled back the boot and undid and retightened the conections and I THINK it is OK now (based on one test), but feel a little short of confidence - any comments.

 Many Thanks froma  wet 'n windy Scotland

[David Carlson]

 It sounds like your application deviates a bit from the norm (sensors permanently mounted on a mast in the field). If the sensors are handled with care and only used in short bursts they should continue to operate properly for many years. Exposure to ice, extreme winds, dust and coastal environs (salt) will contribute to the sensors' decline. Testing information for both sensor types can be found in the Knowledge Base section of our website:

http://www.nrgsystems.com/TechSupport/KnowledgeBase.aspx?id=4&category=16

http://www.nrgsystems.com/TechSupport/KnowledgeBase.aspx?id=2&category=16

If you would like to have the anemometer post calibrated (re-calibrated) you can contact Technical Support for an RMA: support@renewableNRGsystems.com. 

The 200P wind vane has a dead-band around north. Because it uses a continuous-turn potentiometer to produce a signal there exists a gap in the wiper. This small gap is the dead-band where readings may be spurious. Depending on the data logger you are using (as in, if it is not for wind resource assessment) you may want to use a pull-down resistor on the order of 1 M Ohm to clean up these readings.

The dead-band gap is specified as being no more than 8 degrees, centered on north. This is typically more like 4 degrees.