Author Topic: VP2 anemometer break-in interval?  (Read 629 times)

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Offline vreihen

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VP2 anemometer break-in interval?
« on: March 22, 2018, 08:50:34 PM »
Does anyone know if a new VP2 anemometer and wind vane have a known break-in period before they loosen up?  I just mounted one next to my two other weather stations, and it seems to be reading 1-2 MPH lower than the others in sub-8 MPH winds.  I can see from the ground that the cups are a bit hesitant to start spinning compared with the other two stations, and the vane likewise hesitates to change direction in variable winds.  Just wondering if this is normal for a brand new sensor, if I should take it apart and do some maintenance, or if being exposed to tropical storm force winds clamped to my car for an hour will help it rotate more freely.....
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Offline vreihen

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Re: VP2 anemometer break-in interval?
« Reply #1 on: March 23, 2018, 06:44:15 AM »
The gusts seem to be in line with the other two stations, so there isn't a problem with the cups once they start spinning.  There just seems to be some stiction and hesitation to move at low wind speeds.

Guess I'll just let it ride for a few weeks, to see if it loosens up with some additional spinning time and warmer temperatures.....
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Offline ValentineWeather

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Re: VP2 anemometer break-in interval?
« Reply #2 on: March 23, 2018, 07:54:12 AM »
No break in period, I have heard different anemometer brands can be more or less sensitive with very low wind speed.
Randy

Offline vreihen

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Re: VP2 anemometer break-in interval?
« Reply #3 on: June 24, 2018, 08:15:54 AM »
As a follow-up in case anyone searches this in the archives, both anemometer and wind vane did finally lose their stiction and start spinning much more smoothly after a few months.  I suspect that some highway driving attached to my car would have expedited the break-in period, but did not test the theory myself.....
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Offline miraculon

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Re: VP2 anemometer break-in interval?
« Reply #4 on: June 24, 2018, 08:34:40 AM »
I have an R M Young Wind Monitor (jr.) on the same mount as the VP2 wind set. The Young is way more sensitive both in terms of the vane response and the anemometer (propeller). I will see the Young vane moving around and the propeller happily spinning in light wind and the VP2 is as dead as a doornail.

The Young starting threshold is 2.2 mph (1m/sec). The VP2 claims the same, so from the behavior maybe my 2011 vintage wind set is due for replacement. (a major pain...)

Greg H.


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Offline dcriner

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Re: VP2 anemometer break-in interval?
« Reply #5 on: June 30, 2018, 06:25:54 PM »
Perhaps others are like me - I'm not too concerned about very low windspeeds. But, give it a few months.
Doug

Offline wxtech

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Re: VP2 anemometer break-in interval?
« Reply #6 on: July 15, 2018, 11:27:36 AM »
I agree with Greg, Miraculon.  I frequently notice the RMY spinning and twirling while the Davis is still.  If you open the VP2, on the direction shaft you'll notice a brass bushing and one ball bearing.  Davis uses one brass bushing and one ball bearing supporting the cups. 
The direction vane shaft is the direction potentiometer shaft.  It has a wiper that contacts the resistance element, hence a mechanical opposition to movement.  The vane needs to have opposition to direction change so that a puff of wind won't cause the vane to go round-and-round.  It should gently move to the new direction without overshoot.
More information is here:  http://www.lexingtonwx.com/anemometer/
Al Washington, Lexington, Ga.,  NWS Coop station=LXTG1, Fischer Porter, SRG, MMTS. 
CoCoRaHS=GA-OG-1. CWOP=CW2074.  Davis VP2+ WLIP 5.9.2, VP(original) serial, VWS v15.00 p02. ImageSalsa, Win7 & Win8 all-in-one.

Offline vreihen

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Re: VP2 anemometer break-in interval?
« Reply #7 on: July 15, 2018, 06:04:03 PM »
Both vane and cups both freed themselves up quite nicely after a few months, and the VP2 is now the first one to spin on calm air days.  It is even tracking the ultrasonic unit that it shares the mast with nearly identical down to 1 MPH, so there was some stiction out of the box that went away after it broke in.....
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