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Wind Speed Abnormality

Discussion of version 3 of Cumulus, which runs on Windows, Linux, and OS X. All Cumulus MX queries in here, please.

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Big Daddy
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Wind Speed Abnormality

Post by Big Daddy » Wed 18 Apr 2018 9:28 am

Hi All,
Not sure if this is the right section to post in but didnt seem anywhere else to put it.

My station / MX only seems to report wind speed at certain times of the day and I am confused as to why. Please see the attached MX graph.
I recently had to change the wind vane and whilst I had everything down I decided to change the anemometer at the same time as I could hear the bearings starting to grind. That was about 3 weeks ago and I didnt notice any problems up until recently.

My only possible thought is that I do have a "joint" in my cable using an RJ11 extension cable and RJ11 to RJ11 connector but its all sealed up and I was wondering if it could be temperature related as in when it gets warmer it slightly expands and starts to makes contact, or a bit of damp which temporarily dries out when it gets warmer.

I just wanted to see if there was any other suggestions before climbing up and taking down the whole mast again.

Many Thanks
Andy
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steve
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Re: Wind Speed Abnormality

Post by steve » Wed 18 Apr 2018 1:17 pm

Looks to me like a dodgy connection somewhere.
Steve

Big Daddy
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Re: Wind Speed Abnormality

Post by Big Daddy » Wed 18 Apr 2018 2:00 pm

Thanks Steve,
Sort of coming to that conclusion as well, as much as I dont want it to be as it means clambering up the ladders and taking everything down. Hopefully the weather will stay nice and I can get up there at the weekend.

Andy

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Re: Wind Speed Abnormality

Post by AllyCat » Wed 18 Apr 2018 2:47 pm

Hi Andy,

Yes your diagnosis sounds very probably correct, but a few easy things you can try first:

Windspeeds are generally lower at night so the new anemometer might just be "stiff". Is it definitely rotating at night when no wind is recorded? I presume the slightly elevated zero line on the nights of 15th and 16th is just a glitch in the graphing?

Is the Wind Direction (Vane) reporting correctly (on the Console) and not correlated with the "loss" of wind? The two sensors are generally separate but share a common earth, and note that Cumulus only records a valid wind direction when the windspeed is not zero.

If it is a "faulty contact", it might be in your "extension" cable or socket, or the plugs into the Vane or Transmitter cases, or the magnetic reed itself. Do you at least have easy access to the transmitter, and a multimeter? If so, try to check if the voltage across the anemometer switch (middle two pins of the RJ11) is swinging between zero and about 3 volts (battery voltage), or at least cleanly crossing a 1.5 volts level, when the anemometer is rotating (two pulses per revolution). Not an easy measurement with normal probes, but you might be able to open the Transmitter case or use a couple of needlework pins to make a connection to/through the cable.

Cheers, Alan.

Big Daddy
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Re: Wind Speed Abnormality

Post by Big Daddy » Wed 18 Apr 2018 3:22 pm

Thanks Alan,
Its a Fine Offset so the wind vane plugs into the anemometer then a cable from there to the transmitter. Those slightly elevated lines on 15th 16th seem to be genuine as you can see below it records a direction at that point, so Cumulus must register it as a speed reading. Normally though I would expect to see the wind speed slowly increase / decrease. This looks like somebody has turned a fan on and then switched it off.

I will get out and do some measuring, fortunately the transmitter is fairly accesible and I have a mulimeter. I can probably knock up some sort of test rig so I can measure the readings without the risk of damaging cables. Will also hope for some nights with a bit of wind so I can check if the anemometer is spinning and whats being recorded on the console.

Appreciate the assistance.
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Ned
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Re: Wind Speed Abnormality

Post by Ned » Wed 18 Apr 2018 10:43 pm

I've had similar problems with the rain gauge not reporting, and came up with a simple test circuit involving a mini piezo siren, a 9v battery and an RJ11 socket, to plug the cable into instead of the transmitter. It's so easy to hear the pips (even from a distance) as the reed switch closes than straining to detect fleeting changes on a meter. although a meter with audio continuity tester would suffice.

Big Daddy
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Re: Wind Speed Abnormality

Post by Big Daddy » Thu 19 Apr 2018 8:28 am

Thanks for all the suggestions. I noted last night when the console and MX were reporting no wind that the anemometer was still spinning.

I think the best thing to do is take the whole thing down, do some bench testing and see what I find. I have a spare transmitter as well, so new everthing, and hopefully I will be able to get things working. What I may do is also make a new correct length cable with no joins (I have the crimping tool etc.).

Trying to keep the old girl going as I dont have the funds at the moment to replace. Was hoping Maplin might have an ultra cheap replacement in their closing down sale but they are still more expensive than when they had them on offer.

Andy

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Re: Wind Speed Abnormality

Post by freddie » Thu 19 Apr 2018 11:41 am

Is your transmitter solar-powered with a battery back-up? Just thinking out loud ...
Freddie
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Big Daddy
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Re: Wind Speed Abnormality

Post by Big Daddy » Thu 19 Apr 2018 1:17 pm

Hi Freddie, no its not. Its a bog standard Maplin N96GY (Fine Offset). Its done me well for nearly 4 years so for £69.99 I dont suppose I complain. Will do my bench testing over the weekend.

I did see that Maplin have some left at £48 but there not available for delivery and the nearest one in store is Birmingham....100 miles away.

If I cant get her working at the weekend I may have to look at alternatives.

Andy

freddie
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Re: Wind Speed Abnormality

Post by freddie » Thu 19 Apr 2018 1:53 pm

Ah okay. I thought I would ask the question, though, as the on/off hours seem to be fairly consistent and coincident with when the sun was highest :D Good luck with diagnosing and sorting it out.
Freddie
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Big Daddy
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Re: Wind Speed Abnormality

Post by Big Daddy » Tue 24 Apr 2018 8:38 am

All seems to be resolved now. I dismantled everything and tested it all, all components seemed to be working. I then decided to extend the cable directly from the wind vane to the transmitter (the anemometer plugs directly into the wind vane). This however is hard wired into the wind vane so needed to dismantle, un solder and re-solder correct lenth of cable. Connected up and havent seen an issue since.

Thanks for all the suggestions / advice.
Andy

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