# User metering and fan failures



## PVGuy (Apr 22, 2017)

Dunno if this is the right place to ask, but I'll give it a try.

One of our farm customers suffered some bin aeration fan failures during last season's harvest. The fan supplier told him he's maybe running too many fans leading to low voltage / high current / burnout. No question he's guilty of running too many fans from time to time. He asked us about installing voltage and current meters on a couple of his distribution panels so that he knows when he's overdoing it.

I understand the appeal, but most of the options I've found seem mighty expensive, with unwanted RS485 or ethernet interfaces and logging and so on. This equipment is all outside so the meters would need to be suitable for direct exposure to the weather. Probably installed beside the panel in a 4x enclosure. Of course monitoring voltage at the loads would make more sense, but some of the panels are quite a ways from the CSTE so there's some validity to the idea of having some indication at the panel(s) of how things are going, more-so on the current end of things.

Can anyone recommend a source of panel meters that wouldn't be overkill or cost an arm and a leg? I've been resorting to shopping sources like Alibaba...

Perhaps the more important question is what's actually going on here. With the exception of a couple of 3-phase fans running off drives, everything is 240 V single phase. All the fans are either 7.5 or 10hp and all are rated for 208 V operation, so if voltage drop is the issue it's gotta be insanely severe.

All the fans are thermally protected. Most use the onboard "thermostat" (odd but common terminology) wired into the starter control circuit, so if they cut out on temperature, they aren't going to restart automatically. Someone has to notice, then physically go out there and restart them. Some starters incorporate an overload relay in addition to the so-called thermostat.

If they're all thermally-protected, why are they burning out? Are those built-in temperature switches not really designed to protect the windings, but rather, just to pull the plug before there's a serious fire?

We even wondered if the drives are generating line harmonics that might be causing some stress to the single-phase fans. May need to rent or borrow a power quality analyzer - not the sort of thing we can justify purchasing.

Before you ask why we haven't done extensive tests and made measurements ourselves, that's coming. We're into harvest season here again and pretty soon that farm yard is going to be a hurricane of grain trucks and augers and fans going 24 / 7. We just got finished wiring up 6 bins with fans, augers and a couple of drags associated with a giant grain dryer installation that was fired up for the first time last year in the middle of a blizzard.


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## Forge Boyz (Nov 7, 2014)

Check out galco. I haven't used any of these but they look very similar to ones I've seen on generators. https://www.galco.com/shop/Analog-Panel-Meters-Panel-Meters-and-Gauges
I just used a trumeter digital/analoge look ammeter that I got from automationdirect.com. That one is mounted inside though.

Sent from my SM-G970U using Tapatalk


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## gpop (May 14, 2018)

Common problems on fans is the mechanic breaks the pulley then installs the wrong one or fails to remember to adjust a variable sized pulley.

The motor thermals should work as designed and are measuring winding temp so that should avoid burning a winding. Its does nothing to protect against other problems like moisture and bearing failure. 

Are the motors rated for this use and are they mounted correctly in correlation to the weep hole (side mounting or upside down will cause a problem if you dont move the weep hole). 

How often are they lubricated (A mechanic with a grease guy can kill a motor in no time) 

Any weather conditions like lightning or brown outs.

You can install voltage protection relays that will shut the motors down if there is a voltage drop. Get one with a reset timer if there are lots of brown outs.

A few guys on here are field engineers if you have a burnt out motor disassemble it and take pictures of the windings/bearings and the location where the motor failed so they can help you.


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## micromind (Aug 11, 2007)

On a farm, look at how the motor is greased and more important, what type of grease they are using. 

Using normal grease in a motor bearing will result in a sticky gummed-up mess that doesn't lubricate anything. 

Also, farmers are notorious for pumping about 50 strokes of grease into just about everything.....this will also cause the motor to fail fairly quickly.


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## PVGuy (Apr 22, 2017)

gpop said:


> Common problems on fans is the mechanic breaks the pulley then installs the wrong one or fails to remember to adjust a variable sized pulley.
> 
> The motor thermals should work as designed and are measuring winding temp so that should avoid burning a winding. Its does nothing to protect against other problems like moisture and bearing failure.
> 
> ...


 The last time we went to check out a fried motor we found it guarded by wasps, but one could be had. I am aware of the low-voltage protection option but as I said, I will be surprised if that's the issue given the motor ratings. I could also be proven wrong. We've never had a chance to do some proper testing when the place is really rolling. It's semi-pointless to start up fans on empty bins so you have to be available during peak usage and at that point we've usually got our hands full with other farmers too.

Dunno about lubrication; they would not seem to be well-designed for maintenance(?) Some of them are like this:
http://www.valleyagro.com/img/products/Brock_Fans.jpg
and some are like this:
https://www.flamanagriculture.com/assets/554/346/1bXG70xTpXVFwygBAFAO.png

and if those links don't work just search "grain bin aeration fans." That's all I did. In any event they're all direct drive.
I very much appreciate your thoughts. I'll see if I can get hold of a motor; I usually like to take apart failed stuff anyway.


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## PVGuy (Apr 22, 2017)

micromind said:


> On a farm, look at how the motor is greased and more important, what type of grease they are using.
> 
> Using normal grease in a motor bearing will result in a sticky gummed-up mess that doesn't lubricate anything.
> 
> Also, farmers are notorious for pumping about 50 strokes of grease into just about everything.....this will also cause the motor to fail fairly quickly.


 I really have no idea if they lubricate them at all. I'll certainly find out. It's quite a lot of work to get at them. (The motors that is.) Now I'm really curious; it seems like such an obvious thing to ask in retrospect. I'll be on site tomorrow and I may have a chance to follow up; we'll be working on some other stuff. ...
And the phone literally just rang, and the plan has changed. <sigh>

Thanks for the response.


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## gpop (May 14, 2018)

There smaller than i was expecting.

To be honest im suspecting there may be cap failure, misdiagnosis and lack of inspection. 
As its a single phase with thermal protection its easy to misread a open thermal for a burnt up motor. 
If you go to the fan and attempt to start it and it fails then generally then next step is to open the disconnect and test. The trouble is the motor at this point (with a bad cap) has been heated to the point that the thermal is open. So it tests bad. 

If the motor is hot to the touch i would suspect a open thermal. (seized or bad cap) will require 30 minutes before it can be tested with a ohm meter. 
If the breaker is tripped and instantly trips on reset i would suspect a dead short
If the breaker hold for 20 seconds before tripping i would suspect the bad cap

Thermals reset when they cool down so if the fan is not inspected every few day once the cap fails it simply heats up thermally opens then resets and repeats until it burns up. Some motors have pop out breakers that will trip and stop this cycle.


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