I was recently called in to determine why a machine wouldn't start up. The display indicated the oil reserve was low so the plant engineer had re-filled the reservoir but still no start-up. I took off the reservoir controls cover and manually blocked the low level switch so it wouldn't trip. Same problem. So I opened up the electrical box and found a common variable frequency motor controller. We started looking at the drive train and, sure enough, there it was. A set screw on one of the belt drive gears had loosened and the steel link belt it drove had drifted 1/16" to the side and caught on some hardware. The VFD was doing it's job and signaling an overload on startup (insteat of self-destructing the system like an old contactor-based control would have done). The display was reading "oL" which they took to mean "oil" when it meant the obvious ("OL"). Ten minutes later I was out of the plant and production was back to 100%.
Thanks, William. The fact that it's a "background" noise means it will be more obvious at night when other sounds masking it during the day have disappeared. This is especially true in the country, where most turbines are located. If it's also low-frequency, that magnifies the problem, since those travel through the ground and are much harder to block from entry into one's house (and bedroom) than high frequency sounds. Here's a report on nighttime sounds driving people nuts in many places. http://www.nbcnews.com/science/mysterious-hum-driving-people-crazy-around-world-6C10760872 Note the low percentage (2) of people noticing these sounds. I'd probably be one of them. Also note where the problem occurs most and why (rural and suburban vs urban). Also the age group, probably because older people are lighter sleepers. So yes, it's in the ear of the hearer. But that doesn't diminish the distress. I often wish I didn't hear this stuff.
Good points Ann. What is definite is that whatever the noise is, it is not a forground noise like a chainsaw or diesel engine, but something far more subtle, if it is there at all. Of course, there are also folks who get annoyed at the sound of the hard drive in my Dell notebook computer. So it seems that noise must be in the ear of the beholder, or something like that.
So you finally found wind turbines to listen to! Thanks for reporting back to us. 100 yards is a good distance. However, from recent experience with noisy neighbors, one of them 500 yards away and up a hill, and related research on sound proofing techniques I've learned a lot about how "sound travels". Actually, it's how "sounds travel," because different sounds travel in different ways through the air or the ground, which differs yet more depending on relative elevations between Point A and Point B, and objects in between. It's actually quite complex. My point is, people farther away than you were could easily be getting different sounds, especially those low-frequency ones that drive some of us nuts, and which others of us apparently can't hear. I find it interesting that the "musical person" noticed something. I'm also musical, and I wonder how much that simply means I notice sounds more, or notice differences in them more.
Thanks William, I think that's a compliment of sorts. Yes, I tend to be very analytical and think in terms of "problem solving" much, maybe most, of the time. Usually I don 't think of it as such, but more often as finding or fixing things. Like in shopping, looking online for tall sizes (not at all easy), or for an obscure book. Work-related is more like where's the latest info on new robotic designs, where are good photos for this news item, or how can I crowbar information out of PR people/sources for this press release (harder than you might think). Both of these types of seek-and-find missions require similar skills and processes. During all this, I often think "why is this so hard to find"? or "why is this system so hard to use?" or "it would work so much better if you put XYZ on this web page instead of the next web page" or the like. I nearly always see ways to make things work better. Of course, that doesn't mean that making those changes will be feasible.
Ann, it has been obvious to me that you are in the problem solving mode much of the time. That happens a lot to engineers, and sometimes it drives others to distraction, or worse. We look at something and usually see some way, which we would consider obvious, to make it better. Of course it is always easier to see how to improve a design than it is to create that design, and even easier when it is somebody else's design.
And trouble shooting is an extension of that, it seems to me. It almost becomes a "first nature" thing, always considering how things are working and how they should be working. Great for when one is asked to fix something, but not quite a s great when others don't want to hear about what needs to be fixed.
On a totally different subject, I finally had a chance to listen to a huge wind turbine in operation. Actually, I had the chance to listen for it, since I was not able to percieve any sound at all, from about a hundred yards, which is where the "Keep Out" sign was placed. None of my group heard anything, except for one musical person who thought that they might be hearing a slight sound as each blade passed the support structure. In short, it was no louder than a quiet library would be if all the rules were in full force.
I guess I've done more problem solving than I realized, William, since much of this seems obvious or elementary. Including as a part of my employment. It's been mostly at a very small level compared to what you do, but the principles are the same.
Ann, yes, it is quite obvious to both you and me, but as you say, it is hidden from alot of people. Of course I have the advantage of having done a whole lot ofproblem solving as a regular portion of my employment. That winds up being quite an advantage. Also, finding out what is wrong with a piece of equipment that one has designed ten years earlier still gives one a real advantage.
In general, getting enough information tounderstand how a system should be working, prior to starting to even lookat it, is a big benefit. Howwould one know that something was wrong unless one knew what it was like when it was right.
William, thanks for that very clear and thorough description of what it takes to solve problems like this one. It's a good map, actually, for non-engineering problem-solving, as well. There has to be an agreement about what's happening; i.e., that there is a problem. There has to be knowledge of the way something is supposed to work, and observation of how it actually is working, and analysis of why the difference. This seems like such an elementary map of how to proceed, so elementary, yet I find it escapes many people.
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