![]() ![]() The tower is perhaps one of the most important parts of a wind turbine. It can also be well over half the cost of a system overall. ![]() Pearl River Tower integrates innovative technologies to significantly reduce the amount of energy required to operate the building, and to promote the highest levels. Guidelines suggest that a tower should be 3. Air is very fluid (like water) - any obstruction to the wind creates turbulance (like the wake behind a boat). Venger Wind and US renewable distributor SWG Energy just installed the world’s largest rooftop wind farm atop the Oklahoma Medical Research Foundation (OMRF) in. How to build an electricity producing wind turbine. This web site talks about the virtues and vices of various Ametek motors when used as generators. Wind Turbine – Materials and Manufacturing Fact Sheet August 29, 2001 Princeton Energy Resources International, LLC 2 competitive with other power sources, because. Installing a small wind electric system? Proper installation and maintenance are key to getting the most out of your system. You cant see it, or detect it - but it's hard on a wind turbine and it costs lots of power. Oftain times the best time/money spent on a system is on a nice tall tower. In practice, we cannot always follow guidelines, we have to work with available resources (time and money). In some places there are few obstructions on the ground, the ground is flat - and an effective tower might be easy. Where we're located (in the Rocky Mountains) we have fairly tall trees - lots of ridgetops. Scary climbing this sort of thing! There are a couple common approaches to building towers. Free standing towers require significant foundations, they have no guy wires. They are either lattice towers, or made from pipe/tubing. Their main advantage I think is their appearance, and the very small footprint required. Most very large (utility scale) wind turbines are on free standing towers, they don't seem very commonly used in smaller system probably because of their cost. Guyed lattice towers are common. Usually they are erected with a jin pole or a crane - the same equipment would also be required to install the wind turbine. We have very little experience with these towers. Both types mentioned above require climbing. From here on, we'll discuss simple towers made from pipe that can be tipped up with a winch, or a truck. Pictured above is a drawing of a simple 4. Of course many things could be changed, it could be scaled up or down - and there are other ways of doing things. It's typical of several that we've built though and is very workable for a 8 - 1. It's made from Sched 4. Pipe comes in 2. 1' sections, so the tower itself is made from two lengths of pipe. Pipe is measured by its inner diameter. The top section (2. Most wind turbines we build now use 1. The longer the jin pole, the easier it is to raise the tower. If its too short, the forces really add up, and it goes up and down too quickly. There also needs to be a heavy cable (3/8. This cable takes all the force when raising, or lowering the tower. This tower has 2 sets of guy wires. The side guy wires should be inline with the pivot as they must support the tower while its being raised and lowered. The top set of guy wires should be attached as near the top of the tower as possible such that the blades of the wind turbine cannot hit it. So for a 1. 0' machine, we'd have the top guy wires about 5' from the tower top. The top guy wires take almost all the force from the wind turbine, so they should be heavier than the bottom ones. I've used lighter stuff, but I wouldn't suggest anybody else try it. The second set of guy wires should be about where the two pipes join - about 2. They serve mostly to keep the tower rigid, they can be lighter stuff. Notice the pivot is made from a simple pipe over pipe arangement. Notice the window in the pipe where the power chord comes out. This allows the machine to pivot easily, and the length of the chord can wind up (or wind down) over time without being a problem. We have a locking plug here so that on occasion we can unplug the maching and allow the chord to unwind if need be. If the site is not turbulant - this is rarely required. With a new installation, it's probably wise to check this frequently to get an idea how oftain it needs attention. I check mine about every 3 months. The one pictured would be very strong - I've made much lighter duty ones that worked fine. It needs to support the weight of the tower - thats all. The foundation on which the tower/pivot sits is also not a big deal. Much more important are the guy wire anchors. A simple metal 'foot' that can be staked down will suffice for the tower, because all the force is straight down. Main thing is that it cannot slide easily, and that it doesn't sink into the ground. If it sinks it will cause the guy wires to loosen. So, a small concrete pad might be a nice tower foundation, but it's not required. Also in the picture above is a drawing of the same tower in the 'down' position. You can see how the side guy wires must go up and down with it. Its nice if the guy wires dont loosen - or tighten when the tower goes up and down. In a perfect world, if the ground is perfectly flat and the guy wire anchors are at exactly the same elevation and inline perfectly with the pivot, that would be the case. Otherwise though, it's better if the guy wires tighten as you raise it and loosen a bit when you lower it. That will happen when the guy wire anchors are slightly in front of the pivot (by in front, I mean on the same side of the pivot that the tower tips towards, and opposite from the side where you'd have the winch/truck). It will also happen if the guy wire anchors are at lower elevation than the pivot. Also shown in the bottom drawing are two 'guy wires' attached to the top of the gin pole. This prevents the jin pole from tipping over. We dont have this on all the towers we've put up, but it's nice insurance. They dont need to be real tight, I dont think turn buckles are required - and once the tower is raised, they can be removed so folks dont trip over them. They are nice to have in place while rasing and lowering though.. Again, like all things - we have to work with what we have. Up here its quite rocky, the ground is almost never level so we work around what we have. My tower has one guy wire much higher than the pivot, one is much lower. My pivot is fairly loose (it has slop to allow the tower to tip some to the side) and when going up or down, it's supported only be 1 of the side guy wires and it leans to the side. Not ideal - but workable. Its very important when raising a tower for the first time to go very slowly, pay close attention the guy wires. If both side guy wires seem to be tight - time to stop, lower the tower again, make adjustments. Once a guy wire gets tight you have no way of knowing how much force is on it, it's quite easy to break one, or tear it out of its anchor. Whenever raising a tower, it's important to double and triple check *everything* before you start. Its important to make sure everyone is out of the 'fall zone'. There could always be surprises and its best to prepare for the worst with these things. Pictured above is Wards tower - first time we ever raised it. We double checked everything, only to find out afterwards that we'd forgot to hook up guy wires on the west side. We also didn't test raise it first, we were confident enough that we put the machine on it. The only thing we did correctly here.. This is a nice way to anchor into solid rock. We drill a hole (usually 6. Not shown very well here, but - each guy wire is attached to a turn buckle, and inside the loop we have a 'thimble' - which keeps the turnbuckle from wearing into the steel cable. The guy wire is fastened with 3 cable clamps. Here's a tilt up tower in a rather rocky location. Here, we were able to mount all the guy wires, the pivot, and the winch into solid granit. This inexpensive worm gear winch works nicely for small towers. You can take off the handle and fit a 1/2. These imported winches cost $2. They work nicely, though it wouldn't hurt to have something a bit heavier for the tower described above in the drawings. The one in the picture above is welded to re- bar that's epoxied into the rock. Pictured above is a tower almost exactly like the one in the drawings. Notice at the end we've welded 'feet' onto it that hold the end of it off the ground. Also notice the pivot - a simple 'H' shape made from pipe that sits on the ground. We staked this one down - it worked fine. Here is another shot of the same tower that shows the 'foot' a bit better. It's very helpful to have this while working on the machine. Another option is to have a 'stand' on the ground that the tower lands on. Ideally, it should hold the tower up enough so that the blades of the wind turbine can never hit the ground. Here is a nice pivot on a concrete foundation. This is under a 4. Concrete makes for a nice guy wire anchor. Here George built a nice form, and cast a re- bar loop into it to hook his turn buckles onto. Another possibility for guy wire anchors is a 'dead man'. Take a log (or something large and heavy) - wrap a chain around it, and bury it. If it's large enough it'll be fine. At another very rocky site, we built the pivot for the tower between two rocks. It's supported on each side by several pieces of re- bar that are epoxied into the rock. Tim didn't have rocks handy for guy wires, and simply pounded 4' steaks made from 2. Lots of pounding, but they seem quite solid and his 1. This may not be such a good option if the soil was loose, or wet. Up here it's dry/rocky and the soil is dense/clay like just a few inches down and it works fine. Pictured above is a machine assembled on the end of its tower. Before we put the machine on, we need to put lots of grease on the tower stub. I also like to make a sort of 'bushing' that goes between the tower top, and the wind turbine so that the pipe stub does not wear into the top of the wind turbine. Here is the bushing assembly we make for the tower stub. Basicly its just a cap that slips into the tower a couple inches. We put that in the tower, then we put the bronze bushing (a thrust bearing, a steel washer, or plastic bushing is also fine) over that. Then we run the wire through all that and put the machine over the top. Thats how the same assembly shown above looks when its in the tower top. This is a good, simple/cheap solution. In the past I've put machines right over the pipe stub. They'd work fine usually for about 1 year, then the pipe would be wearing into the top of the wind turbine, sometimes all the way through - but always enough to make them stiff to yaw. This setup prevents that and should hold up for a very long time. So those are just some thoughts and experiences with towers.
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