The Turbine has been off for a couple of weeks. Making a funny noise when turning slowly. I took it down today, thought all was well, then discovered that one of the threaded bars supporting the stator was completely broken in half. This is 10mm stainless steel!!!! So cut a new one, adjusted and hoisted the turbine. Also took the opportunity to change the old rusty galvanised shackles on the bottom of the guy wires with stainless ones.
I have AT LAST managed to find some Aluminium Blades from the USA. I am rather hoping they will last longer than the wooden ones which seem to break every two years. They are better balanced than the wooden ones. UPDATE - In use these blades are much more stable than the wooden ones. OK they are a little smaller and do not generate quite as much as the wooden ones, but they spin less violently in storms.
I took the turbine down, this was the first nice dry calm day since the storm. The damage to the stator can be repaired fortunately by cutting out the damaged fibreglass and recasting. Time for Carbon Fibre Blades I think......
Storm in the afternoon was strong enough to make the blades wizz round, despite being turned off with the Brake. The wind did abate in the evening so I took the plunge and turned the turbine on. Hugh Piggot tends to leave his running in high wind, because if the blades do turn with nothing to power, it can burn out the stator. The following morning a Blade had been blown off and another broken, with damage to the Stator visible.
Well the turbine had been working for a few days only when storm Doris appeared. I turned the turbine off, but noticed that it was not turning nice and slowly as it should. I thought that it might be rubbing the stator, so kept it turned off and took it down on February 24th only to find that half the stator had disintegrated. I have no idea why, there was no rubbing to be found when it was erected, and nothing had come loose. In the photo on the right you can see right through to the other side in the bottom left of the image. The damage is quite dramatic!! Ho Hum, make another one.
I decided to replace both discs, so had two new discs cut and galvanised. Bought a set of 24 magnets which were coated, unlike the original ones with a mild steel disc and magnets not galvanised. I also added a surround of stainless steel seizing wire to reinforce the unit. Here the unit is in the mould, ready for the fibreglass casting. I finally got the turbine up again on February 19th.
The cause of the loss of power was ALL the magnets coming off the inside disc, caused by the magnets rusting, and forcing the fibreglass mould off the metal disk, which then split and came off the turbine as potentially deadly missiles, sticking well into the ground nearby!! The disc itself seemed OK. The outside Disk appeared to be fine, and in fact was.
I noticed Turbine had suddenly lost power and increaed RPM at about 1145. Putting the BRAKE on the trubine did not stop it, so I left it on. It was too late in the day to take the turbine down, also it was quite windy. Taking the Turbine down the following day was dangerous, because it was windy and the blades were wizzing round, even at ground level. Below is the relevant graph of the Turbine Output showing sudden loss of power at about 0200hrs with little change in wind speed. However at about 1600 the RPM Dropped and output fell, but wind speed remained stable. On the right is a photo of one piece of the magnet mould.
The mast is repaired, a new Blade made and balanced, and a Gin Pole fitted. "Michael, are you winching?", "Yes" came the reply. We looked up, and all that was happening was the Gin Pole was bending under the compression force of the lift!! So a stronger pole was made, and fitted to the mast base frame rather than the mast itself to reduce pressure on the mast.
After a long run of very stormy weather, and some procrastination, the bent mast is repaired, the Blade replaced and ready to erect. The Hydrolic Ram System was struggling to lift the mast with the additional weight of the reinforced pipe. When it got to 45 Degrees, it broke in the middle at a weld point. Fortunately no-one was injured. The ladder broke the fall, and the heavy blade I had used to replace the broken one smashed on the ground, another blade was buried quite deep, but only split and the tail a little bent. No other apparent damage was found. Very Lucky!! So the mast went back for repair, I had to get some Dutch friends who were visiting the following week to bring wood for a new blade with them, because I could not source any Red Cedar in Cork. I decided to change the lifting method to a Tirfor Winch and Gin Pole which will put less strain on the mast when lifting. So another fitting into the rock for the winch, and more wire for the Gin Pole was fixed up. Here's hoping it works now!