It now looked like it had to be a short circuit of some form that was putting a “load” on the turbine. The first place to look was the control cabinet, all the wires were sound and no short was evident. So the short had to be down wind so to speak. The turbine had to come down. Taking a 15m tower is not a quick process, but was surprisingly quick this time as the service engineer from Willow Energy inserted a single pulley to augment the winch which meant we needed a longer rope but half the muscle power.
Once the turbine was down and the covers off every thing looked in order. There was surprisingly little wear and tear evident. I will post pictures shortly.
When the turbine blades were pushed round there was clearly some resistance. It was very unlikely to be the bearings as there was no noise or vibration. The investigation therefore focused on short finding. First off the slip rings where checked, they were fine then course of action was to test the core. The three wire one for each phase that come from the core were insolated and the turbine manually turned. There was still resistance and it didn’t turn freely. Things started to look bad.
The next thing was to see it the short could be actually found on the core. We checked to see if the core was shorting with the turbine mounting but it wasn’t. From this it was concluded the short must be between phases in the core itself.
Luckily it was very windy that day gusting up to 30+ mph so once the turbine was reassembled it turned enough to at least power the inverter, so we know that is ok.
So sadly it looks like Windy Miller is right (see previous post http://www.renew-reuse-recycle.com/showarticle.pl?id=859;n=502) and the core has broken! Which means we have another wait till a new one can be delivered and fitted. Apparently core failure is not as un-common as one would have hoped.
I await Proven’s response, so far I have been impressed with them, and I hope and trust that a new core will be dispatched promptly and they will restart my warranty period again.
I will keep you posted.