On a normal day at Harlaw Hydro there is little excitement, water comes down, the turbine goes round, and we generate green electricity. In the background there is routine remote monitoring of water levels to try and maximise what we generate and a monthly greasing of bearings.
Last week was different. Despite having plenty of water we were generating in the low 60Kws rather than the 70kws and there was more noise than normal. With cameras to see and remote access to the controls actual visits to the turbine house are limited but Monday was the day scheduled for greasing and the system was not just noisy it was vibrating. Something was clearly not right. The power generated was reduced until the vibration stopped and our maintenance engineers were contacted.
We have a 20mm grill in the water tower to stop debris (and fish) coming down the pipe,
• could this be partially blocked?
• But where did the vibration come from?
• And why was there a Heron standing beside our plunge pool?
Our engineers systematically checked the turbine, including removing the two inspection covers to allow them to inspect the runner (the part of the turbine that spins round and gives us the power). The runner was fine, as good as new, but what was that in the corner? A glove was put on and the body of a 5lb trout was fished out. The fish had been trapped round one of the guide vanes restricting and destabilising the flow to the runner, some how a small stick had also joined in. Fish removed, covers replaced and all now running perfectly.
The heron was disappointed.
Thanks to conscientious monitoring by our team and prompt action by Proterra (the firm that does our maintenance) all is well and no damage done. The addition of a microphone so that we can hear as well as see remotely is being considered.