The Turbine has commissioned and tested and was officially handed over yesterday. It’s currently producing about 2.4Kw as the river flow is low at the moment.
There are two ways of shutting the turbine down:-
1. An emergency stop.
2. A controlled (slow) shut down.
We tried a controlled shut down and the photo above is what happens at the vent pipe. The Turbine shuts off slowly but there is still a back up of water pressure in the pipe – enough to flood as shown. We haven’t yet dared to try an emergency stop. I guess that the pressure build up would be much greater – maybe a water spout???
Below is what happens at the forebay with the turbine shut down. When the Turbine is running there is no spillage at the forebay except for a small amount of water used to flush the leaves and other debris from the screener. The Turbine operation is controlled by a water level sensor in the forebay. If a drop in water level is detected the Turbine slows down to compensate. Hence the Turbine will always run at maximum capacity for the water flow available.
The good news is that, as predicted, with normal running the water level in the vent pipe is about 10cm below the water level in the forebay. The bad news is that any adjustment to the turbine causes fluctuations in the water level in the vent pipe. Currently we have installed an extra 60cm or so of pipe on the vent to prevent excessive flooding. I’m going to have to run the Turbine for a while to determine the optimum height for the vent pipe.