Fine tuning

Summer dryness is making itself felt here and today I've made the change I make every year at about this time, - changing the 42 pole stator to the reduced version which has only 18 poles*.  The effects of doing this were two:

1. the rpm of the turbine increased from 793 to 885; this makes the efficiency at which the pelton converts hydraulic power to shaft power rather better (my optimum pelton speed is about 1000 rpm)
2. the rotor, which had to be packed off maximally to keep the rpm up to 793 with the 42 pole stator, could now not be packed off at all; this makes magnetic flux linkage between stator windings and rotating magnets better and so improves the efficiency of the alternator.

The benefit of these two efficiency improvements are apparent in the record of the turbine's output to the grid.  The output can be seen to have been lifted from 206 to 227 W.

OK, so it's not a huge increase in output, - just half a kWh per day.  But I needed to do the change so that as flows decrease further, I have the Smart drive set up for the coming weeks as I go down through my nozzle sizes.  As you can see from the output record, it only took 30 mins to do.

*see here and here to read about the reduced core stator