Installation manual

This is best illustrated in the Smart Drive test graph (Figure 1). A 10% reduction in the rotor

magnetism to the stator reduces the power line’s height by 10% and the amps / volts lines by

5% approximately.

Figure 1. Simplified Smart Drive test graph

This example assumes that calculations for your site data predicted that you could get 530

W at 1000 rpm (brown line) and 70% generator efficiency (red line) on a fully charged 48 V

DC bank at 56 V DC.

At maximum power, increasing or decreasing the rpm of the Smart Drive by packing will

make little difference to the output power it can produce, as the gradient of the brown line is

shallow.

In summer when a smaller jet is used and generation potential falls to only 200 W, the

turbine operates at close to the static pressure of the pipe line and the power curve has a

steep gradient. The speed of the turbine will be slow due to an oversized generator

combined with poor Pelton runner efficiency (because it is not running at the optimum

speed). Packing the magnetic rotor out a small amount will have a dramatic effect. This rotor

packing flattens and moves to the right of the brown power line and the red efficiency line;

this allows the Pelton rotor to pick up speed and become more efficient at extracting power

from the water jet, increasing the rpm even more.

Your PowerSpout will have been shipped with a Smart Drive generator optimised for

maximum efficiency at your maximum power level expected. This has the result of reducing

the requirement to pack the rotor. However, if you are using your PowerSpout PLT over a

wide range of flow rates some rotor packing will be needed. To improve efficiency at low flow

rates you should purchase a reduced core stator specially made to suit low flow conditions.

As low flow often coincides with very sunny weather, solar PV can normally make up any

shortfall in hydro power during dry periods.