Locate the operating point

Compare the pump curve at each proposed speed with the system curve. Static head can remain even when flow approaches zero, unlike many friction losses. A low-speed curve that cannot reach that head does not establish positive delivery. Include tank levels and destination pressure, since the hydraulic requirement can change across the permitted operating range.

Separate no delivery from low input

A running motor's electrical input can remain positive even when delivered volume is negligible. Such an interval is not useful pumping simply because wind supplies the electricity. The selected pump may also have minimum-flow or time restrictions. KSB describes different operating regions; its explanation does not authorize continuous operation at an arbitrary low-flow point.

Check both initial and final tank levels in the permitted transfer. A speed acceptable near the start can become unable to provide the required head as source or receiving conditions change.

Request a useful-water envelope

Ask the pump designer to identify approved speed, flow, head and electrical input combinations, including source and destination level extremes. Then compare those combinations with available power and the delivery deadline. Another source may support a useful operating point when wind alone cannot. Give the accepted envelope to the wind integrator instead of a motor rating and a cubic scaling rule. The enquiry should distinguish hydraulic feasibility from electrical starting and control compatibility. No universal minimum speed, valve setting or direct turbine-to-pump connection is established by this general reasoning.