Electrical Machines
Turbine Specific Speed
N_s = N\sqrt{P} / H^{5/4}
Variables
| Ns | Specific speed | - |
| N | Rotational speed | rpm |
| P | Turbine power output | kW |
| H | Net head | m |
Engineering Example
At N = 600 rpm, P = 1500 kW, H = 40 m: Ns = 600×√1500 / 40^1.25 ≈ 230, in the Francis turbine range.
Practical Site Example
The standard first check used to shortlist Pelton vs Francis vs Kaplan for a given site's head and flow.