The Powerpal mill turbine is applicable to new or historic sites that have a limited operating head. Six models cover the maximum flow range from 0 to 80 to 0 to 1400 litres per second, larger flows can use multilple machines in tandem.
For high volume flow at low head, open channels and an immersed turbine are used with straight or elbow draft tubes.
For higher head, generally 3 to 6m, a volute casing and pipe fed, dry turbine is more favourable. The exact configuration also depends on site flood levels.
These turbines can have directly coupled Permanent Magnet generators that completely eliminate drive belts or gearboxes, this configuration is recommended for sites with high flow variance.
Where flow rates are more constant, induction generators with managed flow throughput are employed. In all cases grid export is the recomended duty.
A principle advantage with the mill series is virtually total noise elimination so energy production and residence can co-exist without interference. Powerpal Mill turbines are very heavilly constructed and integrated into heavy encasements, this with a constant torque runner, completely eliminates the low frequency generation of noise that other impulse type turbines, wheels or screws exhibit.