Installation manual

8.4.8. Thermal Checks

A PowerSpout has an enclosed generator. The inside stator core temperature of the

generator will depend on:

 Output power of the turbine

 Revolutions (speed) of turbine – higher rpm has more cooling

 Ambient air temperature

 Water temperature

 Voltage of operation (lower voltages have more rectification losses)

The generator core is cooled by air flow across the stator. The warmed air then transfers this

heat through the aluminium bulkhead into the exhaust water of the hydro turbine. The air

temperature inside the housing is typically 30-40 degrees Celsius. This warm environment

ensures a near constant temperature of the Smart Drive bearings thus reducing moisture

ingress due to condensation that is common in the damp environments in which hydro

turbines are often installed.

Make sure the above thermal checks are done on the hottest day of the year. We have seen

some industrial applications where the air and water temperatures have exceeded 40°C,

resulting in the generator running too hot.

2 x side air vents and 1 x rear lid air vent – Keep them clean.

More cooling may be required in warmer climates. The ideal stator core temperature should

be in the range 40-60°C after 2-3 hours of operation.

EcoInnovation will have fitted 3 air vents; if your turbine is running too hot (hot climate, high

output and 12 V operation) then more cooling may be required. Contact EcoInnovation and

we will send out extra vents that you can easily install with a hole-saw.

The person responsible for installing and commissioning the turbine needs to do a thermal

check as outlined above and this needs to be repeated at the hottest time of the year.

At our test site in NZ, the temperature inside the bottom of a PowerSpout PLT (operating at

1.6kW on a 130m running head) reached 36°C. Due to a farm animal breaking the water

pipe, the unit was left not operating. The following data was inadvertently collected by a data

logger inside the turbine:

Case temperatures rose up to 39°C caused by sunlight heating. Ambient air temperatures

were around 25°C. Relative humidity was around 40% during operation and increased to

95% when not operating.

This observation is interesting and shows that a turbine should not be turned off for extended

periods of time. If your turbine is only used for winter generation, then the turbine should be

greased and removed to a dry indoor storage area with the back rear cover left off while in

storage.