# Turbine rpm with generator load

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1. Jun 24, 2016

### dilipbhanu

Hi, I have developed a hydro turbine (reaction type) I am testing the turbine for 3 bar input pressure (30 meter head). The turbine diameter is 30 inches. Torque produced is 109 Nm with 600 RPM without the generator (no load). As per Torque and RPM, power available at shaft (without generator) is 10HP.

Question: How do I calculate final power / RPM when the generator is attached. Will the RPM reduce because of the weight of the generator. If yes, what will be the final RPM if a the generator weight is 15 KG

2. Jun 25, 2016

### Jobrag

Are you intending to generate AC or DC?

3. Jun 25, 2016

### jack action

109 N.m (or 10 hp) is a load.
If the generator requires a 10 hp input @ 600 rpm, then your turbine will produce 10 hp @ 600 rpm.

If it requires less and your turbine is still producing 10 hp, the assembly will accelerate until the turbine's output equals the generator's input or when something will break.

If it requires more and your turbine is still producing 10 hp, the assembly will decelerate until the turbine's output equals the generator's input or when it completely stops.

4. Jun 26, 2016

### Rx7man

If it the turbine produces 10HP (7.5KW) without the generator, it's not going to change when you connect it, just turning the generator.. There'll be a little parasitic friction loss from bearings and perhaps the cooling fan when it's not under a load, and when it is generating power, there'll be some electrical inefficiency as well (~20% loss at full power, greater percentage at partial loads probably).

You need to find the torque/power curve of the turbine to determine where it makes the most power.

The weight of the generator alone will not change the power output, it will only change how fast it changes speed (a heavier one will take longer to get up to speed)