Ngine running at 900 RPM to power a generator

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Discussion Overview

The discussion revolves around the feasibility of using an engine running at 900 RPM to power a generator that operates at 1800 RPM, specifically addressing the implications for horsepower and torque when using a pulley system to achieve the necessary speed increase.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether half the available horsepower is lost when the RPM is doubled, suggesting that doubling the horsepower of the engine may be necessary.
  • Another participant argues that while the RPMs are doubled and torque is halved, the same amount of energy will be transferred, implying that the horsepower remains unchanged aside from losses due to pulley efficiency.
  • A third participant expresses gratitude for the previous input, indicating a desire for further validation of the claims made.
  • A later reply supports the second participant's view, reiterating that while the torque is halved due to the increased RPM, the motor torque remains the same, and provides a formula for torque in relation to power and RPM.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between horsepower, torque, and RPM in this context. There is no consensus on whether the horsepower needs to be doubled or if the existing horsepower is sufficient.

Contextual Notes

Participants reference the efficiency of the pulley system as a factor that may affect energy transfer, but do not provide specific details on its impact or efficiency ratings.

Josh111
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I am trying to use an engine running at 900 RPM to power a generator that needs to run at 1800 RPM ( This will go through a pulley)

My question is is half the available horsepower to the generator lost since the RPM's are doubled?
In other words, do I need to double the horsepower of the engine to do this?
 
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I don't think so. The RPM's are doubled, so the torque is halved, but I think the same amount of energy will be transferred, so you will have the same horsepower. Aside from the energy lost in the pulley (depending on its efficiency), I think the same engine will still work.
 


Thanks Airman.
 


I would still like someone to back me up on that. Does it sound right to the rest of you?
 


Airman,

Yes you are correct, the faster pulley will half the torque but the motor torque will remain the same.

Torque = Watts/ (2xpi x revs per sec) in Nm

the rest of your answer is correct also.
 

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