How Efficient is a 200Kw Petrol Engine When Driving an Electric Generator?

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Discussion Overview

The discussion revolves around the efficiency of a 200Kw petrol engine when used to drive an electric generator, specifically focusing on the power output and losses incurred during the process. It also explores a comparison between the efficiency of electrical systems and hydraulic systems in similar applications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that while a 200Kw petrol engine could drive a generator, the output would not be 200Kw due to power losses.
  • It is noted that power loss occurs primarily due to friction in the engine and generator, as well as resistances in the cables.
  • One participant raises a follow-up question comparing the efficiency of an engine driving a generator to an engine driving a hydraulic pump, seeking to understand which system would experience more power loss.
  • Another participant proposes that, in general, electrical systems tend to be more efficient than hydraulic systems.

Areas of Agreement / Disagreement

Participants generally agree that power loss occurs when driving a generator with a petrol engine, but there is no consensus on the specific efficiencies of the two systems being compared (electrical vs. hydraulic).

Contextual Notes

The discussion does not provide specific numerical efficiencies or detailed calculations, and assumptions about the conditions under which the systems operate are not fully explored.

Who May Find This Useful

Individuals interested in the efficiency of engine-driven systems, particularly in applications involving generators and hydraulic pumps, may find this discussion relevant.

Longbow
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Generator output question...

Hi there,

If I were to drive an electric generator from, for example, a 200Kw petrol engine, would the output of the generator also be 200Kw, or would I loose some power along the way? And if so, why?

Many thanks.
 
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If your efficiencies are good you might get close, but you won't get all of it.
 


Longbow said:
Hi there,

If I were to drive an electric generator from, for example, a 200Kw petrol engine, would the output of the generator also be 200Kw, or would I loose some power along the way? And if so, why?

Many thanks.

You would lose power due mostly to the engine having to overcome friction in both the engine itself and in the generator.
 


You'd lose power from the frictions inherent in the engine and from resistances inherent in the cables.
 


Thank you all for your replies. I didn't think it could as simple as my theory suggested.

Leading on from my first question; if I were to have:

A. An engine driving a generator, as above, to power an electric motor.

and

B. An identical engine driving a hydraulic pump powering a hydraulic motor.

As a rule of thumb, which system would be more efficient in terms of power loss between engine and motor?

I suppose a parallel example would be diesel-electric and diesel-hydraulic trains.
 


In general, electrical systems are more efficient than hydraulic systems.
 

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