Bareshaft horsepower

[Sparkyman]

Can someone please explain the term 'Bareshaft Horsepower' to me. Thanks

 

[aolalde]

The terminology I know is BHP, Brake Horsepower. It is the Horsepower made available for driving machinery other than itself, as it could be measured by a dynamometer.

 

[electricpete]

Also I have seen the term "shaft horsepower" used to describe the same thing as brake horsepower mentioned by aolalde.

I have never heared bareshaft horsepower. Sounds like two possibilities:
1 - They meant brake or shaft horsepower.
2 - Maybe they were trying to refer to electric power which must be supplied to keep a motor running at no load (bare shaft = no load?) ? In that case it is only a small amount a few percent of full load necessary to supply internal motor losses.

I would ask them for clarification.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[Sparkyman]

This is a reply I got from Artesi in the pump engineering forum

Bare-shaft horse power is, in the case of a pump unit - the power input to the pump shaft (which already includes the pump losses and ineficiencies),it does not include any losses for the coupling or the drive unit.

To put it another way: if the pump at the point of best efficieny requires 100kW and the loss through the coupling is 0.5kW and the inefficiencies of the electric motor driver are 3.5kW,then the energy input to operate the pump at BEP would be 104kW, calculated from voltage, amps,power factor, efficiency etc.
This becomes the input power to the pump unit as compared to the input power at the pump shaft, ie., 100/104 Kw .

If it was a engine driven unit, you would need to measure the fuel input and convert that to total energy input - this is not so easy to do but can be calculated by the engine manufacturer.
Naresuan University
Phitsanulok
Thailand

 

[jraef]

That is a new one on me. That iswhat Ithought was BHP, but sounds as though they break it down a little further.
So would it be abbreviated as BS-HP?

Got my new info for the day, thanks.
I'm taking the rest of the day off now.

 

[aolalde]

Sparkyman.

The second part of your post contradicts the first paragraph.

“Bare-shaft horse power is, in the case of a pump unit - the power input to the pump shaft (which already includes the pump losses and inefficiencies),it does not include any losses for the coupling or the drive unit.” -- THIS DEFINES EXACTLY BREAKE HORSEPOWER BHP.

I wonder, how did you messed with the motor if “it does not include any losses for the coupling or the driven unit”?