Horsepower Calculation

[Dobber1978]

Can someone confirm if this works to calculate horsepower for a motor?

I had some metering data provided on a 700hp motor. One of the measurements was kW and I was wondering if I can take this divide by 0.746 to get horsepower.

This would basically give the "electrical horsepower" then if I take machine efficieny into account this would give shaft mechanical horsepower.

i.e.
265kw measured
265/0.746 = 355.2hp what I called electrical horsepower above
355.2*.92 = 326.8hp shaft horsepower (assuming 92% efficient)

Thanks,

 

[itsmoked]

That's not bad. Unless you have the motor specs though, I believe big motors like that one are much more efficient than 92%. I'd guess more like 97%.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Dobber1978]

Thanks Keith,

I guessed at 92 as it is an older motor. If 92 is a poor assumption for this older machine I can bump it up a little. If 97 works for older machines I will use that. I won't be able to get name plate data in time so have to make an assumption.

Cheers,
Jeff

 

[itsmoked]

Got any more info about it, like approximate age, the look of it, voltage? There are guys here with much more experience than me who could probably give you a pretty accurate estimate with a little more data.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[melspuds]

If the stator and rotor width is about 18" and the motor is open frame with pedestal sleeve bearings and lower rpm. Most likely the motor is 97% maybe 98% efficient. The reason for the high efficiency as told to me stator windings are very tight into slots of the laminated steel creating stronger magnetic field. The same is true for the rotor windings.
Hope this helps,
Dave