This shows why there is so much confusion about this issue, electric motors are mostly sold for engineering applications, engineers and designers want to know how much work the motor can usefully do. So most motors are rated for their 'duty' the rate of work the manufacturer decides will give leave the motor an acceptable life. Increasing the power to the motor will increase it's output but will cause it to overheat and shorten its life (in some cases dramatically). ICEs are usually sold embedded in a product, in this case the manufacturer has an incentive to exaggerate the power of the engine as the product is normally sold in a competitive market. The HP quoted for virtually all engines bears little relationship to the amount of useful work it can do (unless you are reusing the heat output for an application).
Cheers,
Perry
--- In electricboats@yahoogroups.com, "sirdarnell" <sirdarnell@...> wrote:
>
> Do you own any electric power tools with a motor rated in horsepower, like a drill press or table saw? If so, read the amps draw on the electrical label, they occasionally show watts. Go to a warehouse with an electric forklift, if the motor is rated in horsepower, check the electrical label. Go to a farm supply house look at conveyors or replacement motors for same, read the electrical label.
>
> Examples of motors from 3 companies:
> Dayton model # 4Z378 permanent magnet DC motor rated at 1 HP draws 5.3 amps at 180 Volts DC (984 watts.)
>
> Leeson 3HP mfr part# 120728.00 230volt AC saw motor draws 13 amps.
>
> Marathon Electric part # 5KC49PN0253 1 horsepower 115/230 volts AC draws 13.6/6.8 amps. More watts than the 3 HP motor from Leeson, but rated as 1 horsepower.
>
> --- In electricboats@yahoogroups.com, PERRY MONDESIR <perry.mondesir@> wrote:
> >
> > Hi Sir Darnell,   I'm sure that there are people on this forum who can explain this better than me but here goes anyway! The power rating of an engine (or motor) is the amount of energy it disapates over time, this includes work and heat. Engines (or motors) that have a high work to heat ratio are more efficient. A motor dissipating 749 watts is rated as one horsepower no matter what. Your nail in a coil is a one horse power engine, its just very inefficient. This is why electric motors with smaller ratings can replace higher rated ICEs. A 10hp ICE is likely to throw away 6HP as heat leaving 4HP as work. This is the same as a 5HP electric motor that throws away 1HP as heat.Hope this helpsPerry
>
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