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Three motors all rated at 2hp. One is 9A, one is 10A and when is 11.5A. The 9A says 230v the 11.5A is 240v. Is the one with more amps going to be more powerful even though they're all rated at to HP?

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Pat

http://toolsinaction.com/power-tool-inf ... and-volts/

The above link gives a really good answer to your question.

In short it says a tools amp rating is how much current it can take without overheating. So the higher amp tool is likely to last longer, but they all make the same power.

But if they both leave the station at the same time and are headed to Pasadena, which will arrive first?


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The fastest.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

There be Klownz here...

As a rule of thumb I've always used 7-8 amps per HP. 2-3 HP motors that run on 110 at 15 amps are a pipe dream.

They're probably a little different. The 2hp rating is most likely a conservative estimate. The actual point at which a motor will burn varies depending on how well it can dissipate heat.

Efficiency is probably different as well- even if the input power is equal, one may produce more power at the shaft because the other is wasting more as heat.

Also, RPM and torque are probably different (those two are inversely proportional). Depending on what you're using it for, you might want more of one or the other.

Dust collector

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Pat

Horsepower as a rating in itself is a pipe dream, IMHO. Basically, the formula is like this: volts times amps equals Watts. Watts times percent efficiency divided by 746 equals horsepower.

Here is the kicker: there are motor manufacturers that use the amp reading just before the overloads cut out, thus getting the highest amp reading possible to extrapolate into a HP rating. That doesn't account for the fact that the motor wasn't designed to work that hard, nor is it necessarily the most effective for the job.

Edited to say- your motors' current ratings are likely accurate. You didn't happen to mention any use of capacitors in the motor connection boxes, which would greatly increase the efficiency of your motor, by reducing inrush current and increasing power factor. Oh, dear. Nobody wanted to read a thesis.

Just use the one with start And a run capacitor, if there is one like that.

Oh come on, are you telling me the 5.5 hp shop vac with that little cord that plugs into the 110 outlet isn't really 5.5 hp?

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Jim Watts
http://jameswattsguitars.com

As Lincoln says, the 'peak horse power' rating is worthless. It just represents the motor output just before the lights go off. For air handling you will want continuous duty rated motor. Those motors will have a continuous duty HP rating. I would look for a fairly high efficiency rating also, probably something over 80%.

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Joe Beaver
Maker of Sawdust

Mymachinest friend also said that motors are further classified into industrial , commercial, farm duty , light duty contiinous operation etc.

I've never heard of an efficiency rating. Is that supposed to be on the spec plate?

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Pat

I've never heard of an efficiency rating. Is that supposed to be on the spec plate?

I don't think it is. The larger motor manufacturers like Baldor, usually list it on their web sites or catalogues.

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Joe Beaver
Maker of Sawdust