Question on electric motors...

[Twilight Fenrir]

Hello there,

So, the other day I had a guy tell me his air compressor was blown, and I helped him buy a new one. He gave me the electric motor off his old one, and now I'm somewhat flummoxed...

The motor is only about 4" in diameter, but it draws 15 amps! That should make it a bit over a 1.5 horse motor? I have a half horse motor on my drill press, and it's at least twice, if not 3 times the physical size....

So, what's the difference? o.o Could I really bolt this up to my drill press, and bore through anything? Is the difference in size because the newer motor isn't built for continuous operation, like the larger is? Or is it just a difference in technology over time? I always thought  motor was more or less a motor, that aside from making them brushless, and bigger and smaller, the technology hadn't really changed since their invention...

Any insight would be appreciated!

Richard

[Chillylulu]

Amps and hp numbers on plates and packages can be confusing. Think about all the hand tools with high hp and amp ratings. A Bosch 12 Amp 2.25 hp router motor is around 3" in diameter.

I'll let one of the electrical wizards here explain the reasons.  I do know that huge electrical motors have gotten smaller than some old ones.

Chilly

BTW -I don't think a router motor would do very well on a drill press.

[bonneyman]

15 amps is alot of current for a motor, especially for one that sounds so small size. Most power cords capacities are about that. Something smells fishy to me.

If I had access to a meg ohm meter, I'd do an insulation check on that motor before using it. Plus, a trip with it down to a local motor dealer you trust might shed some light on its specs.

JMHO

[Twilight Fenrir]

Yeah, I don't have access to an ampmeter like that... But there is just no way this little thing eats 15 amps... At least... I don't think? O.o hence the thread I guess! XD

[oldgoaly]

check the voltage! it does say 120v 60Hz)
it does say 15.0a

I can't see that motor running continuously at 15 amps

the BS about a motor develops 2.5 hp but it's only a 1/2hp nema rating is just BS! 
 

[rusty]

it draws 15 amps! That should make it a bit over a 1.5 horse motor? I have a half horse motor on my drill press, and it's at least twice, if not 3 times the physical size....

Name plate 15 amps or measured?

Could be very high power factor and not really making much horsepower.

Your drill press probably has a capacitor shaded motor, bigger, but more efficient and higher torque under load than a split shaded motor, also doesn't have brushes. brush motors go really really fast, but have lousy torque and draw lots of current without doing much. Thing vacuum cleaner motor, makes a lot of noise, mostly just pushes air around....

[oldtools]

Maybe "Fully Protected 15.0A" is the max (start-up) amps.? or fuse rating?
running amps maybe less... is it a Dyson?

[Aunt Phil]

That's a high efficiency electric motor given to us by a former high political official who repealed the Laws of Physics. 
Note the black paint.  It's black because black provides the best conversion of heat to short wave infrared for heat emissivity.

It will have a very limited life if loaded to capacity because it runs hotter than hell.

[Chillylulu]

That's a high efficiency electric motor given to us by a former high political official who repealed the Laws of Physics. 
Note the black paint.  It's black because black provides the best conversion of heat to short wave infrared for heat emissivity.

It will have a very limited life if loaded to capacity because it runs hotter than hell.

" repealed the Laws of Physics" Just gimme that ability (limitedable) for one day. That would fix up some stuff around hear. Especially messing with gravity, time, and space. Store some stuff in the future, when you think you might need it.

Chilly

[Twilight Fenrir]

Yeah, my drill press motor has a big capacitor on the side, just like all the other ones in my pile of motors :P Those old motors are brushless? Huh, I thought that was a fairly recent thing... But, I guess we're still discovering things we used to have...

The sticker on the side of the motor says it's a dyson, but it came out of a Campbell Hausfeld air compressor. I'm sure it has nothing to do with the vacuum company :P

Come to think of it, a Shop Vac supposedly has 6.5HP,but it just plugs into a regular outlet.... So what the heck are they measuring? XP

[Aunt Phil]

The current industry accepted system for determining horsepower of an electric motor is to place the motor on a dyno and crank the dyno up until the motor shoots flames or explodes. 
The highest current in the instant before the motor craps out is calculated to horsepower, and that is the figure used.

Like the sticker on the new car says, your mileage may vary.

Look at a 2014 Grainger book and compare motor offerings to those of 20 years ago.  The new motors are mostly crap regardless of manufacturer.

[oldgoaly]

Well about the time of the giant bag of wind was in office I was working for Uncle Sam in a refer shop (refrigeration) we were dropping fan coil motors left and right, they are a pain the replace! So tired of replacing replacement motors, I tore into a "newer motor" I found aluminum windings! with copper colored varnish!!! yep! those pieces of cr*p  were coming south of the boarder, copper wound ones were USA.  So spec' ing a particular motor saved thousands of motors, man hours, and they cost 2$ more.
Motors of a certain hp are not created equal!

[Chillylulu]

Well about the time of the giant bag of wind was in office I was working for Uncle Sam in a refer shop (refrigeration) we were dropping fan coil motors left and right, they are a pain the replace! So tired of replacing replacement motors, I tore into a "newer motor" I found aluminum windings! with copper colored varnish!!! yep! those pieces of cr*p  were coming south of the boarder, copper wound ones were USA.  So spec' ing a particular motor saved thousands of motors, man hours, and they cost 2$ more.
Motors of a certain hp are not created equal!

Personally, I can think of at least one improvement that has been due to freer trade with our southern neighbors.

Salsa overtook catsup as the #1 condiment in USA. Way to go salsa!

Chilly

[oldgoaly]

Nothing wrong with salsa! I put it on as much stuff as ketchup or is it catsup?
some bean counter and the ceo are to blame, not the people of another country.
I still don't see that motor running continuously for very long drawing 15 amp even 10 it is gonna generate a lot of heat!  could that be a garage door opener motor?
 

[rusty]

It is in the class of motors used for vacuums, sink disposals, sewing machines etc where operation is expected to be for a few minutes at a time, and total runtime for the life of the motor will be very low...

I would expect it to have bushings instead of bearings also...

Dyson, the vacuum folks also spun off an electric motor group....
google 'dyson digital motor'