On Fri, 03 Oct 2003 12:28:57 -0000, someone who calls themselves Chuck
wrote:

snip
The compressor currently has a 3/4 hp motor. At first glance I was kind of
depressed thinking "Gee, just about every compressor I see these days has 3
+ hp. Will this thing even work well?" In asking around I was told that
amperage plays a big part in the actual torque of the motor. This is where
I get confused... I thougth torque was the direct product of the motor's
hp. How does the amperage come into play? Can you have a "strong" or
"weak" 3/4 hp motor? What factors actually determine the torque? Or, am I
looking at this equation in the wrong way?

Your old motor is rated in actual usable HP, while almost all small
compressors (and many other consumer appliances where they sell by the
Gee Whiz Factor) now are marked with "Peak HP" - basically, the
highest horsepower output recorded right before the motor stalls.
(And goes up in flames if you don't pull the plug fast.) Just like
diagonal size inflation on TV screens...

Note that on all the motors of these new compressors they don't have
a motor manufacturer's HP rating on the sticker - Some I've seen leave
a blank space there (so they don't contradict the sales literature),
other motor nameplates have the HP block marked "Special". You have
to go by current draw and voltage to get the real motor ratings, and
by CFM @ PSI ratings to do a reasonable comparison between units.

I'm not going to do the math, but your 3/4 HP motor would probably
be sold as a "2 HP (Peak)" compressor today. 3 if they like to lie.

-- Bruce --
--
Bruce L. Bergman, POB 394, Woodland Hills CA 91365, USA
Electrician, Westend Electric (#726700) Agoura, CA

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