"John H" wrote in message
...
On Thu, 03 Feb 2011 19:54:32 -0500, Wayne.B

wrote:

On Thu, 03 Feb 2011 13:42:52 -0500, John H
wrote:

I'm looking at electrical chain saws, a Poulan and a Husqvarna.

Brand Poulan Husqvarna
Item Number 118147 328965
Bar Length (Inches) 16.0 14.0
Amps (Amps) 13.5 13.5 Horsepower (HP)
3.5 9.7

They are both 13.5 Amp saws, but the Husqvarna gets almost three times
the
horsepower of the Poulan. How is this possible?

Also, the Poulan costs about $75, the Husqvarna about $270.

Manufacturers of electric tools play a lot of games with horsepower.
It's really very simple however.

watts = volts x amps = 120 x 15 = 1800 watts from a typical 15 amp
circuit

1000 watts = 1 kw = 1.34 horsepower at perfect (100%) efficiency.

Therefore the absolute maximum horsepower you can get on a 15 amp
circuit is 1.8 x 1.34 = 2.41

In reality you'd be lucky to get 2 hp at normal efficiencies.

Gearing has nothing to do with it, hp stays the same, RPM and torque
change.

Thanks. Thought there must be something fishy going on.


My pocket reference says a typical 1HP motor will draw 13 to 16 A at full
load. This falls right in line with what Wayne presented.

Here's a calculator to play with
http://www.onlineconversion.com/motor_horsepower.htm


--
Ziggy®