One horsepower is 746 watts. But that assumes a power factor of 1.0,
i.e., no inductive or capacitive component. Most motors are inductive
when running and some have a large capacitive load when starting.
A PF of 1.0 means you can multiply the voltage (120 vac) and current to
get watts. Light bulbs behave well this way.
First, go to google.com, and type in "converting electrical motor hp to
watts/amps" in the box in the middle of the page. This does a web
search. Click on the first result returned.
Then, go to http://groups.google.com/group/alt.home.repair , type in
"rebuilds battery packs for cordless tools" in the search box to the
right. This does a search of alt.home.repair, where you posted this
question. Click on the first result returned.
OK, wise ass, you type it in and see how many hits you get. None.
Ditto for "converting electrical hp to watts" , and a few other
variations, which I did before my post. If you can't help, keep your
comments to yourself!
It doesn't really work anyway. There are so many different types of
motors and lies they tell about the power that the only valid way to
determine the ampacity of the supply conductors is to use the
nameplate rating on the motor. If you look at the typical amps to HP
in the electric code table you will see they are nowhere near that
"watts/hp" theoretical range.
Bob - You must be doing something wrong. Do what he said, leave off
quotes and remove the '/' in watts/amps and you will get all the info
you are looking for!
A little bit of teaching a man to fish vs giving him his fish here. Not
that the regulars don't like fishing for other people. Don't get me
wrong, we like fish. Mmmm, fish.
Inviato da X-Privat.Org - Registrazione gratuita http://www.x-privat.org/join.php
Well, hold on. Go try those two searches. I didn't even type it in... I
just copy and pasted right from your question. The first hit in both
cases had a pretty good answer, including the company that hallerb
Bob, *even* if seaching didn't work, you're as bad as you think Kevin
is. If you wanted to not get the kind of reply Kevin gave, you could
have started your first post with "I searched google, but..."
You could have replied that way even now, without resorting to vulgar
insults. Do you think it is cool to use them?
And it's your mistake you didn't write down the name of the rebuilder
when it was first posted.
No. It's you who should be quiet. Everything is free here. If you
didn't like his answer, ignore it or say that you did look in google.
Then you'll seem like a grown-up instead of someone on steroids.
There is no one formula to convert the HP to watts/amps. YOu did not
mention if it was a 3 phase or single phase motor. Also some motors are
more efficiant than others. I work for a large industrial plant. We get in
some 3 phase motors that take 2 amps and some that take almost 4 amps to
produce the same ammount of work. When the motors are replaced we have to
look at the nameplate and see how much current they take so we can resize
the overloads or change the setup for the inverters that drive them.
A clamp-on ammeter will tell you pretty accurately and quickly. Keep in mind
that the current will increase some as the pressure builds toward cutoff and
there is a short time very high current draw at startup. Clamp-on ammeters
have gotten cheap enough that anyone doing electrical work should have one.
Watts is amperes times volts. Energy conversion
says that one HP is about 750 watts. However you
will never find a 1 hp motor that uses 750 watts
or 6.25 A at 120 V. For example my 1hp saw motor
is rated at 12 A, and a rough A measurement is
about 10.5 A when the motor is running free. I
also have a 1/3 hp motor that is rated at 6 A.
Your best bet is to look at some motor plates of
motors similar to what you need. Age, type of
motor, and size mean that a simple formula is
unlikely to be helpful.
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