Replies

1. 
   PaulBinCT | Feb 10, 2006 05:28pm | #1

   Very rough approximation is 746 watts = 1 hp.  Your (again rough) wattage is volts x amps.  Hopefully your amperage rating is accurate, and not a peak rating, as is often the case. But for a very very rough estimate: (110v times "X" amps) divided by 746 equals HP.

   Hope this is accurate enough for what you're doing.  Maybe trying to put a speed controller on this old router?

    

   PaulB

1. 
   maddog3 | Feb 10, 2006 06:03pm | #3

   oh don't be so modest....1Hp is = 746W

1. 
   BillHartmann | Feb 10, 2006 06:13pm | #4

   The trouble is that is only for POWER INTO THE MOTOR.That does not represent mechanical power out of the motor.You have inefficiencies in the motor. I need to do some research, but my guess is that 1-3 hp induction motors 80% would be fair estimate. And for universal motors maybe 70%.The other is that few people have a way of measuring POWER (WATTS).All they can come up with is VA which includes both watts and VARS (volt-amps reactive).After taking that into account my guess would be for "cheap" imported induction motors that 70% of VA's become usable mechancial HP upt to maybe 80% for high efficient US motors.

1. 
   PaulBinCT | Feb 10, 2006 06:22pm | #5

   Yeah..like Bill says Mad... ;)

   I just didn't want to go into the whole songanadance, I'm taking a WAG that the poster is trying to hook up a speed control, and figgered we'd give him a educated guess as to whether he had enough capacity.

   PaulB

1. 
   maddog3 | Feb 10, 2006 06:55pm | #7

   wadda kidder.......(0;

2. 
   maddog3 | Feb 10, 2006 06:53pm | #6

   as Clouseau would say, I'kneuw that" ....but the formulas above (without ...X eff.) are good enough for the ballpark or a simple calculation......I agree with you, in fact,
   I have taken old motors out of service,simply because some maint.muckymuck wanted to "save" energy.. by throwing out an old motor built from Iron and Steel and replace it with a nice shiny Aluminum one with more HP and less A on the dataplate...firmly entrenched in the idea that they saved some $$$.sometimes they did, and sometimes they didn't ....the older motors were very underated for HP but, the steel and iron frames and rotors could absorb much more current and they would keep on running longer ........than most of the newer types that replaced them.
   .. the rule of thumb.?
   ..if the breaker / fuses blew , replace the motor..
   ..if the overloads tripped, change the gearbox.occasionaly, a new motor would fail rather quickly, and the "old" one would be re-installed , much to the delight of some of the older plant mechanicsalso, advances in synthetic magnet wire insulation, CAD rotors , and aluminum alloys allowed motor builders, .....who have always played fast and loose with their ratings.....to rate them even larger.....Who is John Galt?

1. 
   JohnSprung | Feb 11, 2006 02:23am | #8

   >

   .....Who is John Galt?

   He's a video camera engineer, formerly of Sony, now at Panavision.   

    

   -- J.S.

    

2. 
   maddog3 | Feb 11, 2006 07:05am | #11

   you're kidding......I thought he was a fiction

3. 
   JohnSprung | Feb 13, 2006 09:51pm | #13

   I found him in a picture.  Good guy, I'll probably see him at HPA the week of the 20th. 

   http://www.dga.org/news/v26_5/feat_digitalodyssey.php3 

   A google search turns up other John Galt's, a 19th century novelist, a fictional character, a business consultant....   

    

   -- J.S.

    

4. 
   maddog3 | Feb 13, 2006 11:36pm | #14

   talk of motors made me think of the Galt character in "Atlas Shrugged " I recall seeing the name being used by a production company....but had no idea there was an actual person.....

2. 
   CCI | Feb 10, 2006 05:32pm | #2

   If I remember correctly you multiply volts x amps to give you the watts and divide that by 1000 to give kilowatts (KW).  1KW is equal to about 1.34HP.

3. 
   IdahoDon | Feb 11, 2006 06:12am | #9

   It seems like a joke, with all the manufacturers coming up with hp numbers that don't corrolate whatsoever with amps.  Compressors and shop vacs seem to be the worst.  PC upgraded the hp on the 690 router, except that it is the same amp rating and probably the same motor, just a different way to calculate hp and marketing.

    

   Beer was created so carpenters wouldn't rule the world.

1. 
   Catskinner | Feb 11, 2006 06:26am | #10

   It is a joke. On us.JLC and Tools Of The Trade have been after the industry for years to provide more realistic HP ratings. But the marketeers figure unless everyone in the industry agrees to this, then the honest guys are working at a disadvantage. Nobody wants to be first.Those absurd and arithmatically impossible numbers you see (like the Emerson Electric tools from a few years ago) boasting 6 Peak HP is pure cr#p but technically defensible in some extended sense. The motors are hooked up to a dyno (Magtrol I think) and run to rotor lock. The amperage draw right before the motor goes up in smoke is used to calculate peak developed horsepower.As someone pointed out earlier, in a perfect world 2 HP would be remarkable. Claims for any more than that at 110 VAC are pure cr#p.Success is not the key to happiness. Happiness is the key to success.
   -Albert Schweitzer, philosopher, physician, musician, Nobel laureate
   (1875-1965)

1. 
   JohnSprung | Feb 13, 2006 09:45pm | #12

   Baldor has up to 3 HP available for 115 Volt single phase.  Beyond 10 Hp, it's almost all three phase, except for one oddball farm fan motor.   

   http://www.baldor.com/products/specs.asp?1=1&catalog=L3706&product=AC+Motors&family=General+Purpose%7Cvw%5FACMotors%5FGeneralPurpose&winding=37WG0452&rating=40C+AMB%2DCONT 

    

   -- J.S.

    

4. 
   csnow | Feb 13, 2006 11:44pm | #15

   All those numbers are meaningless marketing hype.