How Does Baldor Rate Horsepower Nowadays?

[exmaxima1]

Saw a 1 hp Baldor grinder today and am puzzled by the rating. Nameplate reads 5.4 amps @ 115 volts. My cheap calculator says 115 x 5.4 = 621 watts. That seems shy of the 746 watt/hp value I was taught when I went to school. In fact my older Baldor 1/3 hp grinder (labeled as Rockwell) is rated at 3.4 amps @ 115 volts. My older yet Baldor 7307D even draws more than the newer "1 HP" versions at 5.8 amps. Any guesses?

 

[beakie]

does efficiency come into play?
don't see FLA (full load amps)

 

[larry_g]

does efficiency come into play?
don't see FLA (full load amps)

Sure it does, that figures to run at 120% eff.

lg
no neat sig line

 

[djb2]

Plug it into a Kill-a-watt or similar meter to see the real use.

If it's drawing less than 750 watts, it's not producing 1HP. It probably takes a full 1KW of electric power to produce 1HP of mechanical power (along with 255 watts of heat).

It's pretty common to lie about HP ratings on consumer products, despite Horsepower being a clearly defined unit. I do wonder why the FTC or NIST doesn't try to protect consumers.

 

[exmaxima1]

does efficiency come into play?
don't see FLA (full load amps)

It's been my understanding that the "Amps" rating on a grinder is the same as FLA. On a bare motor they list it as FLA as they don't know the application. It's listed so you can gauge your power circuit to handle it, so if it really is something like 120% more it would be mis-leading to the consumer and could pop a breaker. This just wreaks of a marketing ploy...

 

[jallyn]

Motors are more efficient than they used to be but as others have pointed out over 100% efficient is impossible. So rounding must be to blame. The motor must be about 0.6 HP and Baldor is rounding up to 1. This is misleading to be sure.

Larger motors are more efficient than smaller motors. For argument's sake a 100 HP motor is about 90% efficient and a 1 HP motor is about 80% efficient.

HP rating is the mechanical output of an electric motor. Kilowatt (kW) rating is the electrical input. The difference between the two is the efficiency at which the motor converts electrical energy into mechanical energy. So for a single-phase AC motor...

HP = (Volts X Amps X Power_Factor X Efficiency) / 746

Amps is the Full Load Amps (FLA). This is the current that the motor can safely continuously run without overheating the windings and damaging the insulation. Many times a Service Factor (SF) is given like 1.15 meaning it can run 15% over nameplate amps without damaging the windings. Since no SF is given the grinder is stuck with a motor that is only good for about 0.6 HP.

 

[exmaxima1]

Motors are more efficient than they used to be but as others have pointed out over 100% efficient is impossible. So rounding must be to blame. The motor must be about 0.6 HP and Baldor is rounding up to 1. This is misleading to be sure.
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Can you slow it down? Or does it give you all the power you want?

Yes, I agree with all your math. I guess my issue is with how they are NOW rating them. My older 1/2hp Baldor is fairly easy to bog down if I lay into it, so unless there is something "new" in the way Baldor rates power on their nameplates I would suspect that there would be no gain in buying a current 1hp model. It's probably the same guts with a new nameplate on it.

I guess I'm just getting old, but I much prefer having a circa 40's or 50's model "1/2hp" grinder that won't stop for anything vs a newer version that claims much more power but won't deliver on it....

 

[jallyn]

Yes, I agree with all your math. I guess my issue is with how they are NOW rating them. My older 1/2hp Baldor is fairly easy to bog down if I lay into it, so unless there is something "new" in the way Baldor rates power on their nameplates I would suspect that there would be no gain in buying a current 1hp model. It's probably the same guts with a new nameplate on it.

I guess I'm just getting old, but I much prefer having a circa 40's or 50's model "1/2hp" grinder that won't stop for anything vs a newer version that claims much more power but won't deliver on it....

Yeah. Older motors were built like tanks. A 1/2 HP of that era was certainly good to 1.0+ HP. Manufacturers are cutting cost like there is a prize for the most chintzy design. I worked with old DC crane motors that could be reverse plugged all day (change direction of the crane from full speed one direction to full speed the other direction). These were TENV (totally enclosed non-ventilated) motors living in 130 degrees Non-Ventilated! foundry bays full of smoke and dust and who knows if the bearings were getting greased...

 

[Davefr]

If you can't beat em join em. It looks like Baldor is lying about HP ratings just like Sears, HF and everybody else.

Too bad HP has become a basterdized criteria for evaluating motor power and many of then no longer provide an amp rating.

 

[MikeF2316]

If you can't beat em join em. It looks like Baldor is lying about HP ratings just like Sears, HF and everybody else.

Too bad HP has become a basterdized criteria for evaluating motor power and many of then no longer provide an amp rating.

Yup, once the 5 HP shop vacs hit the shelves, HP has become a meaningless unit for small electric motors. It would be nice if HP measured mechanical output (which is of course what does your work) and electrical on the nameplate was there to size the service. Like it used to be.