Horse power of motor

I finally snagged a good motor cheap and would like to know what horsepower
it is.
Spec's. are 1745 rpm, 115 V., 60 Hz, 1.7 A., 62 W.
Any of you guys familiar with the above to help me with a conversion?
Thanks in advance,
Ace
Reply to
Ace
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I seem to recall that a 1 HP motor uses just a bit more than 6 amps. Maybe 6.2. That would make yours a 1/4 HP motor.
Gary
Reply to
grice
It's a fractional horsepower motor. The power is 62 watts @ 746 watts/HP The input is 115 x 1.7 = 195 watts It looks a bit low on efficiency but at this size, that's possible.
John
Reply to
John
I won't quibble with the arithmetic, but......
The efficiency of such small motors is probably no better than 50%, which would make the power output of same in the 1/20th to 1/30th HP range, I'd bet.
Wolfgang
David Bill> 746 Watts per hp so that would be 0.083hp or 1/12th hp.
Reply to
wfhabicher
Hi Ace
The name plate info tells you that this motor will slow to 1745 RPM when loaded to 1/12th of a HP. You already know that the name plate predicts the motor will be drawing 1.7 amps from a 115VAC, 60 Hz line.
Jerry
Reply to
Jerry Martes
Where does the "1/12th of a HP" number come from? Calculated from 62 watts? That's the only thing I can *GUESS*... From that, does it follow that 744 watts would be roughly 1 HP? (since 62 * 12 = 744)
I've always been under the impression (perhaps wrong? If so, please *
DO* correct me!) that a nameplate is read as (using the OP's nameplate data for the example) "When you feed it 1.7 amps of 115V @ 60 Hz, the unloaded shaft will spin at 1745 RPM, developing ??? HP"? (I would assume that "???" is equal to 744/Watts?)
Reply to
Don Bruder
Hi Don
You and I agree, the name plate's 62 W means the motor is rated to deliver 62 Watts, which is 62/746 HP, which is close to 1/12th HP.
I am pretty sure the motor is one that will spin at real close to 1,800 RPM when unloaded. The guys who wrote the specs for the nameplate figured the motor will slow to 1,745 RPM when loaded to 1/12th HP.
The nameplate rated power being drawn from the line, is about 195 watts when the motor is loaded to 1/12th HP. 195 Watts input and 62 watts out isnt unrealistic efficiency.
Jerry
Reply to
Jerry Martes
"Don Bruder" wrote
You _might_ be wrong. If I was reading "62 watts" on a motor spec, I would take it as the motor's capacity to DISSIPATE HEAT. That is a very different thing from the motor's rated horsepower.
A motor that draws 1.7 amps at 115V is pulling about 200 watts of electrical power out of the wall. That electrical power is going partly into mechanical work at the shaft, and partly into heat in the windings. If the motor was perfectly efficient (super-conducting windings, no heat generated) then the shaft would be delivering roughly 1/4 HP. If the motor is dissipating 62 of those ~200 watts as heat, then it's about 2/3 efficient, and is therefore delivering ~1/6 HP.
-- TP
Reply to
tonyp
Rating motor output in watts is common on Japanese sub-fractional horsepower motors. Oriental Motor, for example, makes cute little 3- phase motors and gearmotors as small as 6 watts.
Ned Simmons
Reply to
Ned Simmons
Metric motor nameplate details list: Power. This is in watts or kilowatts. This is the rated shaft power of the motor. 746 watts = 1 HP. This is used to caculate what mechanical load the motor will drive. Volts. This is the line voltage to which the mtor should be connected. If a 3 phase motor, it's the phase to phase voltage. For a single phase it's phase to neutral. Amps. The full load current of the motor, ie what current it will draw at it's full rated power. This is used to calculate the electrical supply required, cables, fuses, overloads, etc. Speed. This is the synchronous speed of the motor less an amount for slippage. The actual speed will vary depending on the load connected so is best used as a guide only. In this case it's a 4 pole motor with a synchronous speed of 1800 RPM on 60 Hz. 2 pole motors are 3600 RPM and 6 pole are 1200 RPM less slippage in both cases.
Hope this helps.
John
Reply to
John
DC motors used on RC airplanes and such are often rated in watts. I believe this is more common with the motors coming from Europe. I do know they are incredibly powerful little beasts 20-30000 rpm with a 9 inch prop fed from an 8-12 cell battery. Scary whirling knives.
Reply to
daniel peterman
Actually it won't be 200 (or 187) watts of input power. The rating plate does not give the power factor of the motor but it's reasonable to assume .7 for a small four pole induction motor. That would give 131 watts of input power. That pushes the motor up to 50% efficiency. Still poor but a small single phase motor will not be good unless it is very well designed and optimised for the actual load.
Mark Rand RTFM
Reply to
Mark Rand
I have a GE motor that runs my filing machine. The nameplate says that it's a 1/12 HP 1725 RPM motor. It draws 2.1 amps @ 115 volts 60 cycles. 2.1 x 115 volts = 241.5 watts consumed while the output is 62.1222 watts. That's a pretty poor 25% effiency. ERS
Reply to
Eric R Snow
Something doesn't compute. 115 V x 1.7 A = 196 Watts - not 62 W.
Maybe they mean it draws 62 W running with no load.
Theoretically, 746 W = 1 HP. Figure 50 to 75% efficiency in a modest size motor. That's 0.26 HP at 100% efficiency, probably around 1/8 HP in the real world.
-- W§ mostly in m.s -
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Reply to
Winston Smith
With a motor load 115V x 1.7A = 196 volt amps NOT 196 Watts. The true dissipated power in Watts is Volt Amps x Power Factor. The motor is a lossy inductive load which draws both dissipative power and wattless reactive power from the supply. In this size motor the Power Factor can be as low as 0.5.
62 W is the motor mechanical output in mechanical watts - 746W = 1 HP. Stating the motor mechnical power output in Watts is standard European practice and I would expect it also to be pretty common in the USA.
Jim
Reply to
pentagrid

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