OVER LOAD WIRE

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Joethemechanic said:
I wonder how they came up with those numbers. Did they test a bunch of horses and then come up with an average? Were they fresh horses doing a one minute pull? Or is that what a horse can do all day long? Is there a capacity factor for horses? Are horses tested at a pressure of 29.92 and 59 degrees?
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“In trying to calculate the power of a single horse, Watt began by watching mill horses at work. Lashed to the spokes attached to the mill’s central machine drive shaft, the horses turned the shaft by walking in a 24-foot diameter circle, approximately 144 times in an hour. Watt estimated that each horse was pushing with a force of 180 pounds.


This led Watt to calculate that one horsepower was equivalent to one horse doing 33,000 foot-pounds of work in one minute. To reach this conclusion, Watt pictured a single horse raising a 33-pound bucket of water from the bottom of a 1000-foot-deep well in 60 seconds. That amount of work, Watt concluded, equaled one horsepower.”
 
230511-2405 EDT

An adult typical human male person can produce close to an average of 1 HP running up a 14 ft elevation change of stairs. High school physics experiment.

Average sustained power walking on a level surface is probably around 0.1 HP.

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Ok, so being that one kilocalorie = 3.96567 BTU, and dry oats have 1,700 kilocalories per pound, how efficient is a horse?
 
gar said:
230511-2405 EDT

An adult typical human male person can produce close to an average of 1 HP running up a 14 ft elevation change of stairs. High school physics experiment.

Average sustained power walking on a level surface is probably around 0.1 HP.

.
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25+ years ago I helped build a 4 quadrant DC drive system for a treadmill that was to be used to train Olympic athletes. They wanted a 2HP motor on it, I convinced them, after reading some studies saying that peak athletes could get up to 2-1/2HP in short bursts, that they should go with a 3HP motor. The long range runners did seem to average around 1HP peak, 1/2 HP sustained. But some of the sprinters pegged the meter at the 3HP limit of the motor… so I think those studies have not aged well against the modern athletes with more sophisticated training.

I refused to get on it and expose my lack of physical prowess…
“Sir, the goal is to make the motor GENERATE, not continuously motor!”
 
Let's say it is single phase 600 V rated copper conductor and longer than 2 feet.

NEC Art 310 Table 310.15(B)(16) I=20 A for Three Current-Carrying Conductors in Raceway, Cable, or Earth 30oC ambient- since if it is less than 100 A only 60oC is permissible [art.110.14].

Let's say it is in air and only two conductors [single core insulated 600 V] in free air one foot distance: Table 310.15(B)(17) 30 A [30oC ambient]

IEEE 835/94 page 34 :

0.6 to 5 kV Unshielded Single Conductor Extruded Dielectric Cable in Free Air - Single Isolated Cable 40ºC Air Ambient No Sun 2 Ft/s[wind]. =53 A

3.4.1 Adjust for changes in ambient temperature [30oC]:

I30oCamb=I40oCamb*√(75-30)/(75-40)=53*1.133=60 A
 
ptonsparky said:
Do you happen to know the standard horse he based his calculations on? Being a little facetious, but we watched some Draft horse pulls last year and those are not all created equal. Is that where the efficiency comes in to play?
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Sort of no different than going to truck and tractor pulls and they tell you some high figure the machine in front of you puts out, from machinery that was initially rated much lower. It can develop those high figures for short term, but will fail if you force it to do so for too long. Is also why on occasion they need towed from the competition track, they did over do it either too long or for enough times that something gave out.
 
Jraef said:
“In trying to calculate the power of a single horse, Watt began by watching mill horses at work. Lashed to the spokes attached to the mill’s central machine drive shaft, the horses turned the shaft by walking in a 24-foot diameter circle, approximately 144 times in an hour. Watt estimated that each horse was pushing with a force of 180 pounds.


This led Watt to calculate that one horsepower was equivalent to one horse doing 33,000 foot-pounds of work in one minute. To reach this conclusion, Watt pictured a single horse raising a 33-pound bucket of water from the bottom of a 1000-foot-deep well in 60 seconds. That amount of work, Watt concluded, equaled one horsepower.”
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Shouldn't that be 33,000/4
Or was it pound feet?
I get confused.
 
Joethemechanic said:
Probably a good thing they used horses and not cats
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ptonsparky said:
It could have been Ass Power.
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The real working animals that could work harder/longer were oxen. The movies and TV shows always showed horses, but the preferred animal to pull your wagon on the Oregon trail was oxen. After the 1849 gold rush oxen were short in supply and many turned to horses and mules, sort of like going from a full size pickup truck to a compact truck in many ways I suppose.
 
gar said:
230511-2405 EDT

An adult typical human male person can produce close to an average of 1 HP running up a 14 ft elevation change of stairs. High school physics experiment.

Average sustained power walking on a level surface is probably around 0.1 HP.

.
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I think that example is slightly misleading because you are just accounting for the effort the human makes to move their own body weight, vs carrying a weight at 550 ft lbs/sec.

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gar said:
230511-2405 EDT

An adult typical human male person can produce close to an average of 1 HP running up a 14 ft elevation change of stairs. High school physics experiment.

Average sustained power walking on a level surface is probably around 0.1 HP.

.
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But you are missing a time factor there. Big difference in power if you need 15 seconds vs 15 minutes to make that elevation change, same output work was done either way.
 
electrofelon said:
I think that example is slightly misleading because you are just accounting for the effort the human makes to move their own body weight, vs carrying a weight at 550 ft lbs/sec.

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That would be somewhat an analogy for efficiency. An electric motor would need a certain amount input power just to move the weight of it's own rotor and none that energy is transferred to the output shaft.
 
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