1 hp is 1 hp. The 220v motor is more efficient.

Unless it is a 1HP 220VAC motor run at 110VAC

Since this can be a hair splitting argument, let me split a few hairs.

Presumably you mean that both motors are rated at 1hp of mechanical power at the shaft.

Now as Lynlynch pointed out, nominally a 220VAC motor will be more efficient than a 110VAC motor but this is not a requirement. One can find a 220VAC motor that is less efficient than a 110VAC motor. Regardless, the more efficient motor will draw less electric power to create the same mechanical power. But as we've hammered to death here, power cannot be saved. So neither motor has any power. The power comes from the grid.

I believe their horses are different.

Horse in traction at 220 Volt is more powerful. Possibly younger then the other.

Volts is directly proportional to current !

more excitation current is drawn when volts is more, keeping armature reactance same !! henceforth since the power generated is same !!!

i believe 110VAC motor is more efficient than 220VAC

This is a motor, so Voltage is almost (though not exactly) inversely proportional to current.

NO!

When power is constant, current is INVERSELY proportional to current. Generally, higher currents will have higher losses, so higher voltage motors (with lower current for the same power), will be more efficient.

It should be obvious that not all motors having the same voltage and current ratings produce the same power, so there are exceptions to the above...

the output of the motor with rate power (hp) is the same....

the manufacturer must doing the test before write the rate power in the name plate

but, the cable impedance in other voltage has difference influence to load.

this relate in the line losses.

the higher voltage can make higher efficiency in load usage.

in effective way.

I know, I know, it's supposed to be the same, but like Gibbs in the NCIS TV show says, "I feel it in my gut". Check the lock rotor amps on the two motors, or even on the same motor with dual voltage. Do the math, is there any difference?

I've always felt that 220 motors had more snap than 110s. The juice is coming in from both ends at the same time, gotta be better. And you can use smaller wires.

No flaming, please, I did say it was only a feeling.

Your argument is not complete.

1 HP is equal to 746 Watts

Watts = Volts times Amps (in simple terms)

If you get serious you also need to recognise that AC volts and AC amps do not max out at the same time, its called power factor, and real power is a little less than simple Volts times Amps

So you can see that you are both arguing about only one part of the equation - the volts part.

One respondent said that the higher voltage motor was more efficient. This may be the case because higher voltage means lower current for the same power and may mean lower resistance losses - but this is not necessarily so and the statement is not true.

Horsepower is roughly the amount of work a horse can do in a period to time. Volts is rather like how hard the horse pulls and amps is rather like how fast he pulls - and not surprisingly Force times Velocity is a valid power unit - its Newton Meters /sec in the metric system.

i think u need to complete ur explanation !! u were going good !

regards

If frankcorners wants more....then I guess I could have continued to say that

1 Newton meter/sec is a Watt

(for those who need it, Newton is a force unit and equals Kg by 9.8)

and as we already know, 746 Watts is 1 HP

so we've come full circle and shown how all the units are related.

By way of an add n - the related unit that confuses many is W hrs.

Watt Hours is an energy unit, that is, an amount of work and it equals Power by time

---is that enough frankcorners?

cheers

Your answer is not complete for an inductive load.

Watts = Volts x Amps x Power-factor

Opps sorry, I didnt finish reading you message complety sorry

They both have the same horse power. A 220 volt single phase one horse motor is the same power as a 110 volt one horse motor. Its like...one horse power...you win Tom.

A 220 volt system is normally a two phase system, though I know this was not specified in the question. A two phase, or even a three phase system (a system being the wires, transformers and generators as well as the motors) is more efficient than two or three separate systems because they can share iron, and reduce reluctance losses. (that is what makes a motor heat up) Copper losses (impedance losses) would be unchanged of course...though of course, copper wires must be twice as large for the lower voltage motors. This in itself might be a source of "inefficiency" in that the transformers and motors for the 110 system would have to be bigger, need larger shelves to sit upon, need larger and maybe more expensive bearings. But electrically, it makes no difference. I would be delighted to discover if there would be a savings in iron losses in a two phase motor because, of course, a motor is just a transformer with a rotating secondary. I suppose that fewer losses of "any" kind would mean greater horsepower out per watt in. But with motors, we are already running above 99% efficient...its hard to imagine much more savings than that! A tiny fraction of one percent may be too small a gnat to strain at. Not the 25 and 30 percent that I have heard people spouting about in the past.

You want real effiencies in copper savings, you have to go to high voltages, and maybe more important, higher frequencies. A 400 cycle transformer is a fraction the size of a 60 cycle transformer.

Watts is equal to volts times amps. wire size concerns itself only with amperage, and could not care less about the voltage applied to it. The insulation is not concerned about amperage (which should be zero...) but is very sensitive to voltage. I mention this point not because anybody doesn't know it, but rather to drive home that importance of the basics.

Expressed in electrical terms Power (watts) = voltage x current .

Applying this formula...

Horsepower Is an index of the amount of work a machine or motor can perform. One horsepower is equal to 746 watts. Since power is equal to torque multiplied by speed, horsepower is a measure of a motor's torque and speed capability; e.g., a 1 HP motor will produce 36 lb-in. at 1,750 rpm.
Formula:
HP = Torque (lb-in.) x Speed (RPM)/63,025
or
HP = Torque (lb-ft.) x Speed (RPM)/5,252
or
HP = Volts x Amps x Efficiency/746

Hope this helps.

When speaking to toms & jims (tom, I do not mean any offense to you) i believe we should be talking in the same language they do! I believe what they mean by power here is not power, but torque. What the common man refer to as power is really torque.

220V is normally 50 Hz and operate at lower speeds (close to 1500RPM) whereas 110V supply is 60Hz and operate at speeds close to 1800RPM

Since Power= Torque x speed x a Factor, when the speed is high torque will be low & vice versa. Hence a 1 hp operating on 220V 50Hz will be more powerful (high torque) compared with 1hp operating on 110V 60Hz.

220V is NEVER 50 Hz in N. America.

We in Asia have 1 phase 230-240V & 3 phase 400-415 systems.

the 3 phases are out of phase by 120 degrees. That is how when we measure Phase to neutral voltage we get 230V and when we measure phase to phase voltage we get Root 3 times 230 = 400V .

Frequency is always 50 Hz.

I know in the US frequency is 60Hz , but never could understand how the power supply is structured.

In fact about 20 years ago I did the mistake of ordering machines from the US with a 400V motor, which burnt out immediately when we connected to our power supply.

Can you tell us where we can get more information on how the US power supply is structured (not sure whether this is the correct English word!) ?

There's a good lad. If the wife is happy who cares if it's 110 or 220! Or, even 221. Whatever it takes!

Sorry, I haven't read through all the responses, but YES, the speed of light has changed! I think Al Gore had something to do with it.

But - seriously, 1 HP = 746 watts = ?Volts x ?Amps

If volts = 110, then amps = 6.78

If volts = 230. then amps = 3.24

'nuff said.

A 1 HP motor has the same power on 110volts or 220 volts.

VOLTS HELP US IN FIGURING OUT CURRENT REQUIRED FOR THAT MOTOR FOR EXAMPLE 1HP MOTOR = 746 WATTS AND

CURRENT REQUIRED FOR A 220 VOLTS SUPPLY IS 746/110 AMPS

SAME WAY 220 VOLT SUPPLY WILL REQUIRE 746/220 AMPS

VOLTAGE SUPPLIED HAS NOTHING TO DO WITH POWER.

IT ONLY HELPS IN CONDUCTOR SELECTION.

RAJ THAKRAL,P.E.

Please remember the power factor and efficiency of the motor, as electrical power = volts x amps x cos phi in single phase, and efficiency means you have to put in more than you get out and the 1hp or 746watts is the mechanical output power, 67% efficiency means 1hp out, 1.5 hp in!!

So, you select cable for the current it carries normally, not the power, amongst the other selection criteria e.g. voltage drop, temperature, grouping etc.

Obviously, for a small motor as used at 110V or 220V the power factor is low and the FLC will, therefore, be significantly higher than suggested in a few posts. (or please point me in the direction of pf1, eff 100% motors immediately!!!

I believe all the answers on efficiency and power factor have no direct dealing with the question . Let us assume these parameters are the same on this Motor.

Motor is rated for a particular HP. The currents in these 2 different voltages are different and so many other parameters will change.

The mechanica h.p will still be the same.

Raj Thakral

Heeeeeeeeeelp! Aaaaaaaargh!

tomkoko where are you?

We need your feed back.

I am curious to find out whether you are referring to power or torque

They are the same 1 hp is 1 hp. You can hook up a 220V motor to 110V just by moving a wire or two in the junction box. The 220V connection does not require a neutral, but does require a two pole breaker in the panel. The 110V connection require a bigger wire size than the 220V, but then only requires a single pole breaker in the panel. The line loss comes into play if you require any distance from the main source, this is based on amp draw, the 220 would be a better connection if using the same size wire. Something like a garden hose, the further away the less the flow at the end, use two hoses same flow as if close with a single. 220V is NOT a two phase connection, just the other side of a single phase.

220V is NOT a two phase connection, just the other side of a single phase.

You know it and I know it but by god man! The rest of the electrical 'experts' will argue with us until the end of time over it being something else!

This alone could easily push another 50+ posts in argument regardless of what facts, figures, and common logical reasoning gets presented.

Do you really want to go there?

220V is NOT a two phase connection, just the other side of a single phase. big lake.

Common terminology for typical residential single phase in the United States is 120/240 single phase.

A 240 volt circuit uses two fuses or breakers but still at best its occasionally referred to as a dual circuit feed or dual breaker line.

Any other derived value like 120/208 or 120/120/120 has to be three phase in origin. It can be just one or two lines coming from the three phase source but it would still be referred to as three phase because of the voltages present.

The reference of 'Source' is typically the nearest power transformer or similar voltage changing point that the loads common and ground lines are referenced to.

1 hp= 746 kw= volts x current cos & = volts x current

in definition power is same in both cases. but when you use 220 vac, is more potencial energy and the ampers are midtle, using 110 vac, you use twice ampers. Calorific energy Power= resist x current square. i thik that motor 220 vac is more efficent, using less amperes there are less hot

ejruiza,

Your post neatly includes most of the wrong assumptions that people have been making here. Please don't be offended that I chose your post to correct.

1. 1 hp= 746 kw= volts x current cos & = volts x current No, the real power equation is not W=V*I. You've taken the reduced power equation for DC current by ignoring your "cos &". The correct equation for Real Power is P=V*I*cosφ with φ being the angle between voltage and current. This is the power that is actually being converted from the electric voltage source by the motor to another form of energy (heat & the 1hp mechanical power)
2. Calorific energy Power= resist x current square. i thik that motor 220 vac is more efficent, using less amperes there are less hot This caloric energy will be the added heat produced by just the motor windings. It is tempting to think that by reducing the current less heating from wire losses will occur. But this is a false assumption for one will not necessarily have the same wire resistance with a 110vac motor and a 220vac motor if they are both rated as 1hp. Running the 220vac 1hp motor with 110vac, you would anticipate that only 0.5hp would be available at the motor shaft with the reduced voltage. (Assuming that the starter circuits do drop out for identical conditions.) So the 110vac 1hp motor will likely have less wire resistance than the 220vac 1hp motor, but not necessarily precisely half the resistance. So either motor running on the proper voltage may have higher parasitic winding power losses.

Lastly, since one must have different motors to provide identical mechanical power with different voltages, the voltage rating does not mandate which motor will have higher other parasitic losses like eddy currents in the magnetic cores or windage losses as the motor blows cooling air around itself, commutation power losses or even starter circuit configuration between the two motors. So either voltage motor design maybe more efficient than the other.

Calculating electric motor efficiency

Electrical motor efficiency is the ratio between the shaft output power - and the electrical input power.

Electrical Motor Efficiency when Shaft Output is measured in Watt

If power output is measured in Watt (W), efficiency can be expressed as:

η_m = P_out / P_in? (1)

where

η_m = motor efficiency

P_out = shaft power out (Watt, W)

P_in = electric power in to the motor (Watt, W)

Electrical Motor Efficiency when Shaft Output is measured in Horsepower

If power output is measured in horsepower (hp), efficiency can be expressed as:

η_m = P_out 746 / P_in (2)

where

P_out = shaft power out (horsepower, hp)

P_in = electric power in to the motor (Watt, W)

Primary and Secondary Resistance Losses

The electrical power lost in the primary rotor and secondary stator winding resistance are also called copper losses. The copper loss varies with the load in proportion to the current squared - and can be expressed as

P_cl = R I² ? (3)

where

P_cl = stator winding - copper loss (W)

R = resistance (Ω)

I = current (Amp)

Iron Losses

These losses are the result of magnetic energy dissipated when when the motors magnetic field is applied to the stator core.

Stray Losses

Stray losses are the losses that remains after primary copper and secondary losses, iron losses and mechanical losses. The largest contribution to the stray losses is harmonic energies generated when the motor operates under load. These energies are dissipated as currents in the copper windings, harmonic flux components in the iron parts, leakage in the laminate core.

Mechanical Losses

Mechanical losses includes friction in the motor bearings and the fan for air cooling.

NEMA Design B Electrical Motors

Electrical motors constructed according NEMA Design B must meet the efficiencies below:

¹⁾ NEMA Design B, Single Speed 1200, 1800, 3600 RPM. Open Drip Proof (ODP) or Totally Enclosed Fan Cooled (TEFC) motors 1 hp and larger that operate more than 500 hours per year

Nicely done and well cited.

But getting back to the original question. There is no intrinsic higher efficiency using a higher voltage source. Many higher power motors use higher voltages and as you accurately cite, higher power motors must exceed more efficient standards to meet NEMA standards. But among motors of equal power, the design of the motor and not the source voltage will determine greater efficiency.

Proven by the FACT that, as I pointed out earlier, a motor manufactured to accept EITHER voltage has the exact same efficiency rating regardless of the voltage it is operated at.

I have no idea why people keep debating this. It is a moot point.

Can someone bring an end to this !! can any 1 tell which was the best answer !! this is taking days !! i am confused

I guess you don't like more information to support a debate.

Well Mr. Maxwell is correct.

The rest is a trivial derivation.

The efficiency is in function the power, and this is afected by losses:

Pcl= R X (I)2

the current is the main value

more current less efficiency

less current more efficiency

But only if R stays constant. I can guarantee that it won't.