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Discussion Starter #1
Hi. I don't own a generator, but my friend does, and I think his generator would be considered typical for the time at which he purchased it--in 1999, just before Y2K. It is capable of powering about half his house, and goes on automatically when the power is lost.

He mentioned to me that during the recent crisis--his area ultimately was without power from Hurricane Sandy for about a week--he and his wife had deliberately cut back on electric usage to conserve fuel (propane) because there was a real possibility that they wouldn't be able to get a replenishing of their supply due to impassable roads, etc.

I expressed surprise, because I thought that most "typical" generators ran at a constant rate, whatever the actual electrical demand might be; i.e. it was either on or off, so that it would be impossible to "conserve fuel" by lessening demand. He maintained that, no, he thought that a typical generator operated like a car motor, and the greater the demand, the faster the generator would go, and the more fuel it would consume per time unit. Neither one of us has any evidence to support our position, so I'm turning to you guys to tell us what the facts are.
 

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I expressed surprise, because I thought that most "typical" generators ran at a constant rate, whatever the actual electrical demand might be; i.e. it was either on or off, so that it would be impossible to "conserve fuel" by lessening demand. He maintained that, no, he thought that a typical generator operated like a car motor, and the greater the demand, the faster the generator would go, and the more fuel it would consume per time unit.
In the world of generators, there are two main types: traditional and inverter.

Traditional generators are like you describe; to make usable, 60Hz power, they must turn at exactly 3,600 rpm, which is wide-open-throttle on most. Some models will throttle down to idle speed when they detect NO load at all, and then go back to full throttle when a load is applied.

Inverter generators work differently. They start by making high-voltage AC power, then run it through a converter circuit, which changes it to DC power. Next, it is run through an inverter circuit, which flips it back to AC. Because of this process, inverter-type generators do not need to run at 3,600 rpm, and, as your friend suggested, can adjust the throttle speed to match the load requirements. With no load, they run at idle.

Traditional generators are less expensive to make, inverter models, depending on the quality of the inverter parts, are usually more costly.

Depending on the requirements, a traditional model will often do okay, if used in emergency stand-by power situations. If the generator is going to be used more frequently, an inverter-type model will in the long run, require less service, run quieter, and burn less fuel.

[email protected]
Caveat: I work for Honda, but the preceding is my opinion alone.
 

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The more demand put on the generator the more fuel you are going to use. if you look at generator manual it will tell you at 1/4 load, so much fuel, 1/2 load, so much, and full load so much. His generator needs to turn at a constant speed. As he adds more load to the generator the engine has to make more torque to spin his generator thus needing more fuel for the more torque. Less load less torque, his engine doesn't need to work as hard.
 

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Discussion Starter #4
Dqalex, if I understand you correctly, then the distinction [email protected] makes between the two types of generators is irrelevant to my question, because the traditional type of generator, that must run at a constant 3600 rpm, will have to work harder with a greater electrical load to attain that 3600 rpm and thus use more fuel.

[email protected] do you agree with Dqalex?
 

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Dqalex, if I understand you correctly, then the distinction [email protected] makes between the two types of generators is irrelevant to my question, because the traditional type of generator, that must run at a constant 3600 rpm, will have to work harder with a greater electrical load to attain that 3600 rpm and thus use more fuel.

[email protected] do you agree with Dqalex?
I would bet your friend has a traditional 3600 RPM or maybe an 1800 RPM. I would bet its most likely not and inverter type generator. Even with a inverter type generator its still all about the load for fuel cost. I agree with Robert about inverter type Generator's. The less load the slower they turn. My Honda EU6500is is an inverter type generator and with a light load on eco the RPM's go from 3300 RPM's down to around 2200- 2300 RPM's.
 

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Discussion Starter #6
Dqalex, would you do me an enormous favor?

I've been thinking about your explanation, and doing a little reading about generators. The basic principle is that they create a current by moving a wire through a magnetic field, with the movement caused by, for example, propane-fueled rotary motion. The amount of current would depend on the speed of the rotation, and the speed of the rotation would appear to depend on the mechanical properties of the generator and NOTHING ELSE, including the use, if any, to which the electricity it produces is put. It seems to me that once that current is created it doesn't matter (from the standpoint of the generator) whether it simply "flows" or does actual work powering electrical devices. Picture an enormous hydroelectric generator--it creates electricity which it sends down transmission lines to our homes and whether or not people use that electricity, or how much they use it, is immaterial to the hydroelectric generator, which produces electricity at a rate dictated strictly by the flow of water through it. If more people use air conditioners on a given day, that doesn't make it "harder" for the generator to produce a given amount of electricity--it produces what it produces, and the amount of that electricity that is used productively seems irrelevant to the "effort" (or fuel) required to produce it.

Of course, everything I just said could be completely wrong. So Dqalex, what I'd love you to do is copy and paste the part of your generator instruction manual that you described as saying, " if you look at generator manual it will tell you at 1/4 load, so much fuel, 1/2 load, so much, and full load so much." Those words could be interpreted in several ways, so I'd like to see them in context. Could you do that? I'd appreciate it, because now I'm determined to get to the bottom of this.
 

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For traditional design generators, a fuel consumption figure that states "at 50% load" merely means the generator was run for X hours, and the time it had an actual electrical load and ran at wide-open throttle was X/2 hours. A an example would be a freezer with a compressor that was plugged into a generator with an Auto-Throttle feature, and the compressor only ran for 30 minutes but the generator engine was running for a full hour.

Inverter generators fuel consumption is based more on the actual load required. If you plugged in a 1,500 watt electric heater into a 2,000 watt (continuous) generator for X hours, the fuel consumed would be "at 75% load" since 1,500 is 75% of 2,000.

For simple calculations, just think in terms of how much fuel cost per hour does the generator require to power the devices in your environment? Generally speaking, and inverter type that's rated in excess of the total load will cost less per watt-hour to run than a traditional-design generator.

The only time they would be close in cost is if they were both rated at the same continuous wattage, and your electrical load were equal to that. In such a case, both types of generator would be running at wide-open throttle.

[email protected]
Caveat: I work for Honda, but the preceding is my opinion alone.
 

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Discussion Starter #9
At last the mist clears, the paradoxes resolve themselves!!!!

Dqalex I followed your link, and made the following discovery, whose meaning I was able to grasp only because of [email protected]'s tutelage:

From the HondaEU6500i Super Quiet Generator web page, describing some features of your generator, Dqalex:

"Inverter - stable power for computers and more"

Thanks to Robert, the sight of the word "inverter" meant that your generator Dqalex is NOT the low-end traditional generator that my friend has, but the more sophisticated type Robert was discussing, whose principal advance is that it VARIES ITS OUTPUT WITH DEMAND and thereby saves fuel!!!!

So, yes, Dqalex, you were certainly correct about YOUR generator's fuel consumption varying with the load placed upon it, but you were mistaken in extrapolating from that to ALL generators.

Robert, I thank you very much for providing me with these crucial pieces of information and explanations. If I may, I'd like to ask you one direct question. Is the following "model" correct?

I conceive of the work the TRADITIONAL (NOT the inverter type!) generator is doing as it rotates as equivalent to the work done by someone in compressing a spring. When you release the coiled spring it may cause a 10 lb. Jack-in-the-box to pop up or it may uncoil without doing anything more than jostling a few air molecules. But whatever is done by the energy of the uncoiling spring, whether a lot or nothing, has ABSOLUTELY no effect upon the amount of work done by the person in compressing the spring in the first place. And in exactly the same way, the work done by the generator in spinning around and thus creating energetic electrons is totally unaffected by whether that electricity powers compressors or heaters or nothing at all. Exactly the same amount of propane will be used to operate the traditional generator for an hour no matter how that electricity is used, or if it is used at all. And so my when friend and his wife, in the aftermath of Hurricane Sandy, killed themselves to conserve electricity to save propane they were in fact not saving a SINGLE DROP OF PROPANE.

[email protected], is the preceding paragraph completely right? Please correct any places that I have erred.
 

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At last the mist clears, the paradoxes resolve themselves!!!!

Dqalex I followed your link, and made the following discovery, whose meaning I was able to grasp only because of [email protected]'s tutelage:

From the HondaEU6500i Super Quiet Generator web page, describing some features of your generator, Dqalex:

"Inverter - stable power for computers and more"

Thanks to Robert, the sight of the word "inverter" meant that your generator Dqalex is NOT the low-end traditional generator that my friend has, but the more sophisticated type Robert was discussing, whose principal advance is that it VARIES ITS OUTPUT WITH DEMAND and thereby saves fuel!!!!

So, yes, Dqalex, you were certainly correct about YOUR generator's fuel consumption varying with the load placed upon it, but you were mistaken in extrapolating from that to ALL generators.

Robert, I thank you very much for providing me with these crucial pieces of information and explanations. If I may, I'd like to ask you one direct question. Is the following "model" correct?

I conceive of the work the TRADITIONAL (NOT the inverter type!) generator is doing as it rotates as equivalent to the work done by someone in compressing a spring. When you release the coiled spring it may cause a 10 lb. Jack-in-the-box to pop up or it may uncoil without doing anything more than jostling a few air molecules. But whatever is done by the energy of the uncoiling spring, whether a lot or nothing, has ABSOLUTELY no effect upon the amount of work done by the person in compressing the spring in the first place. And in exactly the same way, the work done by the generator in spinning around and thus creating energetic electrons is totally unaffected by whether that electricity powers compressors or heaters or nothing at all. Exactly the same amount of propane will be used to operate the traditional generator for an hour no matter how that electricity is used, or if it is used at all. And so my when friend and his wife, in the aftermath of Hurricane Sandy, killed themselves to conserve electricity to save propane they were in fact not saving a SINGLE DROP OF PROPANE.

[email protected], is the preceding paragraph completely right? Please correct any places that I have erred.
Still not right. Take a look at this one is a home standby. Look at the gas at 1/2 load. Briggs & Stratton Standby 7kw Home Generator LP w/ 50amp ATS #40298-R +1918 | eBay
 

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At last the mist clears, the paradoxes resolve themselves!!!!

Dqalex I followed your link, and made the following discovery, whose meaning I was able to grasp only because of [email protected]'s tutelage:

From the HondaEU6500i Super Quiet Generator web page, describing some features of your generator, Dqalex:

"Inverter - stable power for computers and more"

Thanks to Robert, the sight of the word "inverter" meant that your generator Dqalex is NOT the low-end traditional generator that my friend has, but the more sophisticated type Robert was discussing, whose principal advance is that it VARIES ITS OUTPUT WITH DEMAND and thereby saves fuel!!!!

So, yes, Dqalex, you were certainly correct about YOUR generator's fuel consumption varying with the load placed upon it, but you were mistaken in extrapolating from that to ALL generators.

Robert, I thank you very much for providing me with these crucial pieces of information and explanations. If I may, I'd like to ask you one direct question. Is the following "model" correct?

I conceive of the work the TRADITIONAL (NOT the inverter type!) generator is doing as it rotates as equivalent to the work done by someone in compressing a spring. When you release the coiled spring it may cause a 10 lb. Jack-in-the-box to pop up or it may uncoil without doing anything more than jostling a few air molecules. But whatever is done by the energy of the uncoiling spring, whether a lot or nothing, has ABSOLUTELY no effect upon the amount of work done by the person in compressing the spring in the first place. And in exactly the same way, the work done by the generator in spinning around and thus creating energetic electrons is totally unaffected by whether that electricity powers compressors or heaters or nothing at all. Exactly the same amount of propane will be used to operate the traditional generator for an hour no matter how that electricity is used, or if it is used at all. And so my when friend and his wife, in the aftermath of Hurricane Sandy, killed themselves to conserve electricity to save propane they were in fact not saving a SINGLE DROP OF PROPANE.

[email protected], is the preceding paragraph completely right? Please correct any places that I have erred.
I tried to post a link for a NG Generator. its the same. The more load the more gas it uses. Your neighbor is right.
 

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The amount of fuel burned is usually relative to the load, even on traditional generators. Here's why:

When there's little or no load on the circuit, the generator's governor keeps the engine spinning at 3,600 rpm (or very close). The throttle plate may only need to be open 40% to keep the speed steady.

Now when you add a load, say one that is 50% of the rated capacity of the generator, the throttle has to open up a more (maybe 75%) to meet that demand and maintain 3,600 rpm. With a wider-open throttle, the fuel consumption increases.

Exactly how much depends on the efficiency of the engine, ambient temp, and a few other factors.

So reducing the load will cause the throttle to close a bit, and fuel flow to drop. However, such a design is never going to be as responsive or efficient as an inverter-style generator.

Imagine your car. Sitting in PARK, how much fuel is burned to hold the gas pedal so the engine turns @ 2,500 RPM? Now, if you shift to DRIVE and get out on the road, how much fuel is burned to keep the engine turning 2,500 rpm?

[email protected]
Caveat: I work for Honda, but the preceding is my opinion alone.
Caveat: I am not an engineer!
 

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Discussion Starter #13
Robert, first thank you for your intelligent and informed responses.

I hope you don't mind pursuing this with me for a bit, because I want to find the exact way in which my thinking has gone awry, if it has.

There are two possible models for viewing what happens with the generator in this situation.

Model 1 (as described in my last post):I conceive of the work the TRADITIONAL (NOT the inverter type!) generator is doing as it rotates as equivalent to the work done by someone in compressing a spring. When you release the coiled spring it may cause a 10 lb. Jack-in-the-box to pop up or it may uncoil without doing anything more than jostling a few air molecules. But whatever is done by the energy of the uncoiling spring, whether a lot or nothing, has ABSOLUTELY no effect upon the amount of work done by the person in compressing the spring in the first place. And in exactly the same way, the work done by the generator in spinning around and thus creating energetic electrons is totally unaffected by whether that electricity powers compressors or heaters or nothing at all. Exactly the same amount of propane will be used to operate the traditional generator for an hour no matter how that electricity is used, or if it is used at all.

Model 2 (which I think would be along the lines you laid out, Robert) In this view, imagine someone is hand-cranking a generator at a constant rate of rotation. The Incredible Hulk comes along and grabs the cranker's arm and partially restrains him. The cranker has to expend much more energy to maintain that constant rate of rotation.

So the question is: Why would the actual situation with a traditional generator be like Model 2 and not Model 1? Accepting your assertion that in fact Model 2 IS correct, I want to understand why Model 1 does not apply, how it goes awry.

To your example of the automobile, I would respond as follows: First, I'm not sure that the RPMs remain constant, but even if they do, the driver is engaging gears so that the work being done is increasing. If you are pedaling a bicycle and are rotating the pedals at a constant rate, as you shift from 1st to 3rd gear you must dramatically increase the effort to maintain a constant rate of pedal rotation because now each rotation of the pedal is translated into a bigger portion of the rotation of the bicycle wheel. So yes, this is equivalent to The Incredible Hulk restraining you, and of course more "fuel" (calories in your body) must be expended. But that's because of the physical interconnection between your pedaling and the gears (1st or 3rd) turning the wheels. And in fact, even if you don't shift gears, if you stay in 1st gear and move from level ground to a hill, you'll have to expend more effort to maintain a constant rate of rotation of the pedal because the pedaling and wheel-turning are directly, physically connected, and can almost be viewed as a single act with multiple parts. Thus if you increase the work of the task (uphill rather than level movement) you'll need to increase the effort of pedaling to maintain a constant rate of pedal rotation.

But if we consider the generator situation, it strikes me as entirely different. The generator's rotary motion creates a current, and the energized electrons of this current, it seems to me, are "on their own". That is, they go off and what they do or don't do in powering electrical devices DOES NOT FEED BACK and affect the rotary motion of the generator. Are you suggesting that if the electrons power a heater, then those electrons would somehow backwardly interfere with the rotation of the generator, so that it would become harder? What is the physical mechanism that would do this?

I don't see that there is such an interconnection. That's why I compared it to compressing a spring. I think, Robert, you would agree that what happens after you release the coiled spring has no relevance to how hard it is to compress the spring in the first place. Right? The generator's release of energized electrons is like the uncoiling spring--what those electrons do (what the uncoiling spring does) has no bearing on the work done to energize the electrons (compress the spring) in the first place.

Here's another analogy Robert: Imagine you turn on the gas jet of a stove--let's suppose you turn it 1/8 of a rotation, causing the flame to rise to, let's say, a height of one inch, yielding a given amount of energy. It doesn't matter if you put a pot of water over the flame, or poach an egg, or make my favorite, french fries, or just let the flame burn with nothing on the stove. The exact same amount of gas would be used to create that one-inch high flame because the task to which the flame is put (if any) does not "feed back" to the flame and make it harder for the flame to reach its one-inch height. And in the same way, it seems to me, the task to which the electrons are put does not "feed back" to the generator of those electrons and make it harder for that generator to energize them.

But I freely admit this analysis may be wrong. I just need to know how and why.
 

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Graviton,

There is a feedback into the generator. It has a governor hooked to the throttle. While it may be turning at the same speed, usually 3600 rpm, it must increase the amount of power by opening the throttle to maintain that speed. It's the same principle as you going up the hill on a highway - not downshifting (keep it in the same gear). If you want to keep the same speed you press down on the accelerator. If the hill becomes very steep then you can't hold speed even with the pedal to the floor - you've overloaded the engine. It can happen to a generator too.

Energy is neither created nor destroyed, it just changes form. The energy in the fuel is converted by the generator's engine into mechanical energy. The generator then converts it into electrical energy. When you use this energy to produce heat or light, you are converting the energy again. All this energy has to come from somewhere, and it comes from the fuel being consumed.

An inverter generator still must use more fuel when load increases. There is NO difference in that aspect. There is no mystery in either type of generator, burning fuel produces electricity. An inverter generator can be more efficient because it doesn't need to keep the engine turning at high rpms under light load but it will still use more energy as loads increase.

Using the spring as an example. As you press down you are storing energy, potential energy. Once it is released it is kinetic energy. You had to expend more energy (work = force X distance) to compress that spring further, and once you let go, more energy was released.

Reducing load on the generator reduces fuel consumption because the engine doesn't have to work as hard to turn the generator over. It's like driving at 65 mph or 35 mph. You'll get better mileage at 35 because the engine doesn't have to work as hard - less wind resistance for one.

Hope it helps.
 

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Generator engineers and designers calculate a sweet-spot for the unit to operate, given the expected loads.

For example, a traditional generator will likely put out 125+ volts when connected to a light load, then put out 120 volts with a medium load, and an acceptable 115 volts when fully loaded.

It's the governor that moves the throttle a bit to keep up with the demand. The weights in the governor are pulled closer to the shaft (gravity) during a drop in speed, and centrifugal force causes them to move away from the shaft due to centrifugal force when there's an increase in engine speed. There's a simple mechanical link that forces the throttle open or closed, depending on the engine's speed.

So, when a load is applied, the electrical draw will cause the rotor/stator part of the generator to slow down/drag a bit (as well as heat up), and as the rotor is directly connected to the engine, the braking effect makes the engine slow down. This drop in speed is detected by the governor, which moves the throttle open a bit more (burning more fuel) and getting the speed back closer to 3,600.

It's all analog/mechanical, and thus subject to some variation. This is why the designers try and calibrate everything to provide a sweet spot of voltage, frequency, and amperage that suitable for the expected loads.

[email protected]
Caveat: I work for Honda, but the preceding is my opinion alone.
 

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Discussion Starter #16
To Robert and aandpdan

Gentlemen, the combined force of your words is irresistible!!!! Your powerful marshalling of the facts has bludgeoned me into the following confession:

YES, yes, I acknowledge that the amount of fuel consumed by even the traditional generator (maintaining a constant 3600 rpm) varies with the electrical load placed upon it!! It's obvious that you both are speaking from too much direct knowledge and experience for me to continue to question that fact, EVEN THOUGH UNTIL NOW IT HAS SEEMED HIGHLY IMPLAUSIBLE!!

So, in accepting this truth, I am forced to carefully reexamine my admittedly unsophisticated understanding of electricity and its sometimes strange ways. And I have had to abandon some assumptions about what is and is not possible. So after some thought I want to offer two possible scenarios as to how the changing current feeds back to the generator to alter its function--just the kind of feedback I thought was out of the question until today.

Let's take the simplest possible situation, where the generator is operating at full capacity, with a wide-open throttle, using the maximum fuel to produce the maximum electricity, all of which is being utilized by Device X that is hooked up to it. Now we lower the power of Device X, reducing the current flow. We have reached the crucial moment: exactly what happens, physically, to the electricity at this instant that causes the generator to reduce the amount of fuel being consumed while maintaining 3600 rpm???????

Scenario A (This seems the less likely of the two to me): When we turn down the power of Device X, we are increasing the resistance to the current flow, and (I speculate) the portion of the electricity produced by the generator that encounters this resistance actually flows BACK to the generator. In arriving back at the generator it acts as it would when entering any other device--it exerts a force, and in this case the force slightly speeds up the rate of rotation. At this moment the governor that you two have discussed in your posts kicks in to counteract this speed up by reducing the fuel to the generator, etc. I doubt this scenario simply because I've never heard or read any account of electrons behaving in this way (i.e.flowing backwards).

Scenario B: In this version, when we turn down the power of Device X, increase the resistance, and lessen the current flow that Device X is demanding, the generator instantly stops applying a force to those electrons that no longer have the opportunity to be part of the current. Because the generator has stopped dissipating its momentum on these electrons, it retains some velocity and moves slightly faster than before. And, of course, the governor steps in to counteract this speed-up by reducing the fuel supply, etc. I must admit this scenario, though more likely than the first, makes me a little uneasy, because it's a bit surprising to me that the generator would only energize electrons that have the opportunity to flow as a current. This was the sticking point for me when I questioned the feedback.

Speaking of feedback, Robert and aandpdan, I eagerly await yours regarding my two scenarios. Does either strike you as the likely explanation, do you have a third I haven't thought of? I welcome any critique you see fit to offer.(And of course anyone else out there who has anything to say, I welcome your comments as well.)
 

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Graviton,

Voltage is the amount of "push" behind the electrons. Current is the "flow." The generator is always "pushing" (energize electrons) but without a circuit there is no flow.

When the power requirement drops, the engine is able to turn easier. The engine governor will begin to close the throttle slightly to maintain the correct rpm (usually 3600 rpm). Your scenario B.

Say for example you open the circuit. The electrons stop flowing, the engine RPM will increase, the governor will the close the throttle reducing fuel flow.

Now, put the max load on the generator, say a resistance heater. The electrons will rush through the circuit. As they go through the heater they face increased resistance and produce heat. As the load increases the generator works harder and the throttle opens further to compensate.
 

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Discussion Starter #18
Hi aandpdan,

This is perhaps a small point but your saying that the generator continues to energize the electrons (in applying voltage) seems to completely defeat the whole point of the argument. If the generator continues to transfer energy from itself to the electrons then there would be no reason that the generator's rotation would speed up, and thus no reason for the governor to cut back on its fuel in order to reduce the rotation rate back to 3600 rpm.
 

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Hi graviton,

Voltage is potential.

The electrons being "energized" in a complete circuit move from an area of greater electrons to an area of lesser electrons, nature likes things balanced. However, only a few electrons can at a time can get through a wire, whether it be the windings in a motor or the filament in light bulb. As the electrons move, it takes energy to "push" them along. The resistance to them moving in most cases is wasted energy - heat.
 

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Discussion Starter #20
Hey aandpdan (I've had to devote several hundred thousand neurons to mastering the spelling of your nickname!!)

Actually, I think we're now in agreement. Yes, voltage is still being applied to all the electrons, including the ones that are no longer part of the current as a result of the power having been turned down on Device X. But the generator is not transferring its kinetic energy any longer to those suddenly-excluded-from-the-current electrons, which causes the generator to briefly speed up its rotation rate until the governor can reduce the flow of fuel and bring it back to 3600 rpm.

So I have a clear idea of that now (and I'm appreciative of the role you and [email protected] played in driving me to abandon my original misconceptions), although I do still have a sense of uncertainty about what is going on with the electrons when they are "under electrical pressure" but are not part of a current. Electricity is conventionally compared to water flow, so let's consider a situation where you have a sink with the faucet turned completely off. The molecules of water are under pressure, and the instant that faucet is turned on they will spurt out---but what about their state before the faucet is turned on. They have not acquired any kinetic energy (which is why the electrons in that situation allow the generator to speed up, and then be throttled back to save fuel in maintaining 3600 rpm) but it's clear that "something" is happening to them. The fact that the water molecules are unable to move means no KINETIC energy is being transferred to them, but clearly a force is being continuously applied to keep them in that pressurized state. Now applying that concept to the electron situation, how do you parcel out the amount of energy (or fuel) necessary to apply the force that merely keeps the electrons in the pressurized state versus the amount of fuel necessary to apply both that force and also the force that drives them in currents of various sizes?

So for example, if the generator has no electrical devices active at all (zero load) but is spinning at 3600 rpm and creating its normal pressure (voltage), what amount of energy is necessary for that versus spinning at 3600 rpm while producing, say 10 amps of current? In thinking about that, it seems that there never would literally be zero load, since amps=volts/ohms so with anything less than infinite resistance there'd always be some current. So as I type my question, I think I see how to derive the answer: Find out how many ohms are involved when you turn off all the devices on the circuit, then calculate the amps in that state (using the voltage the generator is producing), then determine the wattage, amps X volts. Then take the amps when Device X is on, multiply it by the voltage, and voila!

It seems that if we use 120 volts, and some arbitrarily high resistance that would effectively keep the devices "off" (would 100 ohms be reasonable? I have no idea), then we have 1.2 amps X 120 volts=144 watts of power consumed by the generator when it's not supplying current (for all practical purposes) to any devices. And 1200 watts of power when it's supplying 10 amps at 120 volts. So the generator would consume only 144/1200=0.12, only 12% of the fuel when not powering any devices compared with supplying 10 amps. But that assumes my choice of 100 ohms was reasonable. I'd like to know: What is the correct amount to use?

Wait a minute, that can't be right. I'm realizing that not only didn't I take into account different levels of efficiency for the generator at different wattages, but, much more importantly, what about just the idea of a generator as a motor, spinning around without even producing any voltage at all--wouldn't that have to be calculated as well and considered a "base" state? In fact, that would be a very significant amount of energy I imagine.

(An important aside: thinking back to the water analogy--- Clearly NO water whatsoever is getting out of the faucet, and yet force is being applied to keep the water under pressure. So what do you do to calculate the force in that situation? In the electrical situation, we're using some hypothetical amperage that would still flow with high resistance. Now that I apply the water analogy, I question whether that is really a sound analysis!!)

So we really have three separate fuel issues (maybe more, I may be missing some!) First, the generator just as a motor, requiring energy (fuel) even without producing voltage. Second, we have the generator producing voltage but not powering any electrical devices. Third, we have the generator powering a 10 amp device.

Oh my God, the complications never end!!!

Anyone who can provide enlightenment is welcome, in fact is eagerly sought! I really want to understand every detail of this.
 
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