Energy Loss Variance in Cables Based on Connected Device Power Supply

It's about the situation of energy loss in the cables from the power supply,
when I connect different devices - with different power:
will the losses in the cables be the same or will they depend on the power of the receiver?

I removed the redundant issue, the next such entry will end with account blocking //kozi966

atto wrote:

will the losses in the cables be the same or will they depend on the power of the receiver?

You answered yourself

The losses depend on the current flowing through the wires according to the formula P=RI^2, where P is the loss power, R is the resistance of the wires and I is the current flowing in these wires. I found this topic https://www.elektroda.pl/rtvforum/topic2899462.html

-> Atto - think of the cable as a resistor / resistor - the greater the current flows, the greater the voltage drop will cause on the cable.

We can write more precisely as we know more details.

atto wrote:

It's about the situation of energy loss in the cables from the power supply,
when I connect different devices - with different power:
will the losses in the cables be the same or will they depend on the power of the receiver?

Do you know Ohm's Law? It is enough to use this knowledge and calculate the example losses for two different values of transmitted power.

The losses depend on the current, and only indirectly on the power of the receiver, you write about the power supply, so you also need to take into account the voltage, at low voltages the problem is intensified, because to obtain the set power the current must be higher, moreover, at low voltages the voltage drops are more annoying and often it is the voltage drop that is the limitation, not the "load capacity" of the wires.

The losses depend on the resistance of the wires (although less than on the current) - an increase in temperature causes an increase in resistance, so heating the wire increases the losses - however small, in the range of temperatures that the wires withstand, it can be up to 40%.

When transmitting alternating current over long distances, the capacitances and inductances of the wires become important: the capacitance causes the flow of additional current, the current itself only gives reactive power, but its flow increases the losses (and they are real) on the resistance of the wires; I have the impression that these losses do not depend on the transmitted power (at least they do not depend much, as long as the length of the cable is much smaller than the wavelength - from about 10% of the wavelength, i.e. from 600km for 50Hz, the phenomenon of wave propagation begins to play a clearly noticeable role , they can change it; from about 1000 km these phenomena start to have a large impact on the functioning of the cable), but only on the voltage, frequency and parameters of the cables - they also occur when no energy is consumed on the receiver's side; inductance causes an uneven distribution of current in the cross-section of the cable, increasing losses for alternating current, and this already depends on the transmitted power. At high frequencies, these problems will also occur with short connections.

So the losses do not depend on the transmitted power but only on the current?

It's kind of weird.
After all, all energy losses are always measured in proportion to the energy that flows in a given system.

The standard formulas for attenuation or scattering in media give an exponential function here:
losses ~ exp(-t/tau), etc.

which is a consequence of the proportionality of losses to energy, which we write with the formula:
dE/E = k = const, k - loss factor,

which is easy to integrate and then we get this exp - exponential distribution.

I don't know how it can be different in electricity... there is probably something botched there, maybe these losses, written as a function of the current itself, are some imaginary - incorrect.

398216 Usunięty wrote:

Do you know Ohm's Law? It is enough to use this knowledge and calculate the example losses for two different values of transmitted power.

Energy loss in a conductor is described by the Joule-Lenz law.
From this law it follows that

atto wrote:

Thus, the losses do not depend on the transmitted power but only on the current

Note that over long distances, electricity is transmitted over very high voltage lines - with constant power, less current is required, thanks to which there are less losses (for heating the air around the wires).

Not only in electricity we have a relationship other than exponential - for example, when scattering light in a cloud, the dependence of the light attenuation on the thickness of the cloud is not exponential.

And in electricity it is not so simple that the losses depend only on the current - not so for alternating current at high voltage - and even for direct current there is insulation leakage.

Another interesting fact: you have two parallel lines, you send energy into one, and along the way there is an "energy leak", somewhere far away you can pick it up from the other; the relationship is sinusoidal!

Yes, I have no idea what this 'current' in the framework of electricity is supposed to be.

According to common definitions, it is supposedly some kind of electron drift in the wire and measured in mm/s.

This is complete nonsense and that's it, and probably hence the further inconsistencies and parodies - losses do not depend on power, etc.

Every kid knows very well that the light turns on immediately after a flick, and then it stays on constantly.

At this crappy speed in mm/s, such a thing would be impossible,
but that there are common analogies to the flow of water in pipes,
where actually this drift - the flow of water is in mm / s, but the pressure changes quickly, from 1000 m / s, that's what was suggested.

Only that in pipes the power is actually proportional to this meager drift - water flow, so it's OK (and losses are also proportional to energy and thus to this drift - flow of water).

However, in the case of electricity the power is probably a trillion times greater - completely inconsistent with this electron drift, so this whole sketch - analogy to hydraulics loses its meaning:

p = 1/trillion.. so much truth and sense in it.

atto wrote:

So the losses do not depend on the transmitted power but only on the current?

And what's strange about it, let's compare with hydraulic systems, where power is the product of flow rate and pressure, or in mechanics, the product of force and speed. Power losses depend on how the energy is transferred and different efficiencies can be obtained with the same power depending on the choice of parameters.

In home conditions, safety issues are decisive, so we use low voltages, far from optimal due to the minimization of losses. In transmission networks, this problem does not exist and there we come to another limitation - at the highest voltages, corona is important, the losses associated with it do not depend on the transmitted power or current, they depend only on the voltage, they will be the same even if we do not connect any receiver.

To be honest, I did not expect such a development of discussion on this topic ;)

It would be best if the author wrote what specific problem he is considering - what voltage, what power of the receivers, etc.

atto wrote:

Yes, I have no idea what this 'current' in the framework of electricity is supposed to be.

According to common definitions, it is supposedly some kind of electron drift in the wire and measured in mm/s.

This is complete nonsense and that's it, and probably hence the further inconsistencies and parodies - losses do not depend on power, etc.

Every kid knows very well that the light turns on immediately after a flick, and then it stays on constantly.

Complete nonsense is only in your perception of reality, I don't have any nonsense - you are trying to "peasant reason" to explain things that are more complicated than "peasant reason" can understand.

As an example, I can give you that the same 12V cable powering a 60W LED strip will have 170% higher losses than powering a 230V 700W drill with maximum load - do you see any absurdity here? Everything makes sense, you just need to know the rules that govern these phenomena, most are so complicated that you can't explain them with flying potatoes with a minus sign.

And where is this energy and power in the drift of electrons with a speed in fractions of mm/s?

Accelerating electrons to reverse speeds is not a problem - even 0.99c was obtained a long time ago, and somehow I have not heard that it costs trillions of times more than the traditional E = 1/2mv^2, and what to talk about mm/s: 1mm/s = 1/300000000000 c!!!!!!!, which is nothing - completely and accurately!

You claim that the losses depend on this shit - electron drift/movement measured only in mm/s (only hypothetically, because I honestly doubt that anyone ever measured something like that in wires!).

Of course it was measured - didn't you pay attention in school during lessons?

As for the free-drift energy/power issue: I discussed energy transfer in a seminar, using sled pulling as an example. It is true that today it would be difficult, snow can be seen only in residual amounts, but maybe we can still imagine what it looked like. I didn't use the sledge anyway, just drew it on the blackboard with chalk.

The current was measured, or some kind of inertial force...
no drift has ever been measured.

I will add, pro forma, another curiosity in this field.

The power/power flux transmitted by the cable is expressed by the formula:
S = E x H

E is here along the wire and H is tangential,
so S has a direction perpendicular to the cable instead of along!

So according to the current theories, energy flows from space and enters the cables ... total parody!

no drift has ever been measured.

It so happens that I was preparing the measuring equipment for the measurements at CERN. ;)

But it was measured much, much earlier - it was in high school physics class.

E is here along the wire and H is tangential,

So according to the current theories, energy flows from space and enters the cables ... total parody!

Not from the Cosmos (we write with a capital letter) - it is part of the transmitted energy that is absorbed in the wire and turns into heat. E has a component parallel to the wire (not "wire", learn the correct spelling), which corresponds to the flux of energy entering the wire, and a component perpendicular, which corresponds to the flow of energy along the wire. If you make a short circuit at the end, then at the end the perpendicular component will decrease to zero - all the transmitted energy will enter the wire and turn into heat. And if you had a superconductor, then the component along the wire will be zero - all the transmitted energy will reach the receiver.

_jta_ wrote:

But it was measured much, much earlier

Yes, probably in 1943 for the purposes of the Manhattan Project. More precisely, it was to calculate the delay of a single energy pulse in a wire of a certain length, in order to perfectly synchronize the ignition of all fuses in a nuclear implosion bomb (Fat Man).

It is quite obvious that these formulas can, at most, describe these losses in the wire, and not any actual energy transfer (apart from the fact that the quantities are wrong: the losses are definitely less than this E x H, so the parody continues! ).

Either way - it's even worse than you can imagine!
1st loss is confused with transmission here
2. the flow return of these losses is incorrect:
the energy from these stats flows out of the wires, not into them, which is what these crappy patterns imply!
3rd and further: the value of losses is incorrect, because it is equal to energy transmission, which is nonsense

4. Finally: according to these improvised models, there is no energy transmission in the wires - only these losses and leaks.

Therefore, only one thing can be said:
currently there is no model of electricity transmission ... there are only empirical crap, guesses and improvisations.

atto wrote:

1st loss is confused with transmission here
2. the flow return of these losses is incorrect:
the energy from these stats flows out of the wires, not into them, which is what these crappy patterns imply!
3rd and further: the value of losses is incorrect, because it is equal to energy transmission, which is nonsense

4. Finally: according to these improvised models, there is no energy transmission in the wires - only these losses and leaks.

ad4. If there is no energy transmission in (or through) wires or wires, how does your computer used to write this crap even work? Do you have power transmission through a cardan shaft or maybe a water pipe?
Finally, I will ask if you are making such revelations at the modest Polish Technical Forum "Elektroda" and expect to take over the chair of physics at the Massachusetts Institute of Technology? Because experts like you have just arrived from the State University of Kansas to work in Mińsk Mazowiecki .... etc., etc.

18 Feb 2018 21:38 - The delay of the pulse in the wire is not related to the electron drift speed.

18 Feb 2018 22:08
I'm ignoring the fact that the sizes are wrong here - As far as I know, they are correct - you got the accounts wrong?

these formulas can, at most, describe these losses in the wire, not any actual energy transfer
They describe both, which I wrote about, but to check it, you need to count, and I don't think you know very well.

1st loss is confused with transmission here - You're probably wrong, but what can you do about it?

2. the flow return of these losses is incorrect: - And check, the sign is easy to confuse.

3rd and further: the value of losses is incorrect, because it is equal to energy transmission, which is nonsense
When the calculations are done correctly, nothing like this comes out. Show your calculations, there will be an error.

currently there is no model of electricity transmission ... there are only empirical crap, guesses and improvisations.

And without a correct model, how could someone design such an advanced computer as they are being made today?
Models certainly exist, and there are people who know how to use them, but maybe you are not one of them.

There is another problem: there are many models, they look completely different from each other, and it's hard to see that they give the same thing. ;)

For example, this is the case: a charge moves with constant acceleration (in co-moving inertial frames, but I don't know if you understand the term); according to one model, such movement causes electromagnetic wave radiation (and the model determines its amplitude); according to the second, it does not (the model specifies that the energy radiated during such movement is zero); and they are compatible with each other.

atto wrote:

Yes, I have no idea what this 'current' in the framework of electricity is supposed to be.

According to common definitions, it is supposedly some kind of electron drift in the wire and measured in mm/s.

Confusion with confusion. Let the drift of electrons in the wire be a drift, and the "current" you are asking about is an electromagnetic wave. If you are familiar with differential and integral calculus, I recommend Maxwell's equations. For example http://www.iwiedza.net/materialy/m042.html

Somehow you're not surprised that the radio signal at noon, that is, announcing twelve o'clock, can be heard exactly at the same time in Warsaw and Krakow. And you are surprised how fast the light turns on...

This whole discussion makes no sense, your level of knowledge of the theory is low, for now you have to go to school, they teach it there.

Sure, there's nothing to discuss here...

I explicitly asked about the dependence of the loss on the transmission lines on the power of the receiver,
and what did i get in response?

Absolutely nothing! It omits naive attempts to derail the subject, or to disqualify the author himself, etc.

And this was just a medium-light test for the competence of electricians;
which I think you all failed here - and badly, unfortunately.

Regarding Maxwell etc. sketches:
it is obvious that: E x H must be in the direction of energy transmission, so E must be radial - perpendicular to the conductor, not along!

atto wrote:

I explicitly asked about the dependence of the loss on the transmission lines on the power of the receiver,
So what did I hear in response?

You ask like a lamer, without defining any boundary conditions, so why are you surprised that you get the same answers?
It's like asking if two days of rain will be followed by a flood. Answer the exact question yourself.

And usually E is roughly radial - haven't you noticed that yet? But that's not the topic, so I'm not going to explain it to you in this topic.

And as for the information about the losses and what they depend on, you probably received more than you can understand - especially with the approach to the issue and the interlocutors that you presented.

The question is extremely simple: what are the losses in the transmission lines... etc.

You don't know, you don't know the dependence of losses on transmitted power?
Well, good night - what's there to talk about?

Are you complaining that you don't know?
Well, maybe measure something there, or learn... well, I don't know what more advice I can give you - I thought you knew something about electricity, so I'm sorry you don't.

atto wrote:

The question is extremely simple: what are the losses in the transmission lines... etc.

Transmission lines are lanes or links, not lines.
And because you are rude to the answerers and extremely conceited, in addition you still do not define the issue in technically understandable language, I close the topic. It's a shame to bother people.