Where Does the Energy Go?

Nothing. The energy already left.

"The generator is then - Not a generator anymore . It is a rotating machine that will rotate as long as the prime mover driving it rotates."

ahhhhhh - thank you - beautifully described

As said before, this is oversimplifying.

The generator is composed of different components that work together to fulfil the job of converting a mechanical energy from the prime mover (diesel engine for example) into a useful electrical energy. Therefore, there is a control device that can be compared to a water tap, which is opened more or less to allow more or less mechanical energy to be converted into the electrical energy: The AVR (Automatic Voltage regulator).

When you open the outgoing circuit to stop consuming electric energy, the tap will be closed enough to just allow what is needed to maintain the system ready for the next demand. Therefore, No Energy goes Nowhere if Not asked for!

{ I have simplified the description for you}

A generator always has a load. A short circuit is like a zero ohm resistor, and an open circuit is like a many megohm resistor. If you rotate a generator with its output open, the current flow will be micro, nano, pico or femto amperes depending on the actual resistance of the alleged "open circuit." Most of the energy put into the generator will be absorbed in the generator by several forms of friction, but there will always be an electrical output.

The most the energy use in that form comes to an end. The load on the generator will be less so less energy will be used to turn it.

Nicely put - thank you again!

questionsquestions are you still at school? Or are you being deliberately annoying.

I am with full agreement with Tony since a professional Engineer will not ask this type of silly questions other than students without any idea about electrical engineering.

We welcome questions from all people.

Nevertheless, this forum is not an enciclopaedia (or Wikipaedia) for people who need to start from scratch on a subject. Some questions could be searched on the internet or in libraries so that the basic concept is reached with more details. After that, you could ask questions that still bother you or were not clearly explained.

Otherwise, your naive questions will trgger suspicion that you might be trying to play arround or moking us by asking such simply out of range questions.

You had some replies (Thanks to those contributors) that seem to have satisfied you. Then call it a day and ignore the other remarks if possible.

I have stated this before and I state it again, we are all here to help each other with problems, questions and understanding. We are not all experts in the field as it is so diverse. We have all paid a fortune for learning, have all gained experience and still have a lot of value. There is a vast skill shortage world wide, and I agree, there is a lot of knowledge that should be shared, but at the same time, you should be searching as we have done. This forum seems to be used as a 'instant learning programme'. People in the field doing jobs they have no knowledge of at all and yet, getting much help and guidance from this forum, all free. So have a heart and understand, we are all good in our chosen fields of expertise, and there are many questions crop up here that are 'homework questions', with no thought put into them. Maybe should should state your age and vocation in life, then we may be able to help you better without sarcasm. But help, I am sure you will always get. Looking forward to your reply as to what you do and where you are. And don't take it so hard, you learn here about life too.

99% would ask "whats a generator?"

When there is no load on generator the power input to the engine is spent in rotating the engine itself(like a car stationary but engine running) & in rotating the rotor of generator,friction & windage losses.

The generator would then only have an energy potential but would not be putting out energy.

By design the generator is always producing "energy" in the form of electro magnetic forces while spinning, due to there being inductive coils present. This is occuring regardles of what is hooked to the leads. As the generator slows to a stop these fields reduce in strength until they drop to 0 (generator at full stop). By saying that it is not there until you hook something to the leads is like saying electricity doesn't appear until you plug a lamp into a socket.

to be certain, there is still some energy spent when a gen set is disconnected, through the control circuits and core losses etc. The difference between POTENTIAL energy and ACTUAL energy is, that when disconnected the generator produces a small amount of actual energy but has the potential to produce much more when a load is applied. I have the potential to hit something with a hammer, but the energy delivered by the strike is not real until the strike happens. Thus the suggestion that the large energy does not exist is relatively accurate in the context of being disconnected, it is now only a potential energy.

In terms of electricity, the voltage ( potential ) is there, but the actual energy is delivered by the current. Disconnected electrical outlets have only potential. A touchless voltage sensor uses leakage current to indicate the presence of a voltage; and the "circuit" will show a minute delivery of energy when the sensor is brought near.

It powers my Gold Wing.

Having re-contemplated the question, this has nothing to do with the running generator. The question is, 'what happens to all the energy that was running through the circuit?' Why are we concerned with the generator?

The answer is; the electrons stop vibrating in the circuit as the energy source is removed, and the circuit is no longer energised, (no voltage no current). But, the ambiguity of the question has had all explaining how a generator works. Clever question, very misleading.

Home work done, 10 points.

It is secretly stolen by Tesla Motors and Chevy Volt to charge batteries, run hybrid cars, laptops and cell phones. The mystery solved! Good work Watson!

Actually, Disconnecting the generator at both ends (the 2 poles) will have the effect of making the current still vibrating forward and backward for a very short time until it dissipate the energy left in the circuit. this is very quickly dissipated, maybe in less than a cycle. ...

Wow I can't believe you caught me out - are you perhaps the real Sherlock Holmes?

No.

When you break the circuit and the generator keeps running, the generator still produces voltage at its output, but no energy is produced. As you may know, energy is: E = P x t = V x I x t. As you see, when you disconnect the generator you have I=0, hence E=0. So, no energy is produced.

Although generator doesn't produce energy,the engine's power is wasted in rotating itself,the generator,friction,windage and noise.

Exactly G.K.

But to make the concept clearer, lets consider an amount of water in a tank and the following equivalence:

electrical voltage ≡ height of the tank raised over the ground

electrical current ≡ flow of the water from the tank to the ground

generator ≡ pump pushing the water from the ground up to the tank

The pump is special in the sense that when it works, it guarantees that there is a given amount of water in the tank. If it doesn't work, then the tank will be emptied through the input (pump's) tap. As long as there is water in the tank, there is a potential to produce work, but unless the output tap of the tank opens, no actual work is produced. Nevertheless, even when the tank's output tap is closed, the pump still consumes a small amount of energy.

Similarly in the equivalent electric circuit, even if there is no load connected, the generator still consumes energy to sustain a boring electrical field that just minds it's own business.

Buck to the hydraulic equivalent now, in case the tap opens, then the pump will have to consume EXTRA energy, to replenish the water that flows out of the tank and overcome any friction of the water passing through itself, the input & the output pipes (I assume a closed system). Similarly, the electric generator will have to work HARDER in case a load is connected at the output. As soon as we connect a lamp, per instance, the generator will be extra stressed (and if not adequate, will also drop the output voltage).

Concluding, it is the difference of consumed energy before and after letting the water or the electrons run about which appears to us as "useful" energy, i.e. energy that produces work, and in order to get the useful work going, we need to feed the generator/pump with at least the same amount of input energy.

Incredible . . . every once and a while I truly appreciate the value of a practical experiment, and the intuitive understanding it gives you. I see a lot of complicated answers incorporating math, analogies, etc.

When I was in middle school we learned about electricity, and the teacher let me take home a broken hand crank generator (looked like a pencil sharpener) that had a light attached. My Dad (who got me started in electronics) got it working and did a demonstration with me. He disconnected the light from the generator, and told me to start cranking. As I was cranking he then plugged the light back in, it illuminated, and it became much harder to crank the generator, because there was an electrical load on it.

So the practical answer is, when you disconnect the load from a generator, it becomes much easier to spin it (less energy is delivered).

Dear,

The as per energy conservation law, all the mechanical energy given to generator must be converted in other form of energy. If load of a generator is cut off while running, it will try to over speed as electrical load is now almost zero. But protection system will cut the supply of steam / water to the turbine. And that stem will be thrown to atmosphere until the input of boiler is reduced (again law of conservation).

Dear Mr.questionsquestions

The Energy flow is on account of a proper circuit and generator converts Mechanical Energy to Electrical Energy (losses like friction, windage, winding heating are ignored) and flows through the wire/cable.

If the wire/cable is open the current flow stops and hence the Mechanical Energy demand will come down and keep the generator revolving with minimum energy input.

If Earthing is proper, any short circuit - the Protection Relay system will trip, and protect the system.

DHAYANANDHAN.S