You then turn off half of the motors. The generator is still spinning at the same speed producing the same amount of energy because it does not know the motors are turned off and you need less energy. For that split second the wires are conducting far more energy than what you need. What happens to that excess energy? Where does it go?
You have to think of it like this: the generator is "pushing" electricity into the grid.
Imagine you are pushing someone along on a bicycle, but they have the brakes on. You are pushing really hard, but they are only moving slowly. Suddenly they let off the brakes. You are still pushing really hard, but the resistance has suddenly dropped. You are pushing much harder than you really need to. What happens to all your excess energy?
I thought we agreed if the generator is spinning faster voltage would increase.
Yep.And if spinning at twice the speed there were by 4 X the kinetic energy.
If the turbine spins at twice the speed, the turbine will have 4x the kinetic energy, yes.My question is where is all of that extra energy going?
The energy is not going anywhere. A faster spinning turbine has more kinetic energy, just like a fully charged battery has more chemical energy in it. Energy doesn't have to go places, you can just have a system with lots of gravitational potential energy (fully filled dam), lots of chemical potential energy (charged batteries, a pile of coal), or lots of kinetic energy (a rapidly spinning heavy thing), and that's just fine. The energy can stay where it is, it's not a flow (like power) and so it doesn't have to flow, let alone flow to any particular place.
I think you're confusing energy and power? Energy is measured in Joules, and power is measured in Joules per second (also known as Watts). There's a recent EEVBlog video that goes into some detail on this, you really need to have this concept down before you can discuss subtle things like an imbalance in the power going into/out of a turbine leading to a change in the kinetic energy of the turbine (and that being the end of the story and just fine) -- just like an imbalance in the water flow going into/out of a bucket leading to a change in the quantity of water in the bucket with no need to "explain" where all that "extra water" "goes".
Not sure we agree on the definitions or use of words in the same way.
Are you saying a short does not cause or result in an an over current event?
A short circuit is one where electrons/current flow through an unintended path with very no or very little resistance.
A short circuit is when the current takes a shorter path than it is intended to take. Hence "short" circuit. A short may be high resistance or low resistance, but it is true that a low resistance is commonly assumed in casual speech.
An over current situation is again what the words describe. It is a situation when the current is over what it is intended to be, or over the maximum designed for or allowed for. Hence "over" current. Usually an over current situation will be protected against by tripping a fuse or circuit breaker.QuoteI was taught electrocution is what happens when a person becomes a conductor either intentionally or accidentally accompanied with an external flow of electrons/current through the body.
Electrocution is to be killed by electricity passing through the body. If you don't die it is not electrocution.QuoteNot sure what the cherry picker was made out of. I'm surprised if you understand electricity why you don't understand why the two guys in the cherry picker were being electrocuted.
If the cherry picker was made out of an insulator like GRP, then no current would flow at all and the people riding on it would be safe. This is the case with any cherry pickers that might be used near overhead wires.
If the cherry picker was made out of steel then its resistance would be very low and as soon as it contacted the wires it would cause a short circuit and an over current situation (see above) and the breaker would trip, cutting power to the wires. In the unlikely event that the breaker didn't trip, then the low resistance of the steel would prevent any differential voltage being high enough to cause harm. (Unless the unfortunate person was between the high voltage wires and the cherry picker. In that case they would not only be electrocuted, they would be instantly incinerated.)QuoteIf a live wire falls on the ground firemen are taught to keep both feet in contact with the ground and shuffle away from the live wire. If they take a stride the resistance of the ground can be high enough current will flow up one leg and down the other electrocuting the fireman.
Just a quick footnote: it is quite unlikely a human can be electrocuted in this way, because the electrical path up one leg and down the other does not pass through a human's heart. In addition to which, the fireman is probably wearing heavy insulated boots. It is sensible to take the proper precautions and avoid unnecessary risks, but the actual risk is not that great.
Not sure what the cherry picker was made out of. I'm surprised if you understand electricity why you don't understand why the two guys in the cherry picker were being electrocuted. This is something firemen are taught with live wires. If a live wire falls on the ground firemen are taught to keep both feet in contact with the ground and shuffle away from the live wire. If they take a stride the resistance of the ground can be high enough current will flow up one leg and down the other electrocuting the fireman. I remember hearing of three police horses being killed in Florida because of a live wire in a field. The resistance of the ground between the legs of the horses was enough that the current flowed through the horses killing them.
This is what I was taught. Not say I'm right, but then again I've been looking up the definition of the words to make sure I'm using them as properly.
I do want to thank you for questioning me. It's required me to do a fair amount of researcher to confirm what I saying is correct.
I thought we agreed if the generator is spinning faster voltage would increase.
Yep.And if spinning at twice the speed there were by 4 X the kinetic energy.
If the turbine spins at twice the speed, the turbine will have 4x the kinetic energy, yes.My question is where is all of that extra energy going?
The energy is not going anywhere. A faster spinning turbine has more kinetic energy, just like a fully charged battery has more chemical energy in it. Energy doesn't have to go places, you can just have a system with lots of gravitational potential energy (fully filled dam), lots of chemical potential energy (charged batteries, a pile of coal), or lots of kinetic energy (a rapidly spinning heavy thing), and that's just fine. The energy can stay where it is, it's not a flow (like power) and so it doesn't have to flow, let alone flow to any particular place.
I think you're confusing energy and power? Energy is measured in Joules, and power is measured in Joules per second (also known as Watts). There's a recent EEVBlog video that goes into some detail on this, you really need to have this concept down before you can discuss subtle things like an imbalance in the power going into/out of a turbine leading to a change in the kinetic energy of the turbine (and that being the end of the story and just fine) -- just like an imbalance in the water flow going into/out of a bucket leading to a change in the quantity of water in the bucket with no need to "explain" where all that "extra water" "goes".
I will disagree with you. The moment the load is removed from the circuit the generator "doesn't know" and will still be sending the same amount of energy/watts in the wires. Similar concept in plumbing with pipes hammering. The hammering is how the excess energy is being dissipated. What's the equivalent to pipe hammering with the generator.
Can you give me an example of a short circuit with high resistance?
I will disagree with you. The moment the load is removed from the circuit the generator "doesn't know" and will still be sending the same amount of energy/watts in the wires.
Similar concept in plumbing with pipes hammering. The hammering is how the excess energy is being dissipated. What's the equivalent to pipe hammering with the generator.
Exactly At the moment the brakes are let of the amount of energy you are pushing with has to go somewhere so you fall forward and hit the ground. That extra KE you aren't using to push is instantaneously converted to PE (since you have no resistance) than as you begin to fall it's converted to PE (as you are falling) then it's converted to heat and sound as you hit the ground.
*More specifically, synchronous machines do. Shorting slats are simply shorted turns on the armature, which act to slow any change in its magnetic field (which is an electromagnet, so the field is supposed to be static anyway). Note: I haven't studied modern generators per se -- their design may vary. Anyway, even if this isn't the exact solution used, the same effect is required, however it's achieved.
Can you give me an example of a short circuit with high resistance?
Let’s say I have a circuit only capable of 1uA output current. If I place a 1MOhm resistor on it’s output, it’s essentially a short circuit.
Let’s say I have a circuit only capable of 1uA output current. If I place a 1MOhm resistor on it’s output, it’s essentially a short circuit.
How is that a short circuit? Can you provide a reference source which describes the scenario you described as a short circuit?
In circuit analysis, a short circuit is defined as a connection between two nodes that forces them to be at the same voltage. In an 'ideal' short circuit, this means there is no resistance and thus no voltage drop across the connection.
I've had the opportunity to study a few GE power house alternators in a repair shop and before installation. Very interesting stuff.
[snip]
Let's imagine the 1 µA flowing through the 1 meg-ohm resistor. By Ohm's law, the voltage difference across the resistor will be 1 V. Now in practical terms, if the two nodes are only one volt apart, they are effectively "at the same voltage". Especially since a circuit capable of only 1 µA output is likely to produce thousands of volts in the normal mode of operation. Compare 1 volt to thousands of volts and the two nodes may as well be at the same voltage. So it's a short circuit.
Could you please read a textbook?
Could you please read a textbook?
OK
Where do you think I made an error?
Let's imagine the 1 µA flowing through the 1 meg-ohm resistor. By Ohm's law, the voltage difference across the resistor will be 1 V. Now in practical terms, if the two nodes are only one volt apart, they are effectively "at the same voltage".
Especially since a circuit capable of only 1 µA output is likely to produce thousands of volts in the normal mode of operation.
Compare 1 volt to thousands of volts and the two nodes may as well be at the same voltage. So it's a short circuit.
OK, I guess context is important.
We could imagine an electrostatic machine with an output current of 1 µA that in normal operation would charge up an output terminal to a high voltage. If we connected this output terminal to ground with a 1 meg resistor, then the output wouldn't generate any voltage at all. In that context it would effectively be shorted.
A short is simply zero ohms -- to imply otherwise, whether in context or not, is simply not good usage!
Tim
A short is simply zero ohms -- to imply otherwise, whether in context or not, is simply not good usage!
Tim
So, you’re saying if I have a 1uA current source with a, say, 10V compliance voltage and I place a 10, 100 or even 1kOhm resistance across it, it wouldn’t be considered shorted? Who knew!
Interesting in how in over a hundred years of using electricity we still can't agree on the use of words and terms such as short-circuit.
You know, thinking about this question a bit more, there’s two critical things I think @DougSpindler fails to grasp: A generator can run freely without any load and power isn’t what he thinks it is.
Think about this, I have a propane based whole home generator with automatic switchover. When it starts up, the engine is spinning the generator windings just fine even though they aren’t connected to an electrical load. At this point the generator is producing 120VAC@60Hz and putting out 0A. Suddenly, a solenoid throws an A/B switch and my entire house is connected as the load. Now, you can hear the engine connected to the generator briefly whine and slow down a bit. At this point it might be producing 110VAC@58Hz and putting out 30A. Within a second or so, the control loop inside the unit increases gas flow to the engine, to compensate for this newly added load. Now we’re back to 120VAC@60Hz. After a few minutes, say my Air Con kicks off, decreasing the load on the generator, so now the voltage jumps to 125VAC@61Hz until the control loop slows the engine.
Now, I know what you’re thinking, at the end there the “power” jumped up, right? Well, no. The voltage may have gone up five volts, however the current would have gone down an equivalent amount, keeping the total power draw the same.
So, while voltage may fluctuate as I add and shed loads to my generator, the overall wattage used will stay the same (since an appliance will use less current at a higher voltage and vice versa).
Keep in mind this is different for the typical power distribution network, as there are so many generators spread out over such a large area that as loads are added and shed it’s basically imperceptible to the home user.