# How much electricity can a generator generate before it wears out?

1. ### Psinter

159
I was wondering out of boredom, how much would a generator last generating electricity if I keep it running for forever.

Assuming I have fuel for forever and I start a generator, how much would it last before it stops generating electricity?

Like, does the copper wires wear out and stop generating electricity at some point in time? How much electricity would it have generated until the copper runs out? (if it runs out at all)

I know I cannot have fuel for forever, but idk I sort of wonder what would be its maximum potential before it wears out (if it wears out).

### Staff: Mentor

What kind of things do you think are on a generator's periodic maintenance (PM) schedule?

3. ### carlgrace

555
It depends almost entirely on the design of the generator. Also, the copper will likely never "run out" unless you are driving big DC currents through it in which case you have to look out for electromigration which can create voids in the metal's crystal structure.

4. ### sophiecentaur

13,392
There is no limit if you can replace the bearings and brushes, assuming that any of the insulation and supporting material doesn't break down due to overheating or vibration. I'm assuming that, in your scenario, you're allowed to stop for periodic maintenance.

5. ### Psinter

159
The word "maintenance" triggers in my head: oiling or greasing the moving parts of the engine, checking for problems on moving parts because of heat/friction and fix them if deemed neccesary before they become a bigger deal, and new oil. But I can't find any reason to touch the copper wires of the coil, so they are not included in the maintenance. That's my guess.

I see. Thanks for your answers.

@sophiecentaur
LOL! Your signature. "It's turtles all the way down!" :rofl:

6. ### sophiecentaur

13,392
Did you get the reference?

This thread puts me in mind of the "Trigger's Broom" idea - same broom but six new heads and four new shafts.

7. ### SteamKing

8,607
Staff Emeritus
Were you afraid of running out of electrons if the generator runs too long?

4,507

### Staff: Mentor

I have a notion that a permanent field magnet will eventually weaken, not through being "used up", but from heat and vibration and an opposing field knocking it around. So if your generator were based on a set of permanent magnets, I think to keep it as new these may need to be replaced (or re-set) after some tens of thousands of hours of bumping that dis-aligns some of the domains.
Thank you. I'll just add that one to my emoticon album!

10. ### Psinter

159
Sort of
Not exactly afraid, it was more like curious. But up to a certain point, yes.
Whoa, neat and amazing. I live close to a river, but I don't think it has enough flow to put a generator there.

I see, that's a lot of time. Probably more than my lifespan.

Btw, aren't all electricity generators based on permanent magnets? I may be wrong, but I think a permanent magnet is a must. Like I can't think of any that doesn't have those.

Last edited: Mar 20, 2013
11. ### SteamKing

8,607
Staff Emeritus
AC or DC generators can be self-excited, which means that a separate current is used to create an electro-magnetic field. Such devices do not use permanent magnets.

### Staff: Mentor

You anticipate a very short life span?
An electromagnet can be constructed to generate a stronger field than we can get from a permanent magnet. (At least, that used to be true, with newer materials the situation may have changed.) If you want to be able to vary the strength of the field, it's far easier to do with an electromagnet.

13. ### gerbi

162
If you will retrofit insulation system, worn mechanical elements etc. it will work as long as copper won't turn into something else - but this is a question rather to a chemist or physicist (you know, chemical elements stability, decay time and stuff).

There are two main methods to create excitation magnetic field in machine: permeant magnets and electromagnets (it's a coil, either supplied from outside source or in a self-excited verison). Permeant magnets are used in small devices, in bigger ones electromagnets are used.

14. ### d3mm

139
QFT says it's fields not turtles :-)

15. ### Jobrag

518
It will run till it runs out of smoke, all electrical devices need smoke to work. When you see the smoke coming out of an electrical device you know that it wont work again.

16. ### jim hardy

4,507
In US household wiring the wire with the smoke in it is black.

17. ### sophiecentaur

13,392
It's a sort of fail safe colouring system (I'm not entirely joking). If you find a brown wire then it could be live. i.e. a live (brown) one or a blue one that has gone brown in the heat. If you find a blue one then you know it must be the neutral. And the Green / Yellow stripe would still appear stripy, even when burned. Cunning eh?

18. ### anorlunda

438
The electric generators at Niagara Falls served continuously for 111 years (if my memory is correct) with little more than a few drops of oil each year. They were retired, not because they wore out, but rather because modern turbine/generators are more efficient, and because there was not much market for the 25 hertz power that the original generators generated.

The answer is that electric generators don't wear out; at least they don't wear more than any other machine with moving parts.

19. ### sophiecentaur

13,392
That's a proper little gem of information - cheers. Flickering light bulbs or whaaaat?

20. ### jim hardy

4,507
I visited that site in early 1970's. Indeed the lights in old buildings with 25 (or was it 20?) hz power had visible flicker.

Hydro power is incredibly cheap.
At that time my father-in-law's plant nearby bought electricity delivered to their transformer for 1.8 mils per kwh.
Even then that was less than our nuclear fuel cost.
It's less than $\frac{1}{50}$th of my residential cost today.
But - regulation came along.
NY State took over and put an end to the economic benefit of proximity to hydro.
Lots of industry around Niagara Falls shut down. Father-in-law's plant got moved to Brazil.

old jim

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