motor generator

[epilot]

hi friends,
sorry if my question is a kind of stupid questions :lol:
but why a DC motor could not to Provide its required power by another motor conected to it?! what i mean? well suppose 2 motor are connected togather by (shaft to shaft) you just turn the shaft and connect wires of one motor to other motor, one motor acts as a generator and the other motor gets the voltage and spins itself and the other motor(generator)

i know if we could to generate any power from that system that power would be very low but what do you think about it in theory? :wink:

 

[Nigel Goodwin]

hi friends,
sorry if my question is a kind of stupid questions :lol:
but why a DC motor could not to Provide its required power by another motor conected to it?! what i mean? well suppose 2 motor are connected togather by (shaft to shaft) you just turn the shaft and connect wires of one motor to other motor, one motor acts as a generator and the other motor gets the voltage and spins itself and the other motor(generator)

i know if we could to generate any power from that system that power would be very low but what do you think about it in theory? :wink:

It's completely stupid in theory, but is the basis of MANY bogus pertetual motion designs.

Like any such device it needs to work at greater than 100% efficiency, which is impossible (as is 100% efficiency).

If you need it making clearer?, imagine both the motor and generator are 90% efficient - and they won't be that high!.

OK, 90% efficient - so the motor turns ten times, and the generator provides enough power to turn it nine times. So the motor turns nine times, producing enough power to turn it 8.1 times and so on.....

You get the picture? - after a fairly smaller number of revolutions it will stop, and that's AFTER inputing the initial power to give ten turns!, AND without trying to draw anything from it!.

Silly idea! - go the back of the class and wear a pointed hat :lol:

 

[epilot]

It's completely stupid in theory, but is the basis of MANY bogus pertetual motion designs.

Like any such device it needs to work at greater than 100% efficiency, which is impossible (as is 100% efficiency).

If you need it making clearer?, imagine both the motor and generator are 90% efficient - and they won't be that high!.

OK, 90% efficient - so the motor turns ten times, and the generator provides enough power to turn it nine times. So the motor turns nine times, producing enough power to turn it 8.1 times and so on.....

You get the picture? - after a fairly smaller number of revolutions it will stop, and that's AFTER inputing the initial power to give ten turns!, AND without trying to draw anything from it!.

Silly idea! - go the back of the class and wear a pointed hat :lol:[/quote]

o sorry i forgot to talk about a "flywheel"...

https://www.zpenergy.com/modules.php?name=News&file=article&sid=1435

do you want me to wear 2 pointed hat because i wear one everyday
:lol:

 

[Nigel Goodwin]

o sorry i forgot to talk about a "flywheel"...

https://www.zpenergy.com/modules.php?name=News&file=article&sid=1435

Unless it's a 'magic' flywheel it won't help!.

do you want me to wear 2 pointed hat because i wear one everyday
:lol:

Does it have a big 'D' on the front? :lol:

 

[epilot]

Unless it's a 'magic' flywheel it won't help!.

did you read that link?

Does it have a big 'D' on the front? :lol:

you know that i am not an english man and my english is so broken
so what a "D" means really?
does it means a student of Doctoral? :lol:


i am agree about motor efficiency completely
but that stupid question was because of seeing that link!
perhaps these perpetual motors are a kind of magics or bogus such as you said!

 

[Nigel Goodwin]

Does it have a big 'D' on the front? :lol:

you know that i am not an english man and my english is so broken
so what a "D" means really?
does it means a student of Doctoral? :lol:
[/quote]

If you had your location filled in we might know where you were?, and could make an educated guess about your first language!. It's IMPORTANT to have your location entered for many questions.

The 'D' stands for 'Dunce', and the tall pointed hat with a D on was a 'Dunces hat' - historically stupid children in British schools were supposed to be made to stand in the corner wearing one :lol:

If it ever happened, it was well before my time 8)

 

[epilot]

Does it have a big 'D' on the front? :lol:

you know that i am not an english man and my english is so broken
so what a "D" means really?
does it means a student of Doctoral? :lol:

If you had your location filled in we might know where you were?, and could make an educated guess about your first language!. It's IMPORTANT to have your location entered for many questions.

The 'D' stands for 'Dunce', and the tall pointed hat with a D on was a 'Dunces hat' - historically stupid children in British schools were supposed to be made to stand in the corner wearing one :lol:

If it ever happened, it was well before my time 8)[/quote]

ohhh thanks Nigel for your kind words :lol: :lol:

so it is so good that i dont live at UK :lol:

ok i'll put my location for respect you :wink:

 

[Styx]

Ahh good Old Dunce hats, my nan says she was made to stand in the corner, but she might of said that to scare me into doing my homework

hi friends,
sorry if my question is a kind of stupid questions :lol:
but why a DC motor could not to Provide its required power by another motor conected to it?! what i mean? well suppose 2 motor are connected togather by (shaft to shaft) you just turn the shaft and connect wires of one motor to other motor, one motor acts as a generator and the other motor gets the voltage and spins itself and the other motor(generator)

i know if we could to generate any power from that system that power would be very low but what do you think about it in theory? :wink:

Ahh the good old propetial motion machine...
Well I will fill in the blanks that Nigel left out with his little fun&games

Lets take a DC brushed machine (although the same is true for all machines)

NOw you hook this machine up to a battery and let it spin, even with no load attached current is drawn. Why? because there is a load, the rotor and this load MUST be overcome, thus power is used to spin it

There is also power lossed in the leads and windings (as copper/resistive losses) as well as resistive losses in the carbon brushes.

There then is frictional losses in the actual brush contacts as well as the bearings.


Now lets say we put a bit of load onto the motor shaft (say a brake pad). Say we have it spinning at a speed, the Mechanical power at the shaft will be equal to P=Tw in Watts (T=torque and w is speed in rad/s)

IF the machine was 100% efficient then the electrical power going in would be the same as the mechanical power coming out

ie

I*V = T*w


BUT as I have stated power is lossed within the machine.
So to get X watts out, you must put X+Y watts in.


Eqaully IF you were to run a machine as a generator for a given electrical power out you would need extra mechanical power in to overcome the losses

Thus as you can see it is impossible

 

[ljcox]

ohhh thanks Nigel for your kind words :lol: :lol:

so it is so good that i dont live at UK

ok i'll put my location for respect you

Nigel's humour may be a bit blunt at times, but he does spend a lot of his time helping people.

 

[akg]

there is an experiment to determine the efficiency of dc motors by this method. if i remeber correct , it is hopkinson's experiment