If we use a high speed motor and reduce its rpm hence gaining more power from it, and then use that to run a generator which generates about double the power being consumed by the motor at that speed will the system be self sustaining or will it not work.
-
\$\begingroup\$ Energy can niether be created nor destroyed bur can be converted from one form to the other! \$\endgroup\$– JasserApr 2, 2016 at 8:26
-
\$\begingroup\$ Not an answer but an anecdote: In 1775, the Royal Academy of Sciences in Paris made the statement that the Academy "will no longer accept or deal with proposals concerning perpetual motion." en.wikipedia.org/wiki/… So scienctists won't even think about ideas such as yours for over 200 years now. Whenever you come across such an idea you shouldn't ask "Will it work?", but "Why is it not going to work?" \$\endgroup\$– ChristianApr 2, 2016 at 9:19
-
\$\begingroup\$ US Patent Office won't accept perpetual motion submissions either. \$\endgroup\$– TransistorApr 2, 2016 at 9:38
-
\$\begingroup\$ If you are not happy with the answers below then add some calculations using data from motor and generator datasheets. See how far you get. \$\endgroup\$– TransistorApr 2, 2016 at 9:43
-
3\$\begingroup\$ I'm voting to close this question as off-topic because it contains assertions that are plainly wrong. \$\endgroup\$– Andy akaApr 2, 2016 at 9:46
3 Answers
No generator can generate even the same mechanical power applied to it. So of course it cannot double the received mechanical power. So no, it won't be self sustaining.
-
\$\begingroup\$ We are using a high speed motor whose rpm we decrease using a gear ratio of 2:1, hence we are doubling the power of the motor which is still consuming the same amount of current, this doubled mechanical power we apply to a generator which should make less than the double of the mechanical power given to it, hence will it not be sufficient to run the motor? \$\endgroup\$– hispeedApr 2, 2016 at 6:15
-
\$\begingroup\$ When you reduce the speed with a reductor you increment the torque, not the power. The power of a motor is T.w, where T is torque and w is rotational speed. If you used an ideal reductor you would have doubled the torque but halved the speed so power remains the same. In the real world no reductor is ideal so when you use a reductor you actually LOSE some of the mechanical power available at the axis of the motor. \$\endgroup\$ Apr 2, 2016 at 6:19
-
\$\begingroup\$ mm. See we have a motor which can run at 7000 rpm. But we reduce its rpm to 3000rpm using your formula the power will remain the same but the generator can function at 2000 rpm so will this not work? \$\endgroup\$– hispeedApr 2, 2016 at 6:21
-
\$\begingroup\$ hispeed, this is quite elementary physics. I advice to you to go and learn a bit or, if you want, mount the setup and check for yourself. Good luck. \$\endgroup\$ Apr 2, 2016 at 6:24
If we use a high speed motor and reduce its rpm hence gaining more power from it.
No, you can't gain more power from it. You will get higher torque and reduced angular speed. Power = Torque X angular speed, which remains constant (ideally). Practically, gears aren't 100 % efficient and you will lose some power. Also, there will be some other frictional losses in motor and generator.
Keeping everything aside - You can't just create energy out of no where. If it would have been the case, the energy crisis would have long been solved.
-
\$\begingroup\$ mm. See we have a motor which can run at 7000 rpm. But we reduce its rpm to 3000rpm using your formula the power will remain the same but the generator can function at 2000 rpm so will this not work? \$\endgroup\$– hispeedApr 2, 2016 at 6:20
-
\$\begingroup\$ No, whatever you do, whole setup will not give you more output power than input power. You can try harvesting power from other sources though, for ex - if you modify your generator to be run using wind or by a flowing stream of water, then you can generate power from there. If your method would have worked, companies would have been selling fans which do not need mains supply at all, but we don't see such fans in the market. Do we? :) \$\endgroup\$ Apr 2, 2016 at 7:43
This is how it works.
The following is not a "proof" - it is a statement of how nature is known to work.
There is lots on the web on this.
You can easily find much that explains things like "conservation of energy" and the laws of thermodynamics.
Terms like "Perpetual motion machine", "Perpetuum mobile", "Over Unity", free energy and similar are used to describe devices of this type. None work. Ever.Many of us (certainly including me :-)) have wondered why this should not be possible as we began to learn about electrical things. All of us who wondered in time found out that it was not possible, and why.
Over 50 years ago (!) I drew pictures of motors and transformers and power sources and loads and 'invented' a system which seemed like it may make free energy in a manner similar to yours. I asked my teacher why it would not work (as it was fairly clear that if it was possible people would have done it long before then. He could not explain why not - but it helped put me on the path to becoming an electrical engineer :-).Doing this would 'break the laws of Physics.
For a motor mechanical energy out <= electrical energy in.
For an alternator or generator electrical energy out <= mechanical energy in.
In both the above case some energy is "lost" in mechanical resistance (air drag, bearings, ... and electrical losses (resistive heating in wires, magnetic ddy current losses, ...). Some energy is always lost when energy is converted from one form to another. The "lost" energy is usually converted to heat either directly or via some other intermediate step or steps.
Make or sketch or imagine a motor-generator loop and apply the concepts mentioned above and you will see that it cannot self sustain.
Many people try to make 'free' energy in this way or by similar means.
NONE succeed.
Not ever.Some people (on the internet or elsewhere) CLAIM to provide systems or designs that do this.
NONE have ever worked.
ALL such people are either liars or are fooling themselves by bad measurement methods.