Motor and alternator in same shaft

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Discussion Overview

The discussion revolves around the feasibility and implications of having a motor and an alternator on the same shaft, specifically focusing on the operational parameters of a 12V motor and a 220V alternator. The scope includes theoretical considerations of energy conservation, power output, and practical applications.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the meaning of running both the motor and alternator on the same shaft, suggesting that directly connecting a 220V output to a 12V motor would damage it, indicating the need for a transformer.
  • Another participant notes that the motor will consume more power than the generator can output, emphasizing that this setup cannot function as a perpetual motion machine and referencing similar devices used in power supplies.
  • A claim is made that a motor consuming 12V and 2A would not produce 300 watts from the alternator, estimating a maximum output of 24 watts due to losses.
  • It is stated that the maximum power output of a generator powered by the motor can only equal the mechanical energy supplied to it, reiterating the principle of conservation of energy.

Areas of Agreement / Disagreement

Participants express disagreement regarding the potential power output of the alternator and the implications of energy conservation in this setup. There is no consensus on the practicality or efficiency of using a motor and alternator in this manner.

Contextual Notes

Participants highlight limitations related to assumptions about efficiency, power consumption, and the definitions of energy output in the context of the motor and alternator configuration.

vadali
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Sir,
Should we make both Motor and Alternator on same shaft?
the Motor will run at 12V and it should not consume >2 Amps and tha same time Alternator should produce 220 V 300watts.

Please reply
 
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not sure what you mean by running them on the same shaft... but if you mean to have the alternator power your motor, hooking up 220V directly to a 12V motor will destroy it... you'd need a transformer to drop the voltage and be able to provide enough current.
 
The motor will consume more power than the generator outputs, so it's not a perpetual motion machine. Similar devices are used in some power supplies, relying on the momentum of the motor to provide "cleaner" output to mask variances in the input power. Large ones were used on old mainframes:

http://smud.apogee.net/comsuite/content/ces/?utilid=smud&id=1586

There are some audiophile power conditioners still being made using motor + altenator (called power regenators), but I don't know if this is more of a gimmick method than a pratical one.
 
Last edited by a moderator:
A motor consuming 12 volts and 2 amps would NOT produce 300 watts from an alternator attached to it. It would at best produce 24 watts, and realistically produce less thanks to losses.
 
Ultimately, it comes down to conservation of energy, as drakkith said. Power is Voltage times current, so a motor running on 12V 2A consumes 24W of power. A generator powered by that motor (and that motor alone) can produce at a maximum (100% efficiency) only what is supplied to it in the form of mechanical energy IE: 24J/s, or 24W.
 

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