Equation relating rotational velocity and output electrical power

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SUMMARY

The discussion centers on the relationship between angular velocity and electrical power output in alternators and DC generators. Key equations include Faraday's Law and the formula for induced voltage in a rotating loop, expressed as V = (ωNA₀B₀)/√2. The efficiency of alternators varies significantly, with automotive alternators averaging 50-60% efficiency, while utility-scale alternators can achieve up to 99% efficiency. Understanding these principles is crucial for optimizing electrical power generation from mechanical systems.

PREREQUISITES
  • Understanding of Faraday's Law of Electromagnetic Induction
  • Knowledge of angular velocity and its relation to electrical power
  • Familiarity with the concept of efficiency in electrical machines
  • Basic principles of electromagnetic fields and their applications
NEXT STEPS
  • Study the derivation and applications of Faraday's Law in electrical engineering
  • Research the efficiency metrics of different types of alternators
  • Explore the mathematical modeling of DC generators and their performance characteristics
  • Investigate the impact of load variations on alternator efficiency
USEFUL FOR

Electrical engineers, power generation specialists, and students studying electromagnetic theory will benefit from this discussion, particularly those focused on optimizing the performance of alternators and DC generators.

Charles123
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What is the equation that relates the angular velocity of an alternator rotor with its output electrical power, voltage and frequency (not necessarily just one equation) .
And for a DC generator?
I know that when you calculate the power generated by a turbine you multiply its efficiency of conversion and the theoretical power that you can extract from a flow with that swept area by the turbine. I assume that in that efficiency is the factor of conversion to electrical power. How does that work?
regards
 
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Start with Maxwell's equation in differential form
curl\space E = - dB/dt
Integrate to get Faraday's Law:
\oint E\space d\ell= - \frac{d}{dt}\int_{A}^{}B\cdot n \space dA
The induced voltage in an N-turn loop around the perimeter of an area A is equal to minus the time derivative of the perpendicular magnetic field integrated over the area inside the loop. Either the magnetic field or the area can be a function of time. If an N-turn loop of area A(t) = Aosin(ωt) rotates in a dc magnetic field B0 with angular frequency ω, then the rms output voltage is
V= \frac{\omega NA_0 B_0}{\surd 2}

Bob S
 
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That's a kinda general question...
like asking what make a centrifugal pump work..

Here's a fairly scholarly article on automobile alternators and where they are going
www.rle.mit.edu/per/JournalPapers/JPtpemay04p618.pdf

and the Wikipedia page really is pretty good
http://en.wikipedia.org/wiki/Alternator

Alternators in cars have widely varying efficiency at various speeds and loads. Take 50-60% as ballpark.
Utility central station alternators can be, as you doubtless know, 99% efficient.
 

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