Equation relating rotational velocity and output electrical power

AI Thread Summary
The discussion focuses on the relationship between angular velocity, output electrical power, voltage, and frequency in alternators and DC generators. It begins with Maxwell's equation, leading to Faraday's Law, which describes how induced voltage in a loop is related to the changing magnetic field. For a rotating loop in a magnetic field, the root mean square (rms) output voltage can be calculated using the formula V = (ωNA₀B₀)/√2. The efficiency of alternators varies significantly, with automotive models averaging around 50-60% efficiency, while utility-scale alternators can reach up to 99% efficiency. Understanding these principles is crucial for optimizing electrical power generation from mechanical sources.
Charles123
Messages
131
Reaction score
0
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
 
Engineering news on Phys.org
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
 
Last edited:
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.
 
Hi all I have some confusion about piezoelectrical sensors combination. If i have three acoustic piezoelectrical sensors (with same receive sensitivity in dB ref V/1uPa) placed at specific distance, these sensors receive acoustic signal from a sound source placed at far field distance (Plane Wave) and from broadside. I receive output of these sensors through individual preamplifiers, add them through hardware like summer circuit adder or in software after digitization and in this way got an...
I have recently moved into a new (rather ancient) house and had a few trips of my Residual Current breaker. I dug out my old Socket tester which tell me the three pins are correct. But then the Red warning light tells me my socket(s) fail the loop test. I never had this before but my last house had an overhead supply with no Earth from the company. The tester said "get this checked" and the man said the (high but not ridiculous) earth resistance was acceptable. I stuck a new copper earth...
I am not an electrical engineering student, but a lowly apprentice electrician. I learn both on the job and also take classes for my apprenticeship. I recently wired my first transformer and I understand that the neutral and ground are bonded together in the transformer or in the service. What I don't understand is, if the neutral is a current carrying conductor, which is then bonded to the ground conductor, why does current only flow back to its source and not on the ground path...
Back
Top