- #1
mtanti
- 172
- 0
Does anyone know of an equation which relates RPM with power in a generator? It has to be for a general generator! 
Generator Equation: RPM & Power Relationship
- Thread starter mtanti
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Discussion Overview
The discussion revolves around the relationship between RPM (revolutions per minute) and power in generators, focusing on general equations applicable to various types of generators. Participants explore theoretical aspects, including the implications of RPM on power output and frequency in alternating current systems.
Discussion Character
- Exploratory
- Technical explanation
- Mathematical reasoning
Main Points Raised
- One participant inquires about a general equation relating RPM to power in generators.
- Another participant suggests using a sinusoidal voltage function and relates angular frequency to RPM, noting that current and impedance are also necessary for a complete analysis.
- A different participant explains that in alternating current systems, the RPM of the generator affects the output frequency, specifically mentioning the standard frequency of 60Hz in the U.S. and its relationship to load changes.
- Another contribution presents a general equation for output power, indicating that it is equal to input power minus losses, and relates it to RPM and torque without delving into more complex factors like reaction torque or inertia.
Areas of Agreement / Disagreement
Participants express various viewpoints and approaches to the relationship between RPM and power, with no consensus reached on a singular equation or model. The discussion remains open with multiple competing ideas presented.
Contextual Notes
Some assumptions regarding the operational conditions of generators and the definitions of terms like torque and losses are not fully explored, which may affect the applicability of the proposed equations.
- #2
toxique
- 19
- 0
I am not sure (im still a newbe 
), but let's work in senoidal regime:
Voltage v(t) = V . sin(wt+p)
w (omega) is in radians, so you could make w an equivalent to RPM:
1 RPM = 1 radian = 2*PI
Of curse, you will also need current and impedances for a deep analysis, but you can get the idea (P = (V^2)/Z)
I hope this is OK, sorry everyone if this is screwed up.
), but let's work in senoidal regime:Voltage v(t) = V . sin(wt+p)
w (omega) is in radians, so you could make w an equivalent to RPM:
1 RPM = 1 radian = 2*PI
Of curse, you will also need current and impedances for a deep analysis, but you can get the idea (P = (V^2)/Z)
I hope this is OK, sorry everyone if this is screwed up.
- #3
dlgoff
Science Advisor
Gold Member
- 4,458
- 3,265
For alternating current (A.C.), the RPM of the generator determines the frequency of its output. In the U.S., power companies try to keep the frequency at 60Hz. When the load on the systems increases, the frequency tends to lower, so more power (steam flow through the turbin) is needed. The opposite happens when the load decreases.
Regards
Don
Regards
Don
- #4
phantom_photon
- 19
- 0
Well,
output power = input power - losses = wT - losses = (2*pi/60)*RPM*T -losses.
That's the most general equation I can think of without getting into reaction torque, inertia, etc.
output power = input power - losses = wT - losses = (2*pi/60)*RPM*T -losses.
That's the most general equation I can think of without getting into reaction torque, inertia, etc.