# I Power output of a theoretical generator

#### topcatthomas

so, assuming that you know all of the aspects of your theoretical generator, apart from the voltage and current, how would you work it out. I know that it is possible, but i can't find anything that I understand, or is even valid online. There should be some equations i can use to work it all out, so what are those?
Thanks.
please could you use word equations as I may not know what the symbols mean.

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#### OmCheeto

Gold Member
The power output of a generator, in a "wordy equation" would simply be:
Power equals Voltage times Amperes.

Or are you asking what the maximum power output would be?

#### topcatthomas

The power output of a generator, in a "wordy equation" would simply be:
Power equals Voltage times Amperes.

Or are you asking what the maximum power output would be?
Yes, but how do you work out the voltage and current? I can't measure it if it isn't real.

#### Dale

Mentor
Yes, but how do you work out the voltage and current? I can't measure it if it isn't real.
I don’t understand, why isn’t voltage and current real.

#### OmCheeto

Gold Member
Yes, but how do you work out the voltage and current? ....
Voltage is equal to the rate of change of a magnetic field. Typically in the presence of a conductor, from what I hear.

#### berkeman

Mentor
so, assuming that you know all of the aspects of your theoretical generator, apart from the voltage and current, how would you work it out. I know that it is possible, but i can't find anything that I understand, or is even valid online. There should be some equations i can use to work it all out, so what are those?
Thanks.
please could you use word equations as I may not know what the symbols mean.
Welcome to the PF.

Can you say what your application is? It's a bit hard to help you without knowing more. Especially if you want the description without any equations -- that is especially challenging, but we will try out best if you can tell us more about what you are trying to do.

#### anorlunda

Mentor
Even without your background, I can tell you that the current depends on the load, not the generator. Zero load zero current.

#### berkeman

Mentor
please could you use word equations as I may not know what the symbols mean.
Also, are you comfortable with basic equations like Ohm's law: V = I * R and the definition of electrical power, P = V * I ? That would be a big help if you are okay with those basic equations.

#### LURCH

Don’t know if this helps you, but 1 Horsepower is about 746 Watts, and most generators are about 90-95% efficient. So, a 10 HP generator will probably give you about 7 KW. Is that what you were asking?

#### CWatters

Homework Helper
Gold Member
The output voltage depends on the type and design of the generator. Things like the number of turns in the windings, the flux density and the rpm.

The current drawn depends on the load connected to the generator. What you probably want to know is the maximum current that the load can be allowed to draw. Fundamentally that is limited by the power input to the generator, the voltage and the efficiency of the generator. Practically it depends on the design of the generator.

What type of generator are you talking about?

#### davenn

Gold Member
What type of generator are you talking about?

a fictitious one

so, assuming that you know all of the aspects of your theoretical generator,

#### David Lewis

...assuming that you know all of the aspects of your theoretical generator, apart from the voltage and current, how would you work it out?
You would calculate the back EMF constant (Kω) of the generator. The no-load output voltage is then equal to x field flux x generator speed.

#### David Lewis

The current capacity of a generator depends on how quickly the armature can dissipate heat. The rate at which heat is produced = current2 x armature resistance. The maximum current output that still permits reasonable lifespan is estimated by the design engineer based on experience and then verified with lab testing.

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