THE PHYSICS OF... POWER

[FionaZuppa]

Have you measured the quality of the sinewave?
Carried out a harmonic analysis to determine its integrity?

i have not. big gens that have big inertia will likely not have impact on its output. i am not sure what type of controls may also be there.

 

[Besoeker]

i have not. big gens that have big inertia will likely not have impact on its output. i am not sure what type of controls may also be there.

I have a big dog.

 

[Phil Corso]

i have not. big gens that have big inertia will likely not have impact on its output. i am not sure what type of controls may also be there.

Inertia has little influence on Wave-shape quality! A major influence is winding pitch!

Phil Corso

 

[mike_kilroy]

I have a big dog.

Does IT eat bees?

Sent from my SM-G900V using Tapatalk

 

[Besoeker]

Does IT eat bees?

It's black and white. Not fifty shades of grey.

 

[FionaZuppa]

Inertia has little influence on Wave-shape quality! A major influence is winding pitch!

Phil Corso

if it were to spin like this pic then the sin wave would not be so sin :thumbsup:

 

[Besoeker]

if it were to spin like this pic then the sin wave would not be so sin :thumbsup:

Didn't think we were discussing sin.........but if that's what floats your boat...........

 

[ActionDave]

This thread is starting to look like the Music Game. Everybody involved picks more than just one word, other than that I can't tell the difference.

 

[iwire]

This thread is starting to look like the Music Game. Everybody involved picks more than just one word, other than that I can't tell the difference.

Here is what I have learned.

The futility of electricians arguing 'ground up vs ground down' pales in comparison to these highly educated folks arguing and insulting each other about this subject.

 

[romex jockey]

Here is what I have learned.

The futility of electricians arguing 'ground up vs ground down' pales in comparison to these highly educated folks arguing and insulting each other about this subject.

The physics of power, round & round? ~RJ~

 

[FionaZuppa]

Didn't think we were discussing sin.........but if that's what floats your boat...........

wasnt the question

Have you measured the quality of the sinewave?

were you mocking use of "sin"?

what characteristics of sine wave do you put into the quality bucket? harmonics, non-symmetrical wave across some angle, what?

 

[Carultch]

what characteristics of sine wave do you put into the quality bucket? harmonics, non-symmetrical wave across some angle, what?

Every wave shape is ultimately a superposition of a mix of sine waves. Different frequency, phases, and amplitudes. The repeating pattern is regular, when the pattern of frequencies are integer multiples of the fundamental. These are called harmonics.


So essentially, harmonics.

 

[mbrooke]

Ok, maybe I am late in the game. But why and how does low PF damage a generator? :dunce:

 

[GoldDigger]

Ok, maybe I am late in the game. But why and how does low PF damage a generator? :dunce:

It does not necessarily damage it directly, but it increases the current that the generator must be able to supply without overheating.
Also a very low inductive PF or even a slightly capacitive PF can wreak havoc with some regulator designs, causing problems with unstable voltage delivered to customers.

 

[mbrooke]

It does not necessarily damage it directly, but it increases the current that the generator must be able to supply without overheating.
Also a very low inductive PF or even a slightly capacitive PF can wreak havoc with some regulator designs, causing problems with unstable voltage delivered to customers.

I can see current itself overheating the windings outside of design parameter, but won't the extra torque be offset when the cap or inductor returns the energy?

 

[GoldDigger]

I can see current itself overheating the windings outside of design parameter, but won't the extra torque be offset when the cap or inductor returns the energy?

The extra torque is generally not a problem. It averages out to zero, BUT if most of the flywheel mass is on the prime mover side rather than the generator it would increase the dynamic torque on the coupling between them. That could be a problem even for a short term overcurrent, whether resistive or reactive. (e.g.stopping an engine driven generator by shorting the generator output is not a good idea. :happysad

 

[mbrooke]

The extra torque is generally not a problem. It averages out to zero, BUT if most of the flywheel mass is on the prime mover side rather than the generator it would increase the dynamic torque on the coupling between them. That could be a problem even for a short term overcurrent, whether resistive or reactive. (e.g.stopping an engine driven generator by shorting the generator output is not a good idea. :happysad

Ok, dumb it down for me. What is dynamic torque?

 

[FionaZuppa]

let me ask another Q.

60Hz, if i have some pure R elements, I(t)=V(t)/ΣR , yes?

and the power dissipated by any R element is I(t)²R_element = real watts = power

now i have real inductor, an R value and a X_L value, R+X_L = Z
I(t)=V(t)/Z, yes?
and the power dissipated by R is I(t)²R = real watts = power(t)
the Q is I(t)²X_L = not consumed watts = no power(t)

all agree on the above ??

do you also agree from this math that max power (real or √-1) on either of the components happens when I(t)=max, yes?

 

[mbrooke]

let me ask another Q.

60Hz, if i have some pure R elements, I(t)=V(t)/ΣR , yes?

and the power dissipated by any R element is I(t)²R_element = real watts = power

now i have real inductor, an R value and a X_L value, R+X_L = Z
I(t)=V(t)/Z, yes?
and the power dissipated by R is I(t)²R = real watts = power(t)
the Q is I(t)²X_L = not consumed watts = no power(t)

all agree on the above ??

do you also agree from this math that max power (real or √-1) on either of the components happens when I(t)=max, yes?

Well, my 2 humble cents.

I believe it is correct, however math is built (correct) around a view of what transpires across a known length a time. In reality, the math is very different at any one point in time. The generator is indeed making "power" when charging the capacitor only latter to have the capacitor send that power back.

Look at it like this. 2 scenarios. 2 gens and 2 caps. In one the cap and gen do their thing, bouncing energy back and forth. In the other the cap is attached to the gen, but immediately removed when the sine wave (voltage) peaks. Holding the capacitor, did the generator just not output energy, if not power (watts)? IMO it did, because, I can then take that capacitor into another room, and while being totally separate from the generator be able to light an LED.


Perhaps it might be the definitions bearing the ultimate weight.

 

[wwhitney]

let me ask another Q.

60Hz, if i have some pure R elements, I(t)=V(t)/ΣR , yes?

and the power dissipated by any R element is I(t)²R_element = real watts = power

Yes to the above, with the elaboration that R is a real number.

now i have real inductor, an R value and a X_L value, R+X_L = Z

Well, if you want X_L to be real, then you need to write R + jX_L = Z, where Z is complex. I forget whether X_L is positive or negative from this point of view.

Or you could just let X_L be purely imaginary, then your equation works as you've written it. I don't know what the usual convention is.

I(t)=V(t)/Z, yes?

Yes, with reservations. Certainly in magnitude I = V / |Z|.

To represent the phase shift, my understanding is that the usual method is to say that V(t) = Re V₀e^jωt, where Re means take the real part, V₀ may be complex, and ω = 60*(2π) for 60 Hz power. Similarly I(t) = Re I₀e^jωt.

With the above conventions, then I₀ = V₀/Z as complex numbers.

and the power dissipated by R is I(t)²R = real watts = power(t)

Yes.

the Q is I(t)²X_L = not consumed watts = no power(t)

Q is reactive power, and I don't know that it makes sense to consider it instantaneously.

Cheers, Wayne