Cold Fusion
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Yes, I read it. Didn't see anything significant for comment. Sometimes I can't tell which part is the trivial rambling.
cf
Power factor and VA vs Watts
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cf
You mean to tell me the 3 questions (actually more like 2.5 :roll
have no significant answer... Cold Fusion
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Well, the 2.5 Qs have answers. I wouldn't have considered them sigfinicant for this discussion. The questions were trivial simple. The concepts are easily derived from most normal power system models.You mean to tell me the 3 questions (from post 463 - cf) (actually more like 2.5 :roll
cf
Listen up now. The phase angle applies to the current--not the power.
I am countering besoeker's claim that instantaneous values have no phase angles. No other conclusion is possible.
Again, the claim was that instantaneous voltages and currents have no phase angles. Someone needs to provide proof of this claim. If they can't, they must be wrong!
Smart, you miss the point. I am demonstrating that phase angles can ideed be used with instantaneous voltages and currents. Choice of symbol is immaterial.
How can an instantaneous measurement be assigned anything but a scalar quantity?
How would it affect the outcome of an equation based on instantaneous measurements?
Cold Fusion
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It can't.
It won't
R found an out of print text describing a concept that has no use in power systems analsys. Who knows what that particular section of the text was trying to show?
cf
Cold Fusion
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Cold Fusion
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Oh right. Thanks for pointing out my mis-type.
There are no known models of power systems where the concept of instantaneous current having a phase angle has any use what so ever.
Just possibly, there could be some that might disagree and also have a logical explanation
Actually, the more I think about it, you and smart can insist that instantaneous current has a phase angle. And I won't say you are wrong. Of course that would be right up there with:
The moon has a phase angle. (Well, prove I'm wrong:roll
Yes, equally useless.cf
Glad you asked. Let,
v = Vm*sin(wt)
i = Im*sin(wt + phi)
p = vi = (VmIm/2)[cos(-phi) - cos(2wt + phi)]
Further identities may be used to expand the equation to 3 terms.
p is a scalar--not a phasor! phi merely shifts cos(2wt) in time.
Cold Fusion
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Wow that is interesting. So could one also say:
"i is a scalar -- not a phasor! phi merely shifts sin(wt) in time."
cf
I was not commenting on your demonstration (which is fine in my book...errrr that would be "head" for you bookworms :roll
I was commenting on...
The slightly less general form of i(t) is:
i(t) = Im*cos(ωt ? φ + θ)
where:
φ is the associated voltage phase angular delay from reference (omitted if the voltage phase angle is the reference angle)
θ is the displacement amount of the current to voltage phase angles (leading is positive, lagging is negative)
...and the others you know...
...and I also used the cosine function instead of sine... and you know why.
where:
φ is the associated voltage phase angular delay from reference (omitted if the voltage phase angle is the reference angle)
θ is the displacement amount of the current to voltage phase angles (leading is positive, lagging is negative)
...and the others you know...
...and I also used the cosine function instead of sine... and you know why.
That said, your usage of theta is the most common form.
The dot product of two vectors being scalar is a vector math limitation. In the physics world, AC power is a sinusoidal waveform when both voltage and current are sinusoidal waveforms. It therefore can be modeled as a vector or phasor if one desires.
Let's hear it.
Please indulge me and answer the questions...
I should say that a postive phi advances i(t), and a negative phi delays i(t). v(t) is our reference with an angle of zero. The fully expanded equation contains no phase shift terms at all.
All the terms are scalars.
I said there was no displacement between instantaneous values.
Let me rephrase that.
There is no phase displacement between the current and the voltage occurring at the same instant.
The power at that instant is just current times voltage.
Real and reactive components have no meaning in this context.
IMO, they actually have more meaning than total power at that instant when considering reactive loads (...but this opinion may be heavily influenced by my present disposition
).However, if our objective is to plot the data to get a "picture" of relationships, we don't really want a set of values at one and only one particular instant. Rather we want to amass a multitude of instant values over a range of no less than one full voltage cyle. I prefer two full voltage cycles. Yet, in the process, the capability of determining a set of values at one particular instant is made available to us.
Not even total power. Just power. It really is that simple.
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