Okay, but you still have instantaneous values for one cycle... not just a set of values for a single instant. Why can we not use the complete data set [and known relationships] to perform calculations that yield other [derived] instantaneous values? The values obtained would still be instantaneous and correlated to the original data set.
Power factor and VA vs Watts
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Okay, but you still have instantaneous values for one cycle... not just a set of values for a single instant. Why can we not use the complete data set [and known relationships] to perform calculations that yield other [derived] instantaneous values? The values obtained would still be instantaneous and correlated to the original data set.
For each instant of that cycle, yes. Not an instantaneous value the complete cycle.
Because the complete data set for one cycle requires the passage of time.
The passage of time and instantaneous are mutually exclusive terms.
Aside from being impossible, I don't believe anyone is under that impression.
No one is saying otherwise. What I'm saying is we can use the complete data set to determine other related instantaneous values. You are saying, or so it seems, that we cannot... and I cannot fathom why.
The complete data set requires the passage of time.
Let me try with an analogy.
I can tell you that I traveled 100 miles in 100 minutes. From that you can readily determine that my average speed was 60 mph. What you can't do is calculate the speed that I was doing at any point of that journey.
While that's a good analogy for something such as trying to determine peak kW demand from monthly kWh reported on one's bill, the analogy as stated doesn't fit here.
Here we have, using the same storyline, a complete record of travel, especially your speed at any one instant. We can determine your acceleration, deceleration, and constant speed rates and duration. We can even tell when you had to stop and relieve excess bladder pressure.
Exactly.Here we have, using the same storyline, a complete record of travel, especially your speed at any one instant. We can determine your acceleration, deceleration, and constant speed rates and duration. We can even tell when you had to stop and relieve excess bladder pressure.
Just like the power waveform I gave in post #156.
That shows power increasing, decreasing, positive , negative, and zero. But just power.
Likewise, the complete record of travel shows speed and rate of change of speed. But just speed. Not speed broken down into real and reactive components.
What if your vehicle was hybrid powered, electric and gasoline, and we had instantaneous info on your MPG?
Could we determine from the instantaneous MPG which subsystem was powering the car at any particular instant?
In comparison, we not only have instantaneous power info, we also have instantaneous voltage and current info.
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On the other hand, real and reactive power can be determined from just p(t) alone. What can't be determined without voltage and current info, is whether the reactive power is leading or lagging the real power...
If:
S? = P? + Q?
...and we let their counterpart instantaneous values be p(t), p'(t) and q(t) respectively, coupled with the following relationships:p(t) = p'(t) + q(t)
avg[p(t)] = avg[p'(t)]
p'(t)_min = 0
φ_p't ? φ_q(t) = ?π/2 or ?90?
...then we just solve for the instantaneous values...avg[p(t)] = avg[p'(t)]
p'(t)_min = 0
φ_p't ? φ_q(t) = ?π/2 or ?90?
mivey
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That's what I was thinking
But certainly more than one piece of information can be gleaned from the data set.
weressl
Esteemed Member
A cycle, a half cycle or ANY time period contains INFINITE number of instantaneous values. What is so difficult to understand about that? It is both fundamental and elementary.
As soon as you average ANY of these instantaneous values, you can no longer call the instantaneous. As soon as you take one instantaneous reading of voltage and another reading of instantaneous reading of amperes at a DIFFERENT time, you can determine power factor, etc. as long as you KNOW the time difference between the two 'instantaneous' readings. (As we agreed, instantaneous reading can NOT be taken, it is only theorethical. It is akin to the observation of leptons.)
I don't recall saying I had any difficulty in this respect
Have to disagree. The average is not instantaneous, but the instantaneous values remain instantaneous.
Truly instantaneous cannot be taken. However, we can take instantaneous measures within the limitations of equipment resolution and interpolate intermediate theoretical values.
Modern recording equipment has the ability to take an exorbitant amount of samples in a short amount of time. I think it was the Fluke 127 I was looking at that takes 2.5GS (giga-samples) per second. For a 60Hz sinusoidal signal, I'd say that is more than enough to confirm any "grounded"
theoretical analysis.Any relation to the short gold hording creatures?
How do you determine from say zero mpg whether the vehicle was running in EV mode or just decelerating?What if your vehicle was hybrid powered, electric and gasoline, and we had instantaneous info on your MPG?
Could we determine from the instantaneous MPG which subsystem was powering the car at any particular instant?
The instantaneous power comes from instantaneous current times instantaneous voltage. It isn't an also.
First, I must say that it is only an analogy. Second, I am not familiar with the exact workings of a hybrid vehicle... but if I were, I'm assuming I could make the determination based on MPG. Currently my assumption would be if the rate is zero MPG, then it is definitely not being power by either engine :roll:
But it is an also. If it were not, we'd have instantaneous [apparent] power info without instantaneous voltage and current info. We can glean more than just instantaneous [apparent] power info from the voltage and current info.
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Instantaneous current times instantaneous voltage is the power at that instant. Nothing more. Just power. It doesn't come in different flavors. It is just power.
chris kennedy
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Whats for lunch?
jumper
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Grilled alpaca, sauted coon hash with BBQ sauce, and deep fried chitlins. Good eats.:grin:
Hameedulla-Ekhlas
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chris kennedy
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I have a brat wurst and some boiled green peanuts. Ekhlas, I don't care for food thats looking at me.:roll:
Hameedulla-Ekhlas
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chriss: it is just a joke hope to not mind it :grin:
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