No, the meter measures *power*. As others have been trying to tell
you, the torque (hence RPM) of the disk is proportional to the current
times the voltage in the respective coils. No "calculating" at all
and *certainly* there is no power factor calculated or measured.
...and reduces the neutral current, if that's important to anyone.
Big secret here, in a single phase AC circuit, Power= Volts X Amps X Power
factor, multiply by the square root of 3 for a 3 phase circuit.
Yes, to my complete suprise there are many others here more ignorant about
it than me. At least I can understand how the high leg current calculates
to more KWH then the average current of the 2 legs, others have suggested
things like magic bullets and free electricity :-)
Torque without friction or other limitations is infinite RPM so how do you
get (hence RPM)?
Without power factor you are being charged for apparent power, not true
power. Are you claiming that power meters measure apparent power, not true
I think Jim Sweet and others have it right, but I'm surprised how many
others are willing to show their ignorance when it's is obvious they don't
understand the subject. Perhaps a better explanation here: If you were
using 10 KWH between L1 and neutral, and 5 KWH between L2 and neutral, you
would be using a total of 15KWH. From what I heard another electrician
saying, the power company would charge you based on the high leg, in other
words you would be using 15KWH but the power company would charge you for
10KWH (the high leg) X 2 = 20KWH. If this were true, what balancing the
breaker box would do is draw 7.5 KWH from each leg so that you would be
using 15KWH and paying for 15KWH. Sorry for all you electrical engineer
wannabees, but that is not a magic bullet, getting power you're not paying
for, or anything like that. It would simply be using the power you're being
charged for, there is nothing wrong with that.
Sorry, I'm not generally trying to be a smart a$$ but the golden rule is to
treat others how you want to be treated. So for those that gave smart a$$
replies I reply back to you as you have replied to my post.
You have it backwards. Power factor is P/VA. Power factor is a "fudge
factor" that describes the difference between apparent power and real
power. PF is not a physical entity and is not measured directly.
Right, as you were repeating here.
Torque * RPM = HP The motor (meter disk) is doing work.
Again, you have it backwards. PF is the conversion factor not what's
being measured. POWER is being measured. Directly. No conversion
Honestly, the only one here (ignoring Proteus) that doesn't understand
this, is you.
Wierd way of looking at it, but sure. That's the way the meter is
The power company would be stealing from you. That's not allowed any
more than you stealing from them. Laws are funny that way.
It's NOT true, so saying "if it were" is a meaningless exercise.
No wannabees here. Well, perhaps you wannabe.
Of course it is. It's a promise that cannot be fulfilled. Hucksters
sell this sort of magic pill all the time.
Sorry you feel that way, but what you're posting (and continue to
post) is crap. That's not the way things work, as you've been told
here by *everyone*. Your electrician friends need to go back to
school (and I am being kind).
If Power factor is P/VA then solved for P, P = Power factor X VA.
If you have a given torque on the meter disk, what limits the RPM? Is it
generating a back EMF?
Well, I don't understand the stuff that's wrong.
There's lots of things a person can save money on or use more efficiently
and it's not illegal even though it is pretty near stealing. One example is
a 20oz soda often costs more than a 2 liter bottle of the same soda.
Nobody is selling anything, the guy telling this is not trying to get
business balancing breaker boxes or anything like that. We work at as
electrical techs in a factory repairing automated manufacturing machines,
not wiring or rewiring houses.
Well, it was you that told me my calculation using power factor was wrong
but then gave the same formula solved for power factor instead of power. My
education was in electronics technology and we didn't go into the details of
power meters and such, that is why I bring my question here. I don't have a
problem being told that what I heard is not how a power meter works, I have
a problem with those that try to tell me that a meter could not work that
way or if it did then balancing the load would be like stealing electricity.
None of us are telling you that meters *could* not work that way, or
that *if they did* work that way you would not be correct. What we are
telling you is that meters *don't* work that way, so speculating what to
do if they did is like speculating if the moon were made of cheese how
best prepare it to eat. We know that it's not, so why worry about what
to do if it is?
Given the way meters *do* work (they accurately measure power used),
getting them to read less (not accurate, false reading) is stealing
power. If the meters were ever behaving in a manner that caused you to
get billed for power you did not actually use, regardless of the load
balance, that would be fraud on the part of the power company. Again,
this is irrelevant outside of this imaginary situation because this is
not how they actually work.
I'm not sure what is so difficult about this concept. There is nothing
to optimize, the rest of the discussion is a hypothetical (imaginary)
I agree, if meters are accurately measuring the power used then there is
nothing optimize as far as the power bill, it would only help to get the
full capacity from your service. I just don't understand when I post
something about using the power I'm paying for (based on being misinformed
about the operation of a power meter) others want to turn it into me wanting
to steal power and such.
Nonsense. Ever see a 'power factor meter'?? I have, on old switchgear
systems. These only measured the phase-based power factor (harmonic
content wasn't a problem in these old systems). But they simply
developed a position based on the phase difference between the applied
voltage and current (one input polarized a moving vane in a magnetic
field created by the other input). Because the position of the needle
actually showed the phase angle, the meter face was marked in a cosine
pattern (i.e. the distance between 0.9 lagging position and the 0.8
lagging position was small, but the distance between 0.1 lagging and 0.2
lagging was larger).
The position didn't vary with the magnitude of the voltage or current,
only the phase relationship (of course if current was below a certain
threshold, the meter wasn't reliable)
What percent error is typically caused by ignoring harmonic content? Do the
harmonics fool the utility meter or how does my power meter deal with
harmonics? It just seems logical that if a utility power meter can measure
true power, and a meter can measure apparent power (VA), then why should it
be so difficult to measure power factor?
Motors, inductive loads, voltage leads current, capacitors, current leads
voltage. Is a switching power supply more like a capacitive load or
inductive load? I'm curious, I installed a 10HP variable frequency drive on
my retrofitted CNC lathe. I ran the motor at idle and the drive showed 13A,
but a meter only measured 5A on the line side. I have heard that the reason
for this is that the drive handles the power factor problem, drawing closer
to true power from the supply. If I understand correctly, a VFD is sort of
like a 3 phase SMPS with the motor being the inductors in the circuit. Just
wondering how this affects my household power factor versus other motors
running from the line.
Also, before using solid state drives to get 3 phase from single phase, I
used an old 10HP 3 phase motor to make my own rotary phase converter. I ran
240V into two of the legs and am able to run my shop from L1, L2, and the
3rd leg of the running motor. I use a single phase motor to spin the 3
phase motor up and then switch on the power. This thing drew a lot of amps
until I installed some motor run capacitors to balance out the voltages. I
don't have drives for all of my machines yet but I do for the ones I use the
most, they seem to be a real nice way of running 3 phase equipment from
Neither. It's a harmonic load. ;-) Uncorrected it has a very crappy
A fully loaded motor should have a PF pretty close to unity. What any
particular VFD does to it is anyone's guess. I suggest you buy a
"Kill-A-Watt" or "PowerAngel", or some such. These things are about
$25 and will report V, A, VA, W, PF, F, kWH, and H (did I leave
anything out?). You can then play with various loads to get a feel
for what they're about.
Several of the guys who answered you are probably EEs. They
don't generally say much about it. Once in a long while, one might
mention something he did in college or something about their
certification. They don't have to brag about it. They'll generally
know by reading each other's writing. They'll know in an instant I'm
not one if the subject is at all technical.
I didn't see much that looked like wise assed remarks. There
wasn't anything close to the flames I've seen other places. People
are just stating facts.
The public service commissions or possibly the states' attorney
generals should be all over this if it was real.
I know scales at farmer's coops are tested for accuracy by the
state. Gas pumps have stickers on them assuring their accuracy. States
have bureaus of weights and measures to make sure things are according
to hoyle. Why would they ignore the utility companies?
What about all the lawyers running around? Think of the money a
lawyer could make from a class action lawsuit if he won against a major
utility. Here's a list of some of the things lawyers have sued for:
One example there is a lawsuit against the makers of Froot Loops
because they don't contain fruit.
Not an EE, and I don't play one on TV.
Maybe you're not an EE but you gave a better reasoned answer than many.
Stating that a KWH meter does not operate based on the highest leg is a good
answer. Comparing balancing a breaker box to trying to steal electricity or
a magically creating electricity is absurd.
I'm not an EE either but I did electrical controls design and programming
for many years and still haven't used close to 10% of what I learned to get
an AAS. I have worked for and with both PE's and EE's and have learned a
lot from many of them, but not on utility meters, it was always more in the
industrial automation field.
Go back and read over the replies again because nobody (aside from
perhaps one of the trolls) has ever said that is the case. Trying to
balance the breaker box is absolutely not stealing, nor is it magically
creating electricity. The simple fact is that it will have zero
measurable effect on the meter reading.
It was simply stated that since the meter already reads correctly,
anything that did cause it to read slower (which does not include
balancing) would be stealing power because given it already measures
correctly, to get it to run slower without actually using less power
would mean you are using some power that it is not measuring. Again,
balancing your panel will *not* cause this to happen.
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