Power Factor Discussion

[STEVETERRY]

This thread began as a side conversation in the thread: Experience with Philips Ambient LED in the Home. I have split it out into it's own thread to make it easier to search for in the future.
Gaff

Like many of you I have been playing around with LED bulbs in the home. While I have had good success in a few applications like under counter task lighting, I had not found anything that I really liked for replacing a plain old incandescent A lamp.

Well - that has changed. at LDI last year Philips was showing a bulb which looked funny, ( it has a very YELLOW appearance) but seemed like it might bear further investigation. I never saw one in the local stores, but I ran into it on amazon the other day.

Amazon.com: PHILIPS Endura LED 12.5 Watt A-Shape A19 LED Dimmable Light Bulb ~ 60 watt incandescent equivalent: Home Improvement

I got two and tried them in a ceiling unit, and I have to say that I am very happy. The color temperature is a very warm 2700K. Skin tones look good to my eye. It seems that it takes a fraction of a second longer to turn on that the old incandescent unit did, but it gets to full bright immediately.

I am a happy camper.



If you are looking for an LED to replace your standard 60 to 75 watt A lamp - you should give these a look.

It's interesting to me that no post in this thread mentions power factor. In their effort to get the cost of LED bulbs down, manufacturers have sacrificed power factor. Many of these LED bulbs have very poor PF--sometimes as low as 0.4. This has the utilities quite scared, and their method of controlling this will be:

A. Change the standards to require higher power factors. This is already happening, led by the Canadians in North America. This will make LED bulbs cost more.
B. Charge you a hefty premium for lower power factors.

So, when selecting an LED bulb, I think you need to include power factor in the payback equation.


ST

[David Ashton]

And it isn't just a simple power factor issue, with the switch mode power supplies, the neutral current problems we are accustomed to with theatre dimmers could become mainstream, causing transformers to overheat and the neutrals having to be increased in size.

[FMEng]

And it isn't just a simple power factor issue, with the switch mode power supplies, the neutral current problems we are accustomed to with theatre dimmers could become mainstream, causing transformers to overheat and the neutrals having to be increased in size.

Most homes don't have enough lighting to make this a concern. It is a factor in larger buildings that electrical engineers incorporate into the design.

Both compact fluorescent and LED radiate a fair amount of RF from their power supplies. The FCC seems oblivious to it, but various radio systems are affected. Ham radio is suffering from increasing noise levels on many bands. AM broadcast is sinking due to a sea of noise, and FM broadcast is next.

[STEVETERRY]

And it isn't just a simple power factor issue, with the switch mode power supplies, the neutral current problems we are accustomed to with theatre dimmers could become mainstream, causing transformers to overheat and the neutrals having to be increased in size.

Yes, indeed! And unlike phase control dimmers that generate the most harmonics at half power, switch mode supplies in ballasts and LED drivers generate harmonics at full power.

ST

[David Ashton]

It's far from being just a lighting issue with switch mode style microwave ovens and inverter air conditioners, all computer supplies, amplifiers, the list is endless, maybe we'll soon get a rebate for incandescent lamps.

[JD]

It's far from being just a lighting issue with switch mode style microwave ovens and inverter air conditioners, all computer supplies, amplifiers, the list is endless, maybe we'll soon get a rebate for incandescent lamps.

Agreed!
With all the emphasis on energy savings, the new appliance norm may fall to .5pf ! (How long before a washing machine motor becomes a small efficient 3 phase motor driven by a small inverter/driver circuit?) On the other hand, newer guidelines push for "home run" neutrals on all circuits on the home. (and away from the old x/3 with a common.) When only two wires are involved, both would carry the same current.

So, will there be push-back? Well, if the government continues along its same course, they may simply mandate that power companies accept this new norm in order to promote the efficiencies. After all, isn't that how this whole CLF/LED thing started?

[tjrobb]

JD - IIRC, Energy Star guidelines are 0.5pf or greater for CFL lamps and resi ballasts. Can't recall anything regarding LED's.

[JD]

JD - IIRC, Energy Star guidelines are 0.5pf or greater for CFL lamps and resi ballasts. Can't recall anything regarding LED's.

Can't imagine LEDs are any better! Welcome to the .5pf world!

Odd thing is, there are regulations on permanent indoor fixtures, at least in commercial buildings, that mandate 0.9pf or better. Can't remember the specifics, but if I remember right, this is not something through the NEC. Ran into this issue a few years back with some outdoor HID roof fixtures. Although these were "Outside" (which would normally be exempt) they were attached to the structure, so we had to buy corrected fixtures.

It will be interesting to see how this all washes out. On one hand, low pf, on the other hand, massive energy savings. Which will win?

[David Ashton]

Power Factor relates to the phase relationship between voltage and current, you can be chopping the guts out of a sinewave and causing all kinds of harmonics without affecting the power factor as in standard theatre dimmers.

[JD]

Power Factor relates to the phase relationship between voltage and current, you can be chopping the guts out of a sinewave and causing all kinds of harmonics without affecting the power factor as in standard theatre dimmers.

Actually, except at 100%, phase chop dimmers have a horrible power factor.

Power Factor Correction

"Another notorious non-sinusoidal current draw is the popular phase controlled light dimmer, which uses a TRIAC or SCR to reduce the RMS voltage to the load by turning on partway through the half cycle. Not only is the current waveform highly non-sinusoidal, but it is also out of phase with the voltage supply. Hence, these loads have a non-unity power factor"

Think about a dimmer set at 33%. The full power draw is out of phase with the waveform, drawing 100% of its load in the last 33% of the AC cycle. (assumed liner curve)

[David Ashton]

I don't buy that line of argument, when the same light is at full it has pf 1 and as you dim it the pf goes down? I would want to see some convincing evidence to back that theory.During the time the current is flowing it is in phase with the voltage, so the quote you showed is wrong. The same quote apears on 7 different forums, so there's some plagiarism going on, but it's still wrong however many times it's copied.

[JD]

I don't buy that line of argument, when the same light is at full it has pf 1 and as you dim it the pf goes down? I would want to see some convincing evidence to back that theory.During the time the current is flowing it is in phase with the voltage, so the quote you showed is wrong. The same quote apears on 7 different forums, so there's some plagiarism going on, but it's still wrong however many times it's copied.

Ah, but it isn't! At peak voltage, no current is flowing! Power only flows in the last 1/3rd of the waveform, thus giving the dimmer a horrible power factor!
Another example of this is the computer supply, which IS drawing peak current at the peak voltage. What gives it a low power factor is that it is only drawing power during about 10% of the waveform. In this case, the power draw is in-phase, but disproportionate.

Let's say that a 500 watt load is operating at 33% and is drawing 150 watts.
It is drawing the 150 watts at about 50 volts RMS. That works out to 3 amps. With a pf of 1, 150 watts would be drawing 1.25 amps, so the dimmer is operating at a pf of .42

The reason this is not a factor in dimmer design is that the circuit would be expected to handle 4.12 amps for the 500 watt load. Thus, the 3 amp draw does not require any attention.

Power companies want the voltage and current draws to be in sync. The failure to be in sync is why we end up (on three phase) with triplen harmonics, and the resulting neutral over-current. Again, this is a factor that comes into play due to the off-phase current draw occurring at lower dimmer settings.

Transformers have been developed to reduce triplen harmonics, but with great irony, they can't be used for lighting equipment as their action throws off the ZVD in the dimmers! http://www.etcconnect.com/lightminds...nic_Filter.pdf

[David Ashton]

OK so are you telling me that if I put a power factor meter on a dimmer then the meter will go from zero to one as I bring up the dimmer, I don't think so, I've never seen any indication of this when using generators but I have a power factor meter somewhere in the factory, I'll dig it out and try it, but the logic of how wave chopping affects power factor,[which is a phase change phenomina] escapes me.
"Let's say that a 500 watt load is operating at 33% and is drawing 150 watts.
It is drawing the 150 watts at about 50 volts RMS"
That assumption is way out because of resistance change in the filament anyway, a subject we covered in depth in the preheating argument.Probably over 250 watts at 33%
Quote
Default Re: Preheating Conventionals?

Please consider, a 1000 watt 240 volt T19 on a dimmer{for 120v thinkers just halve all the figures} It has a cold resistance of 3.8 ohms and a hot resistance of 57.6 ohms. A typical dimmer will feed 1.65v at "0" and drive .35A putting 2.24 W into the lamp of preheat.
@ 13V you can see the barest glow in the filament and are drawing .96A and 12.6W
@30V you can see a real glow and are drawing 1.5A and 45W
at 60V you begin to get some output but at 1/4 voltage you are drawing 2A or nearly half the "full" current
@80V which is 1/3 voltage you are drawing 2.3A which is more than half the full load current and is also the point at which the dimmer starts to interact with the other dimmers on other phases.
This is why running all your dimmers at 1/3 is the worst thing you can do to your neutrals.

[sk8rsdad]

John and David, you are both right, and you are both describing different situations that result in low power factor.

Pulling out the textbook on power factor, we learn that it is the ratio between the active power and the apparent power.

There's this other component called reactive power that is worth understanding, which is a result of inductance or capacitance in the load, resulting in a phase shift between the voltage and the current, and that's the situation that John is describing. It is certainly present in the system to some degree, but is not the cause of the low power factor of switched circuits. If we were dealing with linear loads like motors, heaters, or the like then power factor correction would involve adding capacitors or inductors to remove the reactive component from the equation.

In the case of switched dimming, David's description is more applicable because the low power factor is due to the non-linear waveforms produced, and the harmonics arising as a result. The current required is higher than anticipated for the power available to the load. The current and the voltage are mostly in phase, but the waveform is distorted. Those harmonics use energy but do not contribute to providing useful power to the load. That energy gets dissipated, mostly as heat, in other parts of the system, like the transformer and wiring. So you can think of distortion power factor as a ratio between the fundamental harmonic current, measured as RMS, to the total load current. In North America that would be the 60Hz component versus the current with all the higher order harmonics.

[JD]

If (RMS line voltage X RMS amps = watts) then we have a power factor of 1
Otherwise (RMS line voltage X RMS amps X power factor = watts)

With 150 watts being dissipated at a late phase equivalent of 50 volts drawing 3 amps, given rounding, which one of the following equations is true:

A) 120 X 3 = 150
or
B) 120 X 3 X .42 = 150

[David Ashton]

power factor is Watts/VA now in the article it states,
"Not only is the current waveform highly non-sinusoidal, but it is also out of phase with the voltage supply. Hence, these loads have a non-unity power factor" but magically at full it reverts to pf 1"
How can the current be out of phase with the voltage, a triac is a switch, it can't change phasing like a capacitor or inductor.
I get that distortion can lose energy and cause a "distortion power factor" but that is not what is being stated.

[epimetheus]

I've got a shoebox dimmer, 750W S4 PAR, and a Watts Up meter at the house. This experiment is going down tonight (time permitting).

[JD]

power factor is Watts/VA now in the article it states,
"Not only is the current waveform highly non-sinusoidal, but it is also out of phase with the voltage supply. Hence, these loads have a non-unity power factor" but magically at full it reverts to pf 1"
How can the current be out of phase with the voltage, a triac is a switch, it can't change phasing like a capacitor or inductor.
I get that distortion can lose energy and cause a "distortion power factor" but that is not what is being stated.

yes, 120 X 3 X .42 = 150
or
150 /(3 x 120) = .42
or
150/360 = .42 (w/va = pf)
(rounded) Same equation.

Simply put, the "phase" of the outgoing waveform now lags the source AC waveform:

Current draw now lags waveform phase,

[David Ashton]

yes, 120 X 3 X .42 = 150
or
150 /(3 x 120) = .42
or
150/360 = .42 (w/va = pf)
(rounded) Same equation.

Simply put, the "phase" of the outgoing waveform now lags the source AC waveform:

Current draw now lags waveform phase,

no it doesn't "lag" it is a resistive load and in phase, the fact that you have a picture with a trailing edge dimmer is not a "lagging" situation, if you use a leading edge dimmer does that give you a "leading" current? clearly not. Using 2d pictures to convey 3d concepts does not work.
Why put "phase" in inverted commas, it's either phase or it isn't and this clearly isn't, any more than ""Not only is the current waveform highly non-sinusoidal, but it is also out of phase with the voltage supply." is totally wrong, I can't figure out why this is so hard to understand.I also can't understand why it keeps getting repeated.

[DavidNorth]

no it doesn't "lag" it is a resistive load and in phase, the fact that you have a picture with a trailing edge dimmer is not a "lagging" situation, if you use a leading edge dimmer does that give you a "leading" current? clearly not. Using 2d pictures to convey 3d concepts does not work.
Why put "phase" in inverted commas, it's either phase or it isn't and this clearly isn't, any more than ""Not only is the current waveform highly non-sinusoidal, but it is also out of phase with the voltage supply." is totally wrong, I can't figure out why this is so hard to understand.I also can't understand why it keeps getting repeated.

Correct. Voltage and current are completely in sync in time. However, all of the harmonic component while being dimmed is combined into what is called "displacement power factor," as Sk8rsdad mentions. This type of power factor is created with non-linear loads such as power-rectification or power-modification equipment. In fact, that is where we started the thread in regards to LED power supplies but this also applies to fluorescent ballasts, computer power supplies [all switch-mode power supplies], and all wave-chopping power equipment, including phase-chopping dimmers.

I think what may have been confusing here is the description of the chopped waveform. Looking at zero-cross, current and voltage are in syne. Looking at peak energey in current versus voltage, they are not. So yes, the chopped waveform is in zero-cross sync BUT the missing component of the waveform works to help create our harmonic friends.

One note - most dimmable FL ballasts list a power factor of 0.9-0.95 but that does not hold true when dimmed and indeed I have measured them easily going down to 0.5-0.2 in some cases. Switch-mode supplies are such a huge non-real power suck it is amazing that power companies don't do more to partner with electronics designers and the government to help solve the non-usuable energy waste problem. But then, that costs money too.

Back to the topic-ish...

We have to remember that the load on the line feed is the combination of the dimmer and the lamp, and in the case of a phase-controlled dimmer, we now have a non-linear load. A linear load lamp, with a true switch, not a phase-controlled switch, is a linear load.

If this doesn't help in understanding how this type of power factor exists, would screen shots of a PF meter help? Unfortunately I didn't have time to hook this up yesterday but I can certainly do it on Monday. If you can get to your meter, you will indeed see what has been described. I'm really curious what Epimetheus finds on his Watts Up? meter.

David

[epimetheus]

I did set this up last night, but I quickly realized that the Kill A Watt meter that I have is powered off the circuit that it is measuring. The meter didn't come on until I had the dimmer up to about 30%. This makes me seriously question the accuracy of any reading that it showed. For the record, the Kill A Watt didn't show a PF lower than 0.9 throughout the part of the dimmer range that it was actually powered. I still don't think that is a definitive result since the Kill A Watt is not designed to accurately measure this type of load.

I might investigate further but I don't have a power analyzer that would make this easy.

[JD]

I did set this up last night, but I quickly realized that the Kill A Watt meter that I have is powered off the circuit that it is measuring. The meter didn't come on until I had the dimmer up to about 30%. This makes me seriously question the accuracy of any reading that it showed. For the record, the Kill A Watt didn't show a PF lower than 0.9 throughout the part of the dimmer range that it was actually powered. I still don't think that is a definitive result since the Kill A Watt is not designed to accurately measure this type of load.

I might investigate further but I don't have a power analyzer that would make this easy.

With a shoebox dimmer, put it before the pack. Post pack, it has no point of reference to the original waveform.

[epimetheus]

Doh! Why didn't I think of that?

[epimetheus]

Ok, so here are the results with the Kill A Watt on the supply side of the dimmer. The dimmer is a Leviton D4DMX, fixture is a S4 PAR with a HPL750/115 lamp.

%	Voltage (V)	Current (A)	Power (W)	Apparent Power (VA)	PF
0	120.3	0.02	2	2	0.99
10	119.7	2.11	35	251	0.13
20	118.8	3.25	118	388	0.30
30	117.9	3.82	183	452	0.40
40	117.4	4.27	248	503	0.49
50	116.4	4.83	349	564	0.61
60	115.2	5.36	464	615	0.75
70	114.1	5.75	570	657	0.86
80	113.1	6.01	645	686	0.94
90	112.7	6.15	685	694	0.98
100	112.7	6.20	699	699	1.00

I did have the Kill A Watt and the dimmer on an extension cord, so that is probably accounts for the voltage drop over the dimmer range.

As far as why utility companies aren't screaming about the low power factor, I think is has a lot to do with duration and timing. I would think that most of the time when a dimming system is utilized, it's in the evening or on weekends (non-peak times). Also, the load duration at this low power factor is generally temporary. A traditional utility meter (non smart meter) does not record power factor. So the utility won't notice this power factor issue unless the customer in question is a significant portion of the distribution feeder load (thus allowing the feeder relay at the substation to record the low power factor on the feeder). Smart meters give the utility detailed information about each individual customer and have the ability to identify a low power factor load more quickly than before the smart meter revolution. Whether utilities are using the smart meters to alarm on low power factor is another question. Also, I believe commercial circuits have had "smart" meters for much longer than residential circuits.

[JD]

Thanks for running the real world test!

Kind of what I expected. I think I estimated .42 at 33% (1/3) and 30% came in at .40, 40% came in at .49 so that looks about right.
I think I used 500 watts in my scenario, but the numbers should remain consistent regardless (within reason) of lamp wattage.
(Really was just a guesstimate)

I think one reason that power companies are not screaming is because it is a transitory issue and pf is 1.00 at 100%

[David Ashton]

this experiment relies on the Kill A Watt device being able to give an accurate measurement of VA in a chopped ac waveform. This can only be done, in my experience, with expensive true rms meters.Maybe Mr Steve Terry could run the same test with his resources and see if the same answer. Power factor is a simple concept with the current out of phase with the voltage and I still fail to see how a switch can put the current out of phase with the voltage. Calling the harmonic losses "displacement power factor" is confusing as it does not relate to the phase relationship."displacement power factor" is not a constant like normal PF which is easily corrected but a complex function which changes as the load does.
"We have to remember that the load on the line feed is the combination of the dimmer and the lamp, and in the case of a phase-controlled dimmer, we now have a non-linear load. A linear load lamp, with a true switch, not a phase-controlled switch, is a linear load."
No a lamp is absolutely not a linear load, and a phase conrolled switch does not change the phase of the current in any way I can understand.
It certainly stuffs up the waveform and causes all kinds of harmonic problems which cause losses similar to power factor problems but it still seems a misnomer to say a dimmer has a power factor.Unless you call in the ""displacement power factor" concept.

[David Ashton]

OK it's 1.40 am and I just figured out what is happening here, the Kill a Watt machine is on the supply so it is using the supply voltage to get the V, but the voltage is chopped after the Kill a Watt which reduces the current, so it thinks that reduction is due to phase difference and calculates accordingly, but if you put a VA meter across the load it would read almost exactly the same as the watts, a electromechanical PF meter like mine does not read this as it is looking for phase change as in the conventional PF situation.
So using PF to describe two totally different processes is very confusing and is a function of the measuring instrument.
Going back to bed now.

[someguy98457]

So I think I understand where the confusion is coming. Typical power factor problems come from current and voltage being out of "sync". Basically the thing that is being powered is taking those two things in at an offset to what is being supplied, your sine waves end up out of sync and bad things happen, harmonics etc. However in the Dimmer a different thing is happening because you are chopping the sine wave, for the portion of the sine wave that is not chopped, the sinwaves sync up and everything is happy, however for the portion of the sinewave that is chopped the supply has no where to go, causing it to be in demand but not used by the light/dimmer, hence it is cancelled out on the other side of the sine wave by its inverse that is also not being used by the light/dimmer, hence it counts as power consumption but not actually used. Thus why it can still be measured in the same way as power factor, but actually somewhat different.

Ish? Kinda correct? Stab in the dark.

[Chris15]

The root cause of the confusion over the power factor is our old friend harmonics...

By Fourier's theorem, any periodic waveform can be decomposed to a sum of sine and cosine waves at the fundamental frequency (ie. 1/ the period) and integer muliples of that frequency, plus a DC offset.

To say that pf = cos (angle between voltage and current) is true ONLY when dealing with sinusoidal waveforms at the fundamental frequency only.
Add non trivial harmonics and all bets are off. (Note that even in a passive circuit you will get harmonics - magnetising currents in inductances are one such cause)

S = P + Q will always hold true, but this is [a] a complex number and [b] P is really Ptotal = Pf + P2f +P3f + P4f + ... where f is the fundamental frequency and likewise for Q.
P + jQ = |S| with some angle theta. It is THIS angle that is what needs to be used for the pf= cos theta.

For the sake of high school maths, |S| = SQRT(P^2 + Q^2) and theta = inverse tan (Q/P).

Utilities hate reactive power. It's a lose lose situation for them because it doesn't do any useful work but it does heat up their lines and then they have to upsize their infrastructure to cope...

As we see more and more inverter drives on anything that moves, harmonic hash on the grid is going to get worse and worse.
I do hope your filter capactitors in your audio gear work well

[someguy98457]

Right, but the "non trivial harmonics" are generated by the unused sine wave bouncing off the switch, not something inherit in the switch itself as oppose to in a electrical motor.

[David Ashton]

In the traditional PF the load gets full voltage and full current, but out of phase giving losses but the cable is still taking the full current and so has heating losses.
In the dimmer situation the load gets a reduced voltage and the PF is caused by the difference between the supply voltage and the load voltage,[which is driving the current through the load]
Just to complicate things further there is likely to be both effects in play.
Plus "quote" "the non trivial harmonics" are generated by the unused sine wave bouncing off the switch, not something inherit in the switch itself as oppose to in a electrical motor.
I think it could be useful to not lump all these effects under the simple term power factor.
I think it would be fair to say that no cheap measuring instrument could measure this complex situation.

[STEVETERRY]

triplen harmonics[/AUTOLINK], but with great irony, they can't be used for lighting equipment as their action throws off the ZVD in the dimmers! http://www.etcconnect.com/lightminds...nic_Filter.pdf

Actually, the problem device in the article is a tuned filter stuffed into the transformer cabinet, which won't work. However, a harmonic mitigating transformer works great with phase-control dimmers:

Transformer, Harmonic Mitigating - ControlBooth

ST

[DavidNorth]

I think it could be useful to not lump all these effects under the simple term power factor.
I think it would be fair to say that no cheap measuring instrument could measure this complex situation.

As the power company sees these effects all as different components of the larger term power factor, I think it is indeed fair to look at them all together. After all, isn't power factor really what the generating plant is concerned about?

I have a Fluke 41 and a Dranetz PowerGuide 4400 [non-cheap at roughly $9k] that I can run today to show you the data. The Dranetz is able to show W, VA, VAR, TPF, and DPF. These are all important to the power company, especially TPF [True Power Factor] and DPF [Displacement Power Factor] which are indeed measurable and not merely a concept as mentioned previously.

Now what we haven't talked about is what makes it back through the feed transformer to the power grid - and depending on who owns the transformer, that discussion may be moot - but this discussion is specifically around what a dimmer and load would provide to its specific feed.

Let me know if there are any concerns soon since we will run these measurements today, if I have enough people back from vacation.

Thanks,
David

[epimetheus]

I'm very curious to see the results from the Dranetz. My results from the Kill A Watt seem plausible. I'm going to make a rig tonight to verify the Kill A Watt's current and voltage measurements with my Fluke RMS multimeters.

Personally, I think it's pretty easy to see that the current waveform on the input side of the dimmer is out of phase with the voltage when the load is dimmed just by looking at the peaks. I agree that the chopped output waveforms match the input waveforms once the switch closes, but if you compare the peak of the input voltage waveform to the peak of the input current waveform, it's very easy to see that they are out of phase.

[DavidNorth]

I'm very curious to see the results from the Dranetz. My results from the Kill A Watt seem plausible. I'm going to make a rig tonight to verify the Kill A Watt's current and voltage measurements with my Fluke RMS multimeters.

The setup:

Sensor SR12+ with CEM+
Configured with Linear curves and no regulation
3 Source Four PARs with 575W lamps
1 PAR in a dimmer on each phase
3 Phase power feed at 120/208V
SmartFade console
Dranetz PowerVisa 440 [remembered that wrong this morning] Power Analyzer with 4 voltage probes and 4 CTs with ground ref tied in at power feed to rack.

We recorded readings with all the dimmers running to the same levels - 20%, 35%, 50%, 75% and 100%. We also ran each dimmer individually, but saw the same readings on each phase as with all dimmers running to the same levels, and therefore did not record them.

20%
Phase	Watts	VA	VAR	TPF	DPF
A	77.78	238.3	146.9	0.326	0.480
B	69.19	280.6	146.0	0.247	0.445
C	41.92	227.5	140.6	0.184	0.312

35%
Phase	Watts	VA	VAR	TPF	DPF
A	138.4	330.8	204.4	0.418	0.570
B	142.1	363.6	196.9	0.391	0.558
C	105.5	317.4	198.0	0.332	0.487

50%
Phase	Watts	VA	VAR	TPF	DPF
A	229.7	419.3	244.7	0.548	0.680
B	238.3	439.9	228.7	0.542	0.713
C	198.2	399.4	236.9	0.496	0.641

75%
Phase	Watts	VA	VAR	TPF	DPF
A	384.5	520.5	255.4	0.739	0.830
B	394.0	527.5	226.9	0.747	0.866
C	353.0	492.3	244.3	0.717	0.822

100%
Phase	Watts	VA	VAR	TPF	DPF
A	557.0	601.4	165.9	0.926	0.958
B	567.1	602.0	116.3	0.942	0.980
C	526.2	568.8	149.7	0.925	0.962

And here are a couple of pics from the meter.

Now we do have this still setup so we can provide other data if desired including phasors, harmonics graphs, etc. It's a nice meter and fun to play with. And why do we have it? Well, from time to time we run into odd power issues on job sites so we decided to station one meter here and one in the UK. We have them packaged with instructions and can leave them in place for a period of time to even gather anomolies and glitches. Then, people on site can email us the files and we can analyze them here. Technology is cool.

Ok, so how are we feeling about the data?

David

[JD]

Ok, so how are we feeling about the data?

Looks right on the money to me.

[STEVETERRY]

The setup:

Sensor SR12+ with CEM+
Configured with Linear curves and no regulation
3 Source Four PARs with 575W lamps
1 PAR in a dimmer on each phase
3 Phase power feed at 120/208V
SmartFade console
Dranetz PowerVisa 440 [remembered that wrong this morning] Power Analyzer with 4 voltage probes and 4 CTs with ground ref tied in at power feed to rack.

We recorded readings with all the dimmers running to the same levels - 20%, 35%, 50%, 75% and 100%. We also ran each dimmer individually, but saw the same readings on each phase as with all dimmers running to the same levels, and therefore did not record them.

20%
Phase	Watts	VA	VAR	TPF	DPF
A	77.78	238.3	146.9	0.326	0.480
B	69.19	280.6	146.0	0.247	0.445
C	41.92	227.5	140.6	0.184	0.312

35%
Phase	Watts	VA	VAR	TPF	DPF
A	138.4	330.8	204.4	0.418	0.570
B	142.1	363.6	196.9	0.391	0.558
C	105.5	317.4	198.0	0.332	0.487

50%
Phase	Watts	VA	VAR	TPF	DPF
A	229.7	419.3	244.7	0.548	0.680
B	238.3	439.9	228.7	0.542	0.713
C	198.2	399.4	236.9	0.496	0.641

75%
Phase	Watts	VA	VAR	TPF	DPF
A	384.5	520.5	255.4	0.739	0.830
B	394.0	527.5	226.9	0.747	0.866
C	353.0	492.3	244.3	0.717	0.822

100%
Phase	Watts	VA	VAR	TPF	DPF
A	557.0	601.4	165.9	0.926	0.958
B	567.1	602.0	116.3	0.942	0.980
C	526.2	568.8	149.7	0.925	0.962

And here are a couple of pics from the meter.

Now we do have this still setup so we can provide other data if desired including phasors, harmonics graphs, etc. It's a nice meter and fun to play with. And why do we have it? Well, from time to time we run into odd power issues on job sites so we decided to station one meter here and one in the UK. We have them packaged with instructions and can leave them in place for a period of time to even gather anomolies and glitches. Then, people on site can email us the files and we can analyze them here. Technology is cool.

Ok, so how are we feeling about the data?

David

Excellent! It might be nice to add the data for THD-sub-I, just so we can all make that harmonic current correlation with the PF numbers.

ST

[someguy98457]

Thanks! Also not to go one question to far, but what happens with a sine wave dimmers?

Edit:
Can anyone explain why the switch causes the voltage and amperage to be out of phase? And also why at 100% does there still seems to be a reactive power load? If (in theory) your not chopping the sine wave doesn't that mean part of the cause of the var is else where? Or is it just close enough that it doesn't matter?

[STEVETERRY]

Thanks! Also not to go one question to far, but what happens with a sine wave dimmers?

Edit:
Can anyone explain why the switch causes the voltage and amperage to be out of phase? And also why at 100% does there still seems to be a reactive power load? If (in theory) your not chopping the sine wave doesn't that mean part of the cause of the var is else where? Or is it just close enough that it doesn't matter?

Typical phase control dimmers cannot turn completely on, so there is always a few microseconds of zero-crossing dead-time. This creates a slightly non-sinusoidal current waveform, which accounts for the PF of less than 1 when the dimmer is as close to full as it can get.

ST

[JD]

Thanks! Also not to go one question to far, but what happens with a sine wave dimmers?

Sine wave dimmers work by sectioning the waveform into many slices at a high frequency, much like meat slicer does in the deli. The output sections (or slices) are evenly spread across the waveform so that the output waveform still resembles a sine wave. Because the peak of the flowing current is not shifted towards the end of the waveform as it is in phase chop dimmers, the sine wave dimmer has a much higher power factor that does not change with the dimmer setting.
Sine wave dimmers also get rid of a few other problems, most notably, no triplen harmonics. Also, because there is not one BIG chop, RF harmonic issues are not a problem either. From a power standpoint, the whole thing is almost as clean as an autotransformer! ... Only one problem left. Price.