Jump to content

Talk:Power factor: Difference between revisions

Page contents not supported in other languages.
From Wikipedia, the free encyclopedia
Browse history interactively
← Previous edit
Content deleted Content added
VisualWikitext
m Reverted 1 edit by 103.89.26.28 (talk) to last revision by Qwerfjkl (bot)
 
(21 intermediate revisions by 10 users not shown)
Line 1: Line 1:
{{Talk header}}
{{Talk header}}
{{WikiProject banner shell|1=
{{WikiProject banner shell|class=B|
{{WikiProject Electrical engineering |class=B |importance=mid}}
{{WikiProject Electrical engineering |importance=mid}}
{{WikiProject Energy |class=B |importance=Low}}
{{WikiProject Energy |importance=Low}}
{{WikiProject Engineering |class=B |importance=Low}}
{{WikiProject Engineering |importance=Low}}
}}
}}
<!--
<!--
Line 23: Line 23:
a approx value of power factor which is acceptable in no energy losses <!-- Template:Unsigned IP --><small class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/115.248.112.54|115.248.112.54]] ([[User talk:115.248.112.54#top|talk]]) 13:33, 24 October 2017</small>
a approx value of power factor which is acceptable in no energy losses <!-- Template:Unsigned IP --><small class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/115.248.112.54|115.248.112.54]] ([[User talk:115.248.112.54#top|talk]]) 13:33, 24 October 2017</small>


== not understandable ==
== Problems with first two plot figures ==


This article doesn't make understandable what this power factor means or is supposed to be. It seems to indicate that "power" (whatever that means) somehow magically disappears because more current is being drawn from a supply than the device connected to the power supply receives.
On the currently-first plot figure, the caption includes the statement "The blue line shows all the power is stored temporarily in the load during the first quarter cycle and returned to the grid during the second quarter cycle,"


In this case, I'm looking at a power meter connected to a Dell R320 server with 2x350W PSUs connected to a 230V supply, and the power meter says the power factor is 36 while the server is turned off. What the hell is that supposed to tell me? This article doesn't answer the question at all. <!-- Template:Unsigned IP --><small class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/2A09:8E40:352B:D900:D16B:872B:FFD5:6B7D|2A09:8E40:352B:D900:D16B:872B:FFD5:6B7D]] ([[User talk:2A09:8E40:352B:D900:D16B:872B:FFD5:6B7D#top|talk]]) 05:01, 30 April 2022 (UTC)</small> <!--Autosigned by SineBot-->
This statement doesn't seem to make sense.


The next question is why do they make PSUs that have such a low power factor? Do the PSUs they put into servers suck?
First, I'm pretty sure those "quarter"s should be "half"s, referring to the feature that the dark blue (instantaneous) Power curve is positive in the first half-cycle, and negative in the second half-cycle.


:Sorry, this is not a question and answer forum. Try Quora. [[User:Constant314|Constant<b style="color: #4400bb;">''314''</b>]] ([[User talk:Constant314|talk]]) 05:24, 30 April 2022 (UTC)
Next, Power is rate-of-flow of energy (Energy/second) and is not something that can be "stored". What can be stored in the load is Energy. The negative portions of the blue Power curve mean negative flow-rate-of-energy, indicating the direction of (positive) energy flow is from load to grid.
::What part of "the power factor of an AC power system is defined as the ratio of the real power absorbed by the load to the apparent power flowing in the circuit" is giving trouble? And "real power" and "apparent power" have links, in case those are troublesome. I admit, the article has been improved so much that it's nearly unreadable, but this one sentence seems to be still ok ( ignore the crap about "closed intervals", that's just Wikiwanking) Why are you measuring the power factor of something that's turned off? What did you expect to do with the measurement that you made? --[[User:Wtshymanski|Wtshymanski]] ([[User talk:Wtshymanski|talk]]) 04:11, 31 May 2022 (UTC)


== Improved, but edits still required. ==
So I think the statement would be better as:


Of course this isn't a question and answer forum, as pointed out, but the topic must correctly answer the question of precisely what the topic is, and go beyond dictionary level.
The dark blue "Power" curve shows that, during the first half cycle, energy flows from grid to load. Then during the second half cycle, energy, that was stored in the load, flows back to the grid.


If "time invariance" is a present factor in determination of the accuracy of the calculation, it must be mentioned as such. In fact, no specification of time frames are present. RMS is barely mentioned. Where multiple waves exist, are offset, and aren't even sinusoidal, time frames must of course be measured, calculated or specified!!! If power factor is calculated on a per-cycle basis, which cycle is it? If it is NOT calculated on a per-cycle basis, what is the averaging basis?
There is a similar problem with the wording of the caption for the second figure. [[User:Gwideman|Gwideman]] ([[User talk:Gwideman|talk]]) 18:35, 3 November 2020 (UTC)


For some reason certain remarks ("the ratio of real power to apparent power") still exist over and over, but not in a problem / solution / proof format or presentation. In fact this wiki presently shows it is a collection of multiple, separate (and slightly conflicting!), pieces by multiple authors.
::The phrases "stored power" (instead of "stored energy") and "absorbed power" (instead of "absorbed energy") are unfortunately used all the time! Just like "current flow" (which is redundant, instead of "charge flow"), "flow of current" (instead of "flow of charge"), "power flow" (which is redundant, instead of "energy flow"), "flow of power" (instead of "flow of energy"), "AC voltage" (which is misleading, instead of just "AV" or "alternating voltage), "conventional current flows from positive to negative" (which isn't always true, for example inside a source that is supplying energy, or inside an inductor that is releasing energy from its magnetic field), "to charge a capacitor" (which is misleading, instead of "to charge the capacitor plates"), "to charge a battery" (which is misleading, instead of "to energize a battery"), "electromotive force (EMF)" (which is misleading because it is a voltage, not a force), and "magnetomotive force (MMF)" (which is misleading because it is a current, not a force), they're misleading/wrong/redundant. --[[User:Alej27|Alej27]] ([[User talk:Alej27|talk]]) 05:38, 4 November 2020 (UTC)


I hold no degrees, only some licenses which required some schooling, so I don't speak, and can't contribute, on the level of the main contributors here. I don't feel comfortable or capable of tackling the needed editing at this point. I'd call on the authors to do a bit of that. [[User:Tranzz4md|Tranzz4md]] ([[User talk:Tranzz4md|talk]]) 18:03, 28 August 2022 (UTC)
::: Well I'm not sure if you're saying that these misnomers are so common we should just accept them, or if Wikipedia should lead the charge to clean up technical language. I would lean toward the latter, though the most important criterion is for articles to be understandable to the largest number of readers. Almost anyone reading about "power" should understand that it refers to the time rate of energy flow, so introducing the proper term shouldn't have made it any more difficult to understand. However it would probably be best if at some point in the lede it specifically said that at least in passing. I'll let someone else edit the lede, but I just wanted to address what was a valid concern raised about the caption, but didn't look for every such possible correction where these misnomers are employed and will leave that for others. [[User:Interferometrist|Interferometrist]] ([[User talk:Interferometrist|talk]]) 14:51, 4 November 2020 (UTC)


:That is a valid complaint about this article. I will see if I can address it in the next few days. Also, most articles are a "collection of multiple, separate, pieces by multiple authors." [[User:Constant314|Constant<b style="color: #4400bb;">''314''</b>]] ([[User talk:Constant314|talk]]) 19:20, 28 August 2022 (UTC)
:::: I meant the latter: I'd love if Wikipedia promoted correct use of technical language. For the future reader, I'll explain why the phrases in my previous reply are misleading/wrong/redundant.
::I added the general case. I hope it answers the question. Everyone is invited to improve and edit. [[User:Constant314|Constant<b style="color: #4400bb;">''314''</b>]] ([[User talk:Constant314|talk]]) 20:52, 30 August 2022 (UTC)
::"...the higher currents increase the energy lost..." appears in the second paragraph. It would help me to know that this re-write is still correct: ...the higher currents increase ohmic heating (resistive loss)...". Energy is not "lost" to the electric field in a capacitor, or magnetic field in a motor. It's lost because efficiencies fall and stuff gets hot when I and V are not in phase.
::Before arriving at this Wikipedia article, I did consult Quora as suggested above. Quora now seems to count ChatGPT among its experts. After a bit of prompting, Mr GPT came back with "I apologize..." and agreed that "...it is accurate to state that a low power factor '''inevitably '''increases ohmic heating in electrical systems. Thank you for pointing out the ambiguity." (Emphasis mine.)
::If ChatGPT and I are correct, that 2nd paragraph might be revised slightly. I'm not all that confident in either of us (me and Mr GPT) so I'm not going to change anything.[[User:Captain Puget|Captain Puget]] ([[User talk:Captain Puget|talk]]) 18:43, 28 October 2023 (UTC)
:::Neither Quora nor ChatGPT are reliable sources. [[User:Constant314|<b style="color: #4400bb;">''Constant314''</b>]] ([[User talk:Constant314|talk]]) 20:16, 28 October 2023 (UTC)
:::The second paragraph looks correct to me. [[User:Constant314|<b style="color: #4400bb;">''Constant314''</b>]] ([[User talk:Constant314|talk]]) 23:15, 28 October 2023 (UTC)
:::I am neither claiming that Quora or ChatGPT is a valid source of anything, nor am I saying that paragraph is incorrect. I am asking if the loss is due to ohmic heating (which I believe to be the case), and not something else (I cannot imagine what that might be). Being explicit about the loss mechanism would seem a useful addition. [[User:Captain Puget|Captain Puget]] ([[User talk:Captain Puget|talk]]) 20:32, 30 October 2023 (UTC)
::::Yes, the loss is ohmic heating of the wires in that bring the electrical energy to the load. [[User:Constant314|<b style="color: #4400bb;">''Constant314''</b>]] ([[User talk:Constant314|talk]]) 20:36, 30 October 2023 (UTC)


== When was Power Factor first understood/detected/measured? ==
:::: * '''Electromotive force (EMF) and magnetomotive force (MMF) are not forces'''. In physics, ''[[Force|force]]'' is defined rigorously, and [[Electromotive force|EMF]] and [[Magnetomotive force|MMF]] aren't forces in this sense. EMF is a type of voltage, measured in volts; MMF is somewhat a type of current, measured in ampere-turns; force is measured in newtons. The textbook ''University Physics with Modern Physics, volume 2'' (12th edition) by Young, Freedman, Sears, and Zemansky, makes this observation on page 857: “The influence that makes current flow from lower to higher potential is called '''electromotive force''' (abbreviated '''emf''' and pronounced "ee-em-eff"). This is a poor term because emf is not a force but an energy-per-unit-charge quantity, like potential.”


It would be useful for the article to discuss the origins and "finding/discovery" of Power Factor. It might also be worth including in this Power Factor topic a write up of how scam companies use Power Factor to sell devices claimed to reduce your residential electric bill by up to 50% with a $40 device that contains nothing more than a less-than-$1 capacitor, and a less-than-$1 green LED in a $2 plastic housing that plugs-in to an electrical outlet. [[Special:Contributions/2601:648:8100:C83:55A8:670F:C635:3E13|2601:648:8100:C83:55A8:670F:C635:3E13]] ([[User talk:2601:648:8100:C83:55A8:670F:C635:3E13|talk]]) 20:12, 24 April 2023 (UTC)
:::: * '''Conventional current doesn't always flow from positive to negative, or equivalently, real current doesn't always flow from negative to positive'''. It's common to say that (conventional) current flows from positive to negative. But that's in general not true, even if we're talking about basic devices. That phrase is incomplete because they're not specifying ''in which device'' conventional current flows from positive to negative. For example, in a battery supplying energy, conventional current flows from negative to positive. In an inductor supplying energy previously stored in its magnetic field, conventional current flows negative to positive. I showed/proved this with GIFs and explained in more details in [https://www.quora.com/Does-current-flow-from-positive-to-negative-or-the-other-way-around/answer/Alejandro-Nava-2 this answer on Quora] (I hope that just by sharing that link, this reply isn't considered as self-promotion or spam.)

:::: * '''''Flow of current'' and ''current flow'' are redundant phrases; we should say ''flow of charge'' and ''charge flow'''''. To support my point, I'll quote page 571 of the textbook ''College Physics, volume 2'' (8th edition) by Raymond Serway, Chris Vuille, and Jerry Faughn, in which they say: “The phrases ''flow of current'' and ''current flow'' are commonly used, but here the word ''flow'' is redundant because current is already defined as a flow (of charge). Avoid this construction!”

:::: * '''''Flow of power'' and ''power flow'' are redundant phrases; we should say ''flow of energy'' and ''energy flow'''''. For the same reason as why ''flow of current'' is redundant, ''flow of power'' is too. Both [[Electric current|instantaneous current]] and [[Power (physics)|instantaneous power]] are defined as rates, and rates don't flow. Now, many electric power engineers will disagree with me on this, probably because in one-line diagrams (whether in power systems analysis or in distribution systems design) used in [[Power-flow study|power flow studies]] (also known as ''load flow studies''), it is common to show the direction of flow of active power and reactive power (the software ETAP is one example), so it indeed looks like active power and reactive power flow throughout the system, but this is redundant. First of all, what is active power and reactive power? Active power is another name for ''average power'', so, instead of saying ''active power flows from this bus to this other bus'', we should say, ''on average, energy flows from this bus to this other bus''. Regarding reactive power, this is a little trickier, so I won't address it in this reply. You can read [https://www.quora.com/Why-do-electric-power-engineers-keep-confusing-power-with-energy-They-usually-say-power-flows-which-is-redundant-because-power-is-already-a-flow-instead-of-energy-flows/answer/William-Beaty this answer on Quora] that explains why the previous phrases are redundant.

:::: * '''A device doesn't consume or absorb power, its power is the average rate at which it is using or delivering energy, respectively''' (I say “average” because ''power'' usually means the active/real/average power).

:::: * '''Batteries are not charged, they're energized''', assuming ''to charge'' means ''to gain/lose net electric charge''. In this video (https://www.youtube .com/watch?v=cPQbkTkGsnI) (join the link), a physicist named Nick Lucid criticizes the phrase “to charge a battery”. It is misleading because the battery doesn’t lose or gain a ''net'' charge when it is used or recharged, it only loses or gains energy. He suggests another phrase: “to energize a battery”.

:::: * '''Capacitors are not charged, but their plates are'''. In [https://electronics.stackexchange.com/a/98398/209934 this answer on Stack Exchange], a person (maybe an electrical or electronics engineer) named Phil Frost, at around the fourth paragraph, criticizes the phrase “the charge of a capacitor” or “to charge a capacitor”. It is misleading because a “charged” capacitor ''as a whole'' has no net charge, because the plates have equal but opposite charge. What is true, is that the ''individual plates'' indeed store charge. So we should use another phrase: “the charge of capacitor plates” or “to charge the capacitor plates”. Nick Lucid agrees with this fact (https://www.youtube .com/watch?v=cPQbkTkGsnI&lc=UgyejVM0i19bF_2ufWR4AaABAg).

:::: * '''''AC voltage'' means ''alternating current voltage'', which is non-sense; we should say ''AV'' (''alternating voltage'')'''. It's common to say “this outlet is 120 V AC”. I understand this phrase, but it is redundant. If we substitute “AC" for what it stands for, we get “this outlet is 120 V alternating current”. Well, not necessarily the current is alternating; for example if you plug in a charger (or rather, energizer?), the current won't be alternating direction, so we shouldn't call it ''AC'', however the voltage is still alternating. So we should say “this outlet is 120 V AV”, or simply “this outlet is 120 AV”.

:::: There're other misnomers, like calling the AC-DC adapter of a phone or laptop charger (energizer?) as a ''transformer''. It is wrong because the adapter not only contains a transformer, but also a bridge diode rectifier, capacitors for filtering, and a voltage regulator. Anyways, they should be fixed. --[[User:Alej27|Alej27]] ([[User talk:Alej27|talk]]) 01:30, 5 November 2020 (UTC)

:::::Look, that's all very interesting but has to do with linguistics and I cannot agree on changing the terminology in this (or other) page for the reasons given. ''Redundancy'' is common in language and shouldn't matter when it couldn't possibly be misunderstood by the reader. For instance, "AC current" is obviously redundant but can mean only one thing. And AC voltage is equally unambiguous unless you don't know that alternating current and voltage almost always go together. Saying the "wind blows" is equally redundant, you should say the "air blows" but this would never be misunderstood by anyone who knows that wind involves the blowing of air. The original objection, which I corrected, had to do with using the WRONG word (power instead of energy) in a generic sentence, but ''terms'' which are unambiguous and don't cause confusion needn't be changed (especially when it involves, for instance, two different terms for alternating voltage/current).
:::::But this is an interesting list, and you are free to create a new page called "Physics terms which are misnomers" or whatever, and you already have enough citations for it. Good luck! [[User:Interferometrist|Interferometrist]] ([[User talk:Interferometrist|talk]]) 19:23, 5 November 2020 (UTC)
::::::I agree with [[User:Interferometrist|Interferometrist]]. Articles should use common language constructs. [[User:Constant314|Constant314]] ([[User talk:Constant314|talk]]) 19:26, 5 November 2020 (UTC)

:::::This is almost pure pedantry, and much is incorrect.

:::::Current is ''not'' a flow a charge. It is the ''rate of flow'' of charge (and is defined as such), to the point that one ampere is defined as the flow of one coulomb ''per second''.

:::::Flow of current or current flow is the accepted terminology to describe electrical charge flowing from one place another (specifically quantising the rate of that flow).

:::::Similarly: power is not a flow of energy but the ''rate of flow'' of energy (and is defined as such), to the point that one watt is defined as the flow of one joule ''per second''.

:::::Similarly: Flow of power is the accepted terminology to describe any form of energy flowing from one place another (specifically quantising the rate of that flow).

:::::MMF and EMF may not be forces in the mechanical sense per se, but they are magnetic and electrical forces respectively inasmuch as they force something to move from one place to another (in the latter case charge).

:::::Electron flow always flows from a more negative place to a more positive place if there is no EMF forcing it to do otherwise. Conventional current flow is only positive to negative because Andre Marie-Ampere arbitrarily decided it should be so (the electron being unknown at the time).

:::::Capacitors' plates are not charged. If you have seen a demonstration of a charged Leyden jar being dismantled and all the parts handled by the earthed demonstrator and then reassembled. The fact that the rebuilt jar can then be be discharged is clear evidence that the plates do not store the charge. Pedantically: the plates do store a very small charge but it is insignificant.

:::::Capacitors are charged in that they are capable of holding a charge. Capacitance is defined as 'the ability of a body to hold an electrical charge'.

:::::Batteries are similarly charged because they too will hold a charge (even though internally they convert the energy contained in that charge to chemical energy). Lithium-ion batteries behave almost exactly like a capacitor subject to some limitations. Indeed, over their useful charge range they behave more like capacitors than some real capacitors do.

:::::AC volts and AC current, and their DC counterparts, are standard nomenclature and universally understood (and even Thomas Edison and George Westinghouse used the terms to differentiate their respective electrical systems). Pedantically, it is not strictly correct, but encyclopaedias are written by what is universally understood not on what is pedantically correct. Further the terminology is simplicity itself to source. Almost any multi-meter is marked 'DCV', 'ACV', 'DCA' and (if you have a posh meter) ACA. [[Special:Contributions/86.142.79.215|86.142.79.215]] ([[User talk:86.142.79.215|talk]]) 18:34, 2 December 2020 (UTC)

== Shouldn't we clarify that power factor is usually never expressed as a negative number? ==

I understand why power factor can be negative. Just like why average/real/active power can be negative. However, we don't usually say "this generator absorbs -20 kW" but instead "this generator supplies +20 kW". Similarly, we don't usually say the power factor of a generator is negative, even though under normal circumstantes its absorbed active power is negative (i.e. its generated active power is positive), which implies PF < 0 since PF = P/S where S > 0. --[[User:Alej27|Alej27]] ([[User talk:Alej27|talk]]) 16:31, 4 November 2020 (UTC)

:Listen this issue was already debated, extensively (to the point I never read most of it!) on an ''archived'' talk page here: [[https://en.wikipedia.org/wiki/Talk:Power_factor/Archive_2#Negative_Power_Factor?]] - [[User:Interferometrist|Interferometrist]] ([[User talk:Interferometrist|talk]]) 19:33, 5 November 2020 (UTC)

::Ups, I didn't know about that long discussion. --[[User:Alej27|Alej27]] ([[User talk:Alej27|talk]]) 19:42, 5 November 2020 (UTC)

:Whilst what you say is entirely correct for an electrical device that either exclusively generates power or absorbs power, you need to consider situations where power can either be absorbed or generated. The obvious example of this is a consumer who has installed solar cells. At night, such a consumer absorbs power from the grid which is usually considered positive power consumption (and the electricity meter records this positive power as an increasing display of energy consumption). However: during a sunny summer's day, the solar cells may well generate more power than the consumer is actually using. This surplus power is fed back to the grid and is considered to be negative power (in that it flows the other way). So much so that the electric meter now logs this negative power by running backwards. That is: the meter records this negative power with a ''decrease'' of recorded energy supplied. [[Special:Contributions/86.142.79.215|86.142.79.215]] ([[User talk:86.142.79.215|talk]]) 12:09, 3 December 2020 (UTC)

== Specifying the circuits being discussed are LTI (of constant parameters) is not a leap too far ==

Anonymous user of IP 86.129.19.88 reverted [https://en.wikipedia.org/enwiki/w/index.php?title=Power_factor&oldid=1028283002 my edit] to [https://en.wikipedia.org/enwiki/w/index.php?title=Power_factor&oldid=1029539014 this version]. Their reason:

"This concept is a leap to far for an article of this nature. It only serves to obfuscate the issue being discussed. Simplicity is always better."

In my edit, I clarified that it is linear time-invariant circuits (and not any linear circuit) that don't change the shape of applied volage in the resulting current. In other words, I fixed a mistake. There are linear circuits that produce harmonics: linear time-variant circuits. However, the user reverted my edit, making the article wrong again.

In my edit, I didn't go into much details of what was a time-invariant circuit. Instead, I just changed the words "linear" for "linear time-invariant", and I even added a short example of such a circuit: a circuit whose R, L and C are constants.

"It only serves to obfuscate the issue being discussed." // I don't think so. It serves to clarify what is being discussed: LTI circuits, not just any linear circuit.

"Simplicity is always better." // Yes, simplicity is better, as long as it is correct, which was not the case. So that's why I corrected the article.

Don't you prefer to have a specific but correct explanation than a shorter but wrong explanation? --[[User:Alej27|Alej27]] ([[User talk:Alej27|talk]]) 20:17, 20 June 2021 (UTC)

:In ordinary parlance, a resistor, capacitor, or inductor (or a linear amplifier) without further qualification is considered linear and time-invariant EVEN THOUGH there is always SOME voltage or current that can overload or destroy it, but that doesn't change its basic character. A VARIABLE R/C/L is considered to be linear on the timescale of the signal even though it changes when someone turns the knob. Yes, if a 100Hz signal is processed by an LTI circuit while someone turns the knob on millisecond time scales then you get new frequencies, but that doesn't justify changing our normal way of speaking. If the R/C/L is dependent on voltage or current then it obviously isn't linear, but you have different names for such components. There is always non-ideal behaviour that needn't be pointed out when it isn't dominant. Otherwise we could never talk about a resistor or capacitor without specifying its stray inductance, leakage, temperature dependence etc. These are a higher level of detail that shouldn't be introduced into the basic explanations. [[User:Interferometrist|Interferometrist]] ([[User talk:Interferometrist|talk]]) 21:10, 2 July 2021 (UTC)

:[https://en.wikipedia.org/enwiki/w/index.php?title=Power_factor&type=revision&diff=1029539014&oldid=1028283002 Here's the diff in dispute]. {{u|Alej27}}, I've added a link to [[Linear time-invariant system]] to help readers through this [[WP:JARGON|terminology]] you've introduced. I think it is a reasonable assumption that electrical parameters for the R, L and C devices are constant so stating that qualification is unnecessary. ~[[User:Kvng|Kvng]] ([[User talk:Kvng|talk]]) 14:10, 5 July 2021 (UTC)

:: I think the [https://en.m.wikipedia.org/enwiki/w/index.php?title=Power_factor&oldid=1032095120 current version] as edited by {{u|Kvng}} is good. It doesn't say the R/L/C are constants (so I think it is in agreement with {{u|Interferometrist}}), but it also clarifies the ''wrong'' statement that linear circuits ''always'' produce sinusoidal outputs of same frequency to sinusoidal inputs (it's false, they don't, ''e.g.'' linear time-variant circuits). --[[User:Alej27|Alej27]] ([[User talk:Alej27|talk]]) 17:26, 5 July 2021 (UTC)

::: Thinking back, long ago to my university lectures, it seems that in each class that the professor would say, once, near the beginning of the semester, that the math applied to linear time-invariant circuits. He did not elaborate. He was being rigorous, but not tedious. One time, I asked if a certain result always applied and the professor replied, “yes, for linear time-invariant circuits.” I suppose hearing it often enough drummed it into my consciousness. I think that is what we should do in this article. Mention it once, with a wiki-link, without elaboration and move on. [[User:Constant314|Constant<b style="color: #1100cc;">''314''</b>]] ([[User talk:Constant314|talk]]) 18:06, 5 July 2021 (UTC)

:::: {{ping|Constant314}} So in section ''Linear time-invariant circuits'' we should say something like "Linear time-invariant circuits ''(referred to simply as linear circuits for the rest of this article)'', for example, circuits consisting of combinations of resistors, inductors and capacitors have a sinusoidal response to the sinusoidal line voltage"? That'd be a good idea, since in the current version of the article, loads are still called as linear even though they are actually linear time-invariant (e.g. the power triangle doesn't hold true for linear time-variant loads). --[[User:Alej27|Alej27]] ([[User talk:Alej27|talk]]) 07:54, 21 July 2021 (UTC)←

::::: Sure, put in that parenthetical remark if it helps. When you don't specify otherwise, time-invariance is almost always assumed. You have to go to a lot of trouble to make an actual physical system that is not time-invariant, and even further to find an actual use for it. And in cases when something is labelled non-time-variant (like the "examples" I removed from the to-be-deleted "time-variant" page), there isn't any clear distinction between saying that and saying that it's a non-linear system with two inputs. So I don't know about any "time-varying loads", but perhaps you're referring to a motor under differing back torque, in which case you could just as well call that torque an additional input in a nonlinear system. So although "time-invariant" is a useful and correct qualifier, it hardly ever needs to be pointed out when you just say "linear system" or linear component. [[User:Interferometrist|Interferometrist]] ([[User talk:Interferometrist|talk]]) 15:34, 21 July 2021 (UTC)

::::: I'm good with that. [[User:Constant314|Constant<b style="color: #1100cc;">''314''</b>]] ([[User talk:Constant314|talk]]) 20:40, 21 July 2021 (UTC)

== Typos ==

Seems like every page ought to have a section for just typographical errors. Anyway, this
"''The power factor...or equivalently the angle by which the voltage''"
seems to be missing a word. It should be "''...equivalently the '''sine''' of the angle...''".
The whole sentence seems unnecessarily long, though. I would suggest
''The power factor '''is''' the cosine of the angle θ ...''
[[User:Captain Puget|Captain Puget]] ([[User talk:Captain Puget|talk]]) 22:41, 19 November 2021 (UTC)
:[[WP:BOLD|Go for it!]] You might as well fix the article as comment on it on the talk page, especially for stuff like this. --[[User:Wtshymanski|Wtshymanski]] ([[User talk:Wtshymanski|talk]]) 21:57, 22 November 2021 (UTC)
::No. Because it is the same angle. It is still the phase angle between current and voltage whichever way around you express it. Why we actually need to express it the other way around is another matter. [[Special:Contributions/86.188.36.150|86.188.36.150]] ([[User talk:86.188.36.150|talk]]) 18:05, 6 December 2021 (UTC)

== not understandable ==

This article doesn't make understandable what this power factor means or is supposed to be. It seems to indicate that "power" (whatever that means) somehow magically disappears because more current is being drawn from a supply than the device connected to the power supply receives.


:Scam avoidance and consumer warnings are outside the charter of Wikipedia. [[User:Constant314|<b style="color: #4400bb;">''Constant314''</b>]] ([[User talk:Constant314|talk]]) 20:33, 24 April 2023 (UTC)
In this case, I'm looking at a power meter connected to a Dell R320 server with 2x350W PSUs connected to a 230V supply, and the power meter says the power factor is 36 while the server is turned off. What the hell is that supposed to tell me? This article doesn't answer the question at all.
::Would it not accomplish much the same thing to say somewhere that "unless a residential consumer is running a 100hp electric motor, it is unlikely that they would have a power factor small enough to impact the grid or their electric bill." [[User:Captain Puget|Captain Puget]] ([[User talk:Captain Puget|talk]]) 19:03, 28 October 2023 (UTC)
:::You would need a reliable source and it probably would not be notable. [[User:Constant314|<b style="color: #4400bb;">''Constant314''</b>]] ([[User talk:Constant314|talk]]) 20:14, 28 October 2023 (UTC)

Latest revision as of 11:45, 22 August 2024

what is the approx value of power factor which is maintain by factory

[edit]

a approx value of power factor which is acceptable in no energy losses — Preceding unsigned comment added by 115.248.112.54 (talk) 13:33, 24 October 2017

not understandable

[edit]

This article doesn't make understandable what this power factor means or is supposed to be. It seems to indicate that "power" (whatever that means) somehow magically disappears because more current is being drawn from a supply than the device connected to the power supply receives.

In this case, I'm looking at a power meter connected to a Dell R320 server with 2x350W PSUs connected to a 230V supply, and the power meter says the power factor is 36 while the server is turned off. What the hell is that supposed to tell me? This article doesn't answer the question at all. — Preceding unsigned comment added by 2A09:8E40:352B:D900:D16B:872B:FFD5:6B7D (talk) 05:01, 30 April 2022 (UTC)[reply]

The next question is why do they make PSUs that have such a low power factor? Do the PSUs they put into servers suck?

Sorry, this is not a question and answer forum. Try Quora. Constant314 (talk) 05:24, 30 April 2022 (UTC)[reply]
What part of "the power factor of an AC power system is defined as the ratio of the real power absorbed by the load to the apparent power flowing in the circuit" is giving trouble? And "real power" and "apparent power" have links, in case those are troublesome. I admit, the article has been improved so much that it's nearly unreadable, but this one sentence seems to be still ok ( ignore the crap about "closed intervals", that's just Wikiwanking) Why are you measuring the power factor of something that's turned off? What did you expect to do with the measurement that you made? --Wtshymanski (talk) 04:11, 31 May 2022 (UTC)[reply]

Improved, but edits still required.

[edit]

Of course this isn't a question and answer forum, as pointed out, but the topic must correctly answer the question of precisely what the topic is, and go beyond dictionary level.

If "time invariance" is a present factor in determination of the accuracy of the calculation, it must be mentioned as such. In fact, no specification of time frames are present. RMS is barely mentioned. Where multiple waves exist, are offset, and aren't even sinusoidal, time frames must of course be measured, calculated or specified!!! If power factor is calculated on a per-cycle basis, which cycle is it? If it is NOT calculated on a per-cycle basis, what is the averaging basis?

For some reason certain remarks ("the ratio of real power to apparent power") still exist over and over, but not in a problem / solution / proof format or presentation. In fact this wiki presently shows it is a collection of multiple, separate (and slightly conflicting!), pieces by multiple authors.

I hold no degrees, only some licenses which required some schooling, so I don't speak, and can't contribute, on the level of the main contributors here. I don't feel comfortable or capable of tackling the needed editing at this point. I'd call on the authors to do a bit of that. Tranzz4md (talk) 18:03, 28 August 2022 (UTC)[reply]

That is a valid complaint about this article. I will see if I can address it in the next few days. Also, most articles are a "collection of multiple, separate, pieces by multiple authors." Constant314 (talk) 19:20, 28 August 2022 (UTC)[reply]
I added the general case. I hope it answers the question. Everyone is invited to improve and edit. Constant314 (talk) 20:52, 30 August 2022 (UTC)[reply]
"...the higher currents increase the energy lost..." appears in the second paragraph. It would help me to know that this re-write is still correct: ...the higher currents increase ohmic heating (resistive loss)...". Energy is not "lost" to the electric field in a capacitor, or magnetic field in a motor. It's lost because efficiencies fall and stuff gets hot when I and V are not in phase.
Before arriving at this Wikipedia article, I did consult Quora as suggested above. Quora now seems to count ChatGPT among its experts. After a bit of prompting, Mr GPT came back with "I apologize..." and agreed that "...it is accurate to state that a low power factor inevitably increases ohmic heating in electrical systems. Thank you for pointing out the ambiguity." (Emphasis mine.)
If ChatGPT and I are correct, that 2nd paragraph might be revised slightly. I'm not all that confident in either of us (me and Mr GPT) so I'm not going to change anything.Captain Puget (talk) 18:43, 28 October 2023 (UTC)[reply]
Neither Quora nor ChatGPT are reliable sources. Constant314 (talk) 20:16, 28 October 2023 (UTC)[reply]
The second paragraph looks correct to me. Constant314 (talk) 23:15, 28 October 2023 (UTC)[reply]
I am neither claiming that Quora or ChatGPT is a valid source of anything, nor am I saying that paragraph is incorrect. I am asking if the loss is due to ohmic heating (which I believe to be the case), and not something else (I cannot imagine what that might be). Being explicit about the loss mechanism would seem a useful addition. Captain Puget (talk) 20:32, 30 October 2023 (UTC)[reply]
Yes, the loss is ohmic heating of the wires in that bring the electrical energy to the load. Constant314 (talk) 20:36, 30 October 2023 (UTC)[reply]

When was Power Factor first understood/detected/measured?

[edit]

It would be useful for the article to discuss the origins and "finding/discovery" of Power Factor. It might also be worth including in this Power Factor topic a write up of how scam companies use Power Factor to sell devices claimed to reduce your residential electric bill by up to 50% with a $40 device that contains nothing more than a less-than-$1 capacitor, and a less-than-$1 green LED in a $2 plastic housing that plugs-in to an electrical outlet. 2601:648:8100:C83:55A8:670F:C635:3E13 (talk) 20:12, 24 April 2023 (UTC)[reply]

Scam avoidance and consumer warnings are outside the charter of Wikipedia. Constant314 (talk) 20:33, 24 April 2023 (UTC)[reply]
Would it not accomplish much the same thing to say somewhere that "unless a residential consumer is running a 100hp electric motor, it is unlikely that they would have a power factor small enough to impact the grid or their electric bill." Captain Puget (talk) 19:03, 28 October 2023 (UTC)[reply]
You would need a reliable source and it probably would not be notable. Constant314 (talk) 20:14, 28 October 2023 (UTC)[reply]
Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=Talk:Power_factor&oldid=1241649021"