The Most Important Circuit for our Electrical Future?! (PFC) EB#55

[@RedHotFiat]

I used to work at a very large manufacturing facility that was built in the late 1960s. This place was so big it had it's own power substation. They had incredible milling machines to create large parts for aircraft. At some point they were experiencing a large lagging power factor issue and the utility was going to require them to pay for a major upgrade to the power lines to the facility. One of their electrical engineers said hold on. He designed a system to use synchronous motors to create a leading power factor to correct the problem. He used these motors to power air compressors for the facility since they used a lot of compressed air. In 1980 we installed a 5000v 500 horsepower synchronous motor. It was the 3rd compressor in that building. Since that time a lot of the electrical loads have been changing. The lighting all changed from fluorescent to high pressure sodium in 1982. By 1990 we were replacing those with metal halide. Now those have been replaced with LEDs. The milling machines are all going to variable frequency drives. I retired in 2012 so I don't see what's going on there anymore.

[@DrRedstone172]

now it probably has leading power factor in the off duty hours, due to parasitic cable capacitance

[@RedHotFiat]

@@DrRedstone172 They don't run the synchronous motors all the time. They only need compressed air when the machinery is running. It's also my understanding they can change the exciter voltage to change the lead, but I'm no expert.

[@DrRedstone172]

@@RedHotFiat i meant the capacitance in the cables

[@cods41]

​@RedHotFiat correct, they over excite the rotor which creates a leading power factor. When synchronous motors are used in this way they are called synchronous condensers. But since in your case, they were using them as both motors and condensers they would be considered some sort of hybrid. Now days there are more efficient methods of producing VARs.

[@anon_y_mousse]

@@RedHotFiat What kind of aircraft parts did they manufacture? Any jet turbine parts?

[@AnIdiotAboard_]

Its about time PFC was delt with. Harmonics are no joke. Im pleased to finally see this, given all the DC loads in our world now days.

[@greatscottlab]

Thanks for the feedback. I hope the video is worth the topic :-)

[@AnIdiotAboard_]

@@greatscottlab Id like to see Harmonic Distortion covered in general, and why PFC is now more important than ever, and the very real risks of doing nothing.

[@gregorymccoy6797]

This was a great topic. Thanks for a well+presented video.

[@greatscottlab]

Thank you very much for the feedback and support :-)

[@sicotronicypunto7460]

Btw, you can change the backroom color of the schematic sheet in altium (in propierties around the same area of paper size) so when you print it you don't waste as much ink ;)

[@EvillNooB]

@@adeijabari4291 easyEda uses white by default tho, while kiCad & many others use yellowish

[@diyemc7206]

PFCs are mandatory already! If your device is CE marked, it should have been tested to IEC 61000-3-2/-3-12. Exclusions for Harmonics are

[@thear1s]

That probably explains why it was so difficult for me to find a 12V PSU over 5A, because it'd require an expensive compensation circuit.

[@xelth]

The lamp has 20W and 4W goes for harmonics. But you need 100 pieces for the hall.

[@xelth]

You are right. I have now dismantled a cheap LED lamp from China, even there is a PFC built in.

[@xelth]

But the question remains... who makes 160kvar a month for me!!! If not LEDs, there are still about 15 cameras or forklift chargers from Jungheinrich from 2010...

[@seedney]

That explains why any laptop charger I have have PF around 0.48

[@JohnAudioTech]

Many good quality LED bulbs have PFC correction built in. It is mainly to allow them to work with existing dimmers, but at least keeps the harmonics on the mains down.

[@wojciechbajon]

Probably not. dimabble led has microcontroller, who decect how mant sinusoid us cut by triac.

[@TimPerfetto]

@@wojciechbajon Probably not. Many good quality LED bulbs has microcontroller. Who decect how mant triac harmonic mains down PFC

[@NightHound1337]

Most do not. The regulation governing low power bulbs has been made in cooperation with the bulb manufacturers. This means that PFC is only required at higher wattage than those most common. As the limit is lowered, so does the power of the bulbs. Currently I think it is around 15 W, which is why manufacturers do not make bulbs above 14 W.🤑🎉

[@TimPerfetto]

@@NightHound1337 Most do not. The limit is lowered governing low power only required at higher wattage then I think it is around 15w this means that the PFC is only those most common

[@monad_tcp]

@@NightHound1337 WTF Instead of having better products, we get capped ones

[@OpenSourcerers]

The fact that you have a relatively high number of subscribers gives me hope for the future.

[@greatscottlab]

Lots of people are interested in science. You just have to pack it up in an interesting video format ;-)

[@iamdarkyoshi]

@@greatscottlab It's not just the format, it's the attention to detail and the tangible examples. Your drawings are absolutely first class, I daresay you'd be able to outdraw most pen plotters!

[@Speeder84XL]

Nice! Funny detail that this video also really shows how distorted the mains voltage has become, because of this problem. It's very common for it to look just like in the video. The top of the sine wave get "clipped" (almost like an overdriven audio signal) because of voltage sag when all the AC to DC converters with smoothing capacitor and no PFC, draws current only in that part of the wave.

[@smeezekitty]

He may be using an isolation transformer which could distort the sinewave. Connecting and oscope directly to mains risks a short circuit

[@Speeder84XL]

@@smeezekitty True - if he uses such a transformer to power the load. It would probably be better to use it for powering the scope though. Then a much smaller and cheaper transformer could be used as well and any distortion like that shouldn't matter, since it's turned to DC before being used by the circuitry in the scope anyway. There are some small "pocket models" of scopes that can run on USB. I have one of those. They can measure mains stuff with no issue if powered from an insulated source like a power bank or cell phone charger. I could think a standard one powered by an insulation transformer would be similar. But maybe some scopes get noise issues if ground is left floating (and not the best for those who are concerned about safety, since if the scope has a grounded metal casing, it can go live during measurement - but as long as user/casing has no outer grund contact, it will do fine)

[@ericrawson2909]

​@@Speeder84XL No, the both the primary and secondary windings show the same distorted waveform. Furthermore, my local supply here in South Devon, England varies by a few volts all the time It appears to have a few superimposed frequencies in the range one to three Hz, which I believe are caused by different generators in the supply network interacting with each other. A big driver of this is the diminishing amount of heavy rotating generators as they are replaced by solar panels. There is also a lot of high frequency noise from invertors and switch mode power supplies. It's a mess! (Just building a stabilised power supply before I resume my tube amp experiments.)

[@hugegamer5988]

What? Mains rms voltage dropping? I just have a variable transformer and turn it up if the voltage sags. Problem solved! /s

[@Doktoreq]

Around 8:36 you didn't have to remove that rectifying bridge unless voltage would be higher than what it can handle. It would work fine just dropping voltage slightly giving you protection against reverse polarity.

[@deslomeslager]

I use those adapters on my (string of) solar panels. Works great! 230 Volt is more than enough. When the grid goes down, adapters help me to generate energy locally.

[@Conservator.]

I came here to comment the same.

[@duanerackham9567]

I remembered all this from engineering school. You explained it a lot better. I remember calculating all of it and not understanding where I'd ever use it. Funny enough I work at a large corporation now and use emails more than any engineering tools.

[@coin777]

it is funny

[@Harambe_]

Sounds like most engineering students I knew. Wonder why they needed to learn so much math to write emails. XD

[@jeffspaulding9834]

That's an easy trap to fall into. A lot of the business types focus on the things they understand - business development, proposals, project management - and forget that once you've gotten that nice, shiny contract someone has to do the technical work. There's definitely a place for technical-oriented engineers, but you have to push for that position. I did (I'm an integrator/system analyst, not an engineer, but it's similar), and now I only work on the type of stuff I want instead of writing documents and tracking lead times all day.

[@zwidewe2764]

​@Jeff Spaulding GREAT Enjoy your work! That's why I wanted to become an engineer. Unfortunately the business brains taking so much demand that only low time is left for engineering. I decided also not to be too far away from technology.

[@vojtechadame5860]

Great video! Also, it only remains to add, that some power supplies use passive PFC in form of a huge coil on an iron core. The coil opposes the fast current rises of the capacitor without drawing too much real power.

[@greatscottlab]

Interesting

[@analoghardwaretops3976]

Passive pfc's are ok for light loads..where the pcb/component area is not a constraint..since all components required are to function at i/p DC rectified ripple frequency 2×(50/60Hz) hence it becomes bulky although NO BULK CAPACITORS ARE USED.. ......typically single stage is most common a single stage is usually 3 diodes, 2 caps. & 1or 2 inductors ( but 2 & 3 stage are designed..3 stage design reduces p-p ripple to about 30%...also has higher ripple frequency. so dc is good.

[@analoghardwaretops3976]

Single stage passive pfc's had widespread use in C.FL.'s with ratings up to 20-25 W.

[@ogi22]

AAAAhhhhhh! so that's what that honking big ass coil is for in the power supply units!!!! 🤗thank you kind man for sharing your wisdom. And big thanks to Scott for lovely electronics lessons!

[@tjeulink]

​@@ogi22 thats not what they are used for most of the time

[@GhostsOfSparta]

Glad to see you got sponsership from Mouser!! I love your channel.

[@Rendraco79]

I just want to say this: This gifted kind of man, is really needed in every university and tech institute.

[@balloney2175]

I bet you, even professors can't afford to post in/on KZbin.

[@hvanmegen]

I wasted 20 years of my life paying my own electricity bills without knowing what PFC actually is and why it is important.. this is the first video I've seen that actually explains it so that I understand it. This german is an international treasure and should be honored somehow. The EU should give out grants for science and technology educators like this!

[@hotgluegunguy]

​@@hvanmegen As a private consumer, you only pay for the real power, so adding PFCs won't save you on the electricity bill. Your electricity provider will probably like you though.

[@PavolFilek]

But we need something to use,, e.g. PCB and SW for 2-phase BUCK, BOOST MPPT, or sinus 50 Hz 240 V / 40 AMPS inverter / HF or LF /

[@LabArlyn]

Finally you made an explanation video about PFC. 🍓 I had been wondering how does PFC work.

[@greatscottlab]

Hope you like it!

[@trevoro.9731]

Basically rectifier-> DC-DC converter with a transformer. You should not think of it as PFC or whatever sh*t, just a pwm variable input DC-DC converter, by modulating the frequency you can get a needed current "draw".. Or 2-channel DC-DC converter.

[@ianhill20101]

I used to work for a company installing pfc equipment in my local steel works on motor drives etc, we never used the dc method didnt even have pwm supplys back then we just got the the current and voltage close as we could for the induction motors to prrrr.

[@trevoro.9731]

@@ianhill20101 For consumer electronics AC/DC - DC converters with PWM regulation are more efficient. The older stabilizers back from 1970th are consuming extra power for their own operation.

[@user-td3yi1mq7p]

​@@trevoro.9731 What are you talking about? In the standard boost PFC, which I think is shown in the video, there is no transformer

[@adrianguerrero5769]

I’ve never heard of the foam to drink ratio analogy before until now. But it makes so much sense now. Thank you Great Scott !

[@analoghardwaretops3976]

Y.T. vids. with detailed PFC explaination show beer/ foam ratio analogy.

[@paulcollins8296]

HI, further to my previous post I have been told by the meter manufacturer that the sampling period for AC current is 100ms. If I understand correctly the cycle time for 50Hz is 20ms, therefore it looks like my meter measures my current use every 5 voltage cycles and assumes that the current waveform is sinusoidal. MY office uses many LED lights and other electronic devices and the current waveform is not sinusoidal, not symmetric and just a mass of spikes. It seems to me that there is almost zero chance that my electricity is being accurately metered.

[@AllAmericanBeaner68]

It had not occurred to me to consider harmonics with respect to power let alone an active power factor compensation system. Very interesting video as usual!

[@cappie2000]

Best explanation I heard about PFC my entire life.. I finally understand what it is!

[@Ale-bj7nd]

Not only because of LEDs, but with the increasing number of inverters, as a company we are starting to install neutral cables with bigger sections (it usually is half the phases section). Harmonics are starting to get at concerning levels in some places.

[@d614gakadoug9]

This issue became a big thing when computers first started hitting desktops in large office environments. There were instances of neutral cables actually getting hot enough to burn off their insulation. This is due to the fact that the narrow current pulses that result from simple rectification and capacitive filtering, as shown in the video, don't cancel in three-phase systems and instead almost 100% of the current would flow in the neutral contuctor - six non-overlapping pulses per cycle. A lot of this was blamed on the use of switched mode power supplies, but any capcitively filtered rectifier circuit is just about as bad. Iron core transformers do slightly knock down the current peaks due to leakage inductance, but not in a very useful way. It was mostly just the fact that switchers were used in most of the devices installed when use of electronics in offices exploded.

[@rdcabal]

​@@d614gakadoug9 newer computers use less power these days because the cpus are faster than a person needs

[@mohamedarshad6207]

Brillient stuff. Learning curve. Thks for putting it out

[@bhagathsivadasan7650]

The common household consists of lagging power factor due to at least there being a fridge, ceiling fans, exhaust fans or an AC all of which require reactive power to operate. The most simple way to deal with that is to connect a mains voltage rated capacitor of 1kvar or more as required parallel to the mains breaker. In most skyscraper/ big buildings it is mandatory to place an APFC Panel board to monitor and control power factor between -0.96 to +0.96

[@greatscottlab]

Thanks for the feedback. Good information about the skyscraper.

[@paparoysworkshop]

I always enjoy your videos and often learn new things. Thank you for the effort you put into creating these videos.

[@boristheengineer5160]

From what I've read the real problem with uncorrected electronic power supplies is the amount of third harmonic current drawn, as in a three phase system the neutral current is supposed to cancel but the 3rd harmonics add. One possible unfortunate unintended consequence is that with the power supply industry bragging about 0.98+ power factors in single phase equipment and crazy low harmonics it has caused a problem for the designers of multi-kilowatt systems. It is easy to get a simple three phase rectifier to about 0.85, maybe 0.9 I can't remember the exact figure by just levelling the current drawn and sometimes an inductor is enough, but getting above that to the levels claimed for single phase designs is significantly more complicated. As a result installations that should be three-phase input end up using multiple single phase modules instead. Hopefully they are properly spread across phases.

[@ReverendFlatus]

Nice fart at 44s.

[@greatscottlab]

;-)

[@osamashokry4524]

Things like these you shouldn't be talking about😅 Just ignore it

[@rdxdt]

I noticed too

[@patcherandpatch]

Hope you liked 😏

[@sylvester4207]

@@osamashokry4524 lol its funny though :)

[@Kaivalaginiviti]

Given the amount of DC devices these days maybe homes should include PFC'ed DC sockets as well as AC and have the bulky PFC circuit in the wall/at the fuse box? Then DC devices plug into DC sockets? How small can active PFC get? Is it acceptable to expect it with all DC devices in the future?

[@siberx4]

It's also worth mentioning that the "apparent power" of a device with poor power factor is *not* the power you pay for in a residential situation; you pay _only_ for the real power component. Power factor is a consideration and concern at the grid level, but will not meaningfully impact your own power bill. I say this mostly because there's a lot of scam products out there that claim they can save you tons of money on your electrical bill by correcting your home's power factor simply by plugging them into an outlet. Even if these devices _did_ correct your power factor (most don't do anything), they still wouldn't save you any measurable money, and their little LED will probably consume more power than they'd otherwise save!

[@matejrehak896]

Nice video. I can only note at 8:00 professionals don't put PCBs with grid voltage traces on a bare table. Professionals use distance bolts.

[@ljubomirculibrk4097]

Real profesionals use rubber mat whit spacers 😂

[@etherealrose2139]

Last I checked, wood is an excellent insulator. Who tf cares? Talk about picking nits

[@realms4219]

Highly recommend to use ATX power supplies for larger applications. They're tested, rated and certified for all the good stuff one needs/wants in a PSU.

[@farizfadillah7557]

@@saiv46 high power ATX12VO with separated DC2DC converter for another voltages (3v,5v,-5v,-12v) sounds good..

[@mikes2381]

​@@saiv46 If you're looking at using a consumer computer power supply for just one voltage, it probably isn't for a project that is on frequently at all. For these temporary projects, the extra useful but immediately unused voltages really aren't a concern. A 12VO PSU would then need subsequent voltage modulating circuitry. Like buck/boost converters. With a current standard ATX PSU, and DIY projects, you're pretty likely to have use for 3.3 VDC, and 5 VDC on top of the 12 VDC. Those other circuits add complexity outside of the PSU and are likely not as high quality and clean as the ones in an ATX PSU.

[@stalkerfromvoronezh4493]

Cheap ATX PSU very simple like this 12V PSU. They are no contains PFC.

[@superslash7254]

@@saiv46 Pray they never do. 12vo is going to be a nightmare of proprietary cabling on both the psu and mobo side of things as well as offloading an enormous amount of voltage switching to one of the most expensive and least reliable parts of your computer.

[@blackwidowrsa]

@@saiv46 because moving all the other power rails directly to the mobo you have to replace every time you upgrade is a great idea.

[@BloodyIron]

Didn't really "get" Power Factor (PF) until this video. Thanks for this!

[@Anatoli-y]

Hey! Nice content! If you testing and not sure about a device, just use a bulb lamp connected in series with it. It will prevent circuit from explosion.

[@conorstewart2214]

Not necessarily. It will limit the current to the current needed for the bulb, it is very similar to just putting a resistor in series.

[@Anatoli-y]

@@conorstewart2214 Not necessarily to put bulb?! It not necessarily till your circuit will explode one time. And resistor isn't similar, it got fixed resistance. Bulb have changeable non-linear resistance. Also resistor not will show you if your scheme is workable or not.

[@conorstewart2214]

@@Anatoli-y you misunderstood what I said. The bulb will not necessarily prevent the circuit from exploding. The bulbs resistance does change but it is still just a resistor and there are other ways of seeing if the circuit works other than just a bulb lighting up, all that means is there is power flowing, not that the circuit is working.

[@Anatoli-y]

@@conorstewart2214 It will prevent from a huge explosion and destruction on pcb from AC current. You also misunderstood what I said, it will show you that a pcb(device) is not short circuit. I use this method for a long time and its work perfectly. And what other ways?

[@cezarcatalin1406]

There are also PFCs that act more like filters. The input is AC mains voltage, the output is also AC mains voltage, but even if you hook up a dirty consumer with an abysmal power factor to its output, you still see a perfect power factor at the input.

[@caffeinatedinsanity2324]

Oh yeah, I remember when learning about the "power triangle" (apparent power is a vector made from real and reactive power) when working with 3 phase AC. When you want to compensate for inductive loads generating unwanted reactive power, we simply put a calculated capacitor in parallel to it. But I didn't know it was such a huge deal with DC appliances. I actually never thought chargers weren't SMPSs for the most part and were MUCH more rudimentary.

[@Pentium100MHz]

Switching power supplies are the ones with this current waveform. Older type power supplies with a 50Hz mains transformer have power factor of 0.9 or so, no problem there. In addition, they are simpler to repair and a capacitor failure is not so destructive. However, they are bigger.

[@Pentium100MHz]

@tripplefives I tried measuring the power factor of my vacuum tube receiver. The power factor initially was something like 0.95, then dropped to 0.87 or something like that once the tubes started conducting. The receiver does not have a filter choke, just two silicon diodes arranged as a voltage doubler. Another device I tried is a VTVM. It has a tube rectifier for B+, no choke and some of the tube filaments are DC (selenium rectifier). Instantly after turn on, it uses 52W, 0.97PF, then it drops to 30W 0.96 and once tubes warm up the power goes up to 54W and power factor to 0.92. Maybe the inductance or the resistance of the transformer helps smooth it out. I have seen DC chokes only on some tube radios (in some cases they use the output transformer as a choke), most devices do not have one and there was no problem with power factor until switching power supplies became prevalent.

[@bjn714]

PF of 0.58 (what that LED strip comes out to at 21W vs 36VA) is actually not _too_ bad compared to most small switch mode power supplies. I frequently see 0.4-0.5, which is more the norm for small power supplies. My secondary computer monitor as an example is 0.38 PF (my primary monitor has dual USB-C with PD on both, so its 340W power supply exceeds the required load rating to require PFC by law, so it comes in at 0.97 since it has aPFC).

[@neilw2O]

Many of these power packs will run on 385-400v DC if you know what you are doing and test carefully. Internally they already rectify to that voltage. Caveat: The rectifier in the power pack will only be using half of it's diodes and can possibly exceed it's rating specifications. Our farter, who art in evven.

[@martylawson1638]

I've seen a few manufacturers rate supplies for DC and 400Hz operation. It's rare but lets you run in spec with high voltage DC.

[@eDoc2020]

On the other hand in order to deal with the current peaks you get when running on normal AC the diodes need to be oversized.

[@samhorowitz7593]

Excellent video! We all need one, just like you said! Thanks!

[@redox3551]

Amazing content as always!! Can we have a tutorial vedio that shows the basics of using multimeters to reverse engineering circuits like you do? That would be great!!

[@greatscottlab]

Thanks. My first basics video was actually about Multimeters. Not sure if I will do another one.

[@aaron092000]

@@greatscottlab Do a poll on KZbin 😀

[@JxH]

Memory aid from the old days: "ELI the ICE man." (An 'ice man' is someone that delivers blocks of ice back in the pre-refrigeration days, not intended to be a prehistoric human.) ELI means Voltage (E) on an Inductor (L) comes before the Current (I) which builds up more slowly. ICE means Current (I) through a Capacitor (C) comes before the Voltage (E) which builds up more slowly. These are not really needed if you know how these components work, but it can help bridge the gap until trained-instinct takes over. It's a tiny bit interesting (very tiny) that only one symbol/letter out of four ('C') matches its word's first letter ('Capacitor').

[@ZipZash]

Love the videos! Wanted to ask if you were familiar on making PCB Antennas for custom Pcbs without needing to use external pre made modules like you have done before. I tried doing research on my own to help but nothing really helped me. A video from you would be very easy and informative to understand 👍

[@greatscottlab]

I can put it on my to do list

[@Aim54Delta]

Antenna design is kind of an art. There's some theories out there. They kind of work. There are two things about antennas. First is that all objects have an inductance and capacitance (which is what an antenna is). Length of an antenna corresponds to a value of inductance and capacitance. This also gets into wavelength. All of these factors become inter-related and everything becomes proportional to 1/4 of the wavelength (rise to peak, drop to zero, drop to trough, rise to zero in a sinusoid). It... is and isn't complicated. You're charging an extremely small capacitor that discharges across the inductance of itself, forming a tiny tank circuit. Because all of this corresponds to distance, you can get weird phenomena like reflections (you can "kink" high frequency electricity like you would a garden hose), standing waves (why putting metal in a microwave leads to arcing), etc. The second thing is that stripline works by preserving the symmetry of transverse modes... while microstrip makes a great antenna because it does away with said symmetry. To my knowledge, there is not, as of yet, a "theory of everything" for the electromagnetic spectrum. When does a tank circuit couple fields versus produce photons... and is it photons mediating between the coils of transformers?

[@ZipZash]

@GreatScott! I wonder how long that list is 🤔

[@ZipZash]

@@Aim54Delta ah, thank you for your information

[@Aim54Delta]

@@ZipZash en.m.wikipedia.org/wiki/Inverted-F_antenna#Planar_implementation Wikipedia has some information on them that could help. A lot of it is going to depend on the band you are using. We are ... going to be getting into some weird times with regards to governments and regulations. I have an SDR module on the way from an open source project that ... isn't too much different from the ELINT packages used by the military. I can arbitrarily pick a frequency and protocol, define a new protocol, etc. It's the "warning, you may violate laws by not knowing what you're doing" version. Granted, I know what I am doing and that is why I got the one that allows me to operate without constraints - but we are getting into a time when, even if the laws are being broken by the public, it's difficult to see how enforcement would be at all practical. I can troll an EA-18G with a $150 setup. Trampling the FCC with some pi picos and bent wire is almost an inevitable thing should something useful be found within a domain afoul the law.

[@paulmurphy3838]

No two ways about it my young buddy, you are super human, so good to see you analyse these components and shed light on all things electronic.

[@DLSDKING]

I love your analogy of foam/drink ratio in a cup to explain Apparent power/ real power. Im gonna call it gretscotts analogy when explaining it to my interns & students.

[@carlosteixeira589]

he didn't made that analogy, its an already old one

[@greatscottlab]

Haha yes. Pretty famous one. Usually beer is used for that.

[@DLSDKING]

@@greatscottlab Well, thats the first time i heard that,

[@glennlopez6772]

Thanks for the video! Your explanations are so thoroughly clear!

[@groo1887]

Good news is that most higher power AC/DC power supplies like those in your PC include PFC circuits.

[@greatscottlab]

True. Nowadays pretty much mandatory above 100 to 150W I think.

[@DSAK55]

it became a regulation in the 90s when businesses were running hundreds of 300w tower PC in one location

[@groo1887]

@@greatscottlab the addition of PFC circuits was especially important for large data centers. In the early days of Google our servers didn't have PFC circuits which was fine when you didn't have many. We quickly learned the importance of PFC when we started building clusters with 1000+ servers. Without PFC we would run out of power capacity. PF on average was close to 0.6. Later server designs required a minimum PF of 0.9. Now a days most servers have a PF of 0.96 to 1.0. PFC circuits have become extremely important and have come a long way.

[@groo1887]

Another thing to mention is that bad PF leads to heating and premature wear of upstream transformers. Power companies benefit from good consumers of power.

[@zwidewe2764]

This totally depends on the standard requirements. E.g. IEC61000-3-2 for single phase devices or -12 for three phase devices. Only the cheapest solution to keep it will be implemented. In the lower power range mainly passive PFCs are used. Just shaping the current as little as necessary. Money rules, not the technical best solution.

[@heatherryan9820]

I always learn so much from your videos, I usually have to watch them a couple times just so I can get a good grasp on what you’re teaching, lol.

[@tscc]

Guess I'm glad that when building my 3D printer back then, I sprang some extra money for an active PFC power supply. I'm sure the various PWM driven loads create some kind of havoc power factor wise.

[@analoghardwaretops3976]

Un Compensated Reactive loads cause the havoc...pwm has no direct impact on pfc.

[@laurianlamba]

Excellent, great job with the video! Perfect explanations !❤

[@averymahan3795]

What I'm currently learning in class is that power factor correction occurs near powerlines. That is, the sum of the loads in a particular building are balanced adding shunt capacitors on power lines. Could anyone comment on this in relation to the video topic?

[@greatscottlab]

Yep. That is a kind of passive PFC. Measuring the phase shift and then adding caps accordingly.

[@Nelo390]

And the reason this isn't done at the powerstation itself is because that would still require thicker wires to carry higher current?

[@averymahan3795]

@@greatscottlab Sweet, and the question I was getting at was if they accomplished the same thing? Specifically in regard to the precision, I guess devices with built in PFC act as scalpels on larger systems.

[@analoghardwaretops3976]

3 phase capacitor banks with current limiting inductors switched in & out of circuit as required... Early days it was with relay logic.. Later on through Z.C.D. THYRISTORS. Then phase control Thyristors replaced them ..( precise control of current is difficult in above cases) Nowadays same is done with SERIES BACK TO BACK I.G.B.T.'s with full pwm & current control... Each capacitor bankwas built up of 3 or more sub banks where each sub bank have different bulk capacitance....so different values can be selected as per demand.

[@analoghardwaretops3976]

Another reason is attempting to achieve equal load distribution of all 3 phases...active P.F.compensation does this..but other issues are to be considered...line harmonics..so harmonic filters are used..(active/ passive) also if such need them across lines or in series or both.. Neutral current monitoring / reduction & weather system requires floating or neutral point clamping..all involve deep practice & understanding of power distribution systems.

[@joerod7526]

I can listen this guy for years....his so funny.....and EXPERT

[@greatscottlab]

Oh stop it ;-)

[@smichels5117]

Very helpful and clear explanation of PFC. Thank you!

[@YSPACElabs]

I've always known PFC as "that thing that makes your devices work at both 120 and 240v without them blowing up". Very good video. Definitely learned something.

[@MCsCreations]

Fascinating stuff indeed! Thanks, dude! 😃 And yeah, I'm going to need a power supply pretty soon! Stay safe there with your family! 🖖😊

[@sanjikaneki6226]

In the EU it is already mandatory for commercial devices that use more then X W But if it is a china import it may be avoided for better or worse. Well for super small loads like that LED lamp adding PFC would cost a ton and to make it worth it you need to increase to lot the life time of that LED so costs simply balloon.

[@greatscottlab]

True

[@hoverbovver]

We have a building with 30 LED lights and I can't get a UPS to act as a mains fail backup on it. Did when the LEDs and UPS were new but I think the LED's power factor has deteriorated with age so the UPS can't cope with them now.

[@sanjikaneki6226]

@@hoverbovver interesting also since it is LEDS maybe a more DC solution is better?

[@tomasbengtsson5157]

75W and above requires PF 0.9 or better. Under 75W 0.5 or better. What we learn from this - don't buy crap 😂

[@markflint9089]

Yes, the PFC circuit does reduce those harmonics for the device it is correcting, BUT due to all that PWM activity of the mosfet in the boost converter it could well be adding tons of harmonics back onto the AC mains. (Do a 'before and during' test with a spectrum analyser.) While this is not a reactive power issue this 'dirty' electricity has been shown to add to the EMF smog in the house and beyond.

[@issaccartwright736]

At first I thought it was weird that music and electronics have so much in common with graphs and hz and harmonics and stuff. But it’s not really that weird when you actually think about it. Also. Music will only get recorded thanks to electronics these days so oscilloscope graphs looking like audio waveforms makes quite a lot of sense. What is weird is that I am not the only audio engineer I know that has a moderate understanding of electronics. Maybe there’s a whole bunch of us that just know how to translate different graphs to different things.

[@hugegamer5988]

Much of the math is literally identical across many fields because of physics fundamentals. For example the 2nd order differential equation to model a flywheel and a spring is the same as an inductor and capacitor. If you know how a hammer works you can intuitively understand what happens when you suddenly stop current in an inductor.

[@modernbassheads5051]

Yeah I know a dude who designs subwoofer enclosures based off math from circuit design , uses capacitive reactance, etc.. idk too much for my brain to understand

[@modernviewscience6745]

Great! And my own handwriting looks like old Egyptian, while yours is very neat and clear. I am jealous! Thanks for the explanation in apparent and real power. Splendid!

[@yourdiytechlife]

Great video! PF is something I rarely think of but it definitely can impact our modern systems in a big way.

[@goodfriend6428]

Excellent1 Thank you!

[@martingerken7094]

And how many watts does the PFC consume? I see a large heatsink...

[@greatscottlab]

Depends on the load of course. But yes. I does decrease the efficiency of the power supply by a couple of %.

[@johnwalton5576]

Very interesting! I learned a great deal. Thanks for sharing your knowledge with us!

[@Gamezone-sd3er]

Now I understand why Nikola Tesla won the fight against Edison 😀 thanks for this information 🤓. From now I won't plug my power supply for 24/7

[@carultch]

Tesla won the current wars because of transformers. In the time of Tesla and Edison, the only way to convert between voltages, was to use transformers and AC power. Edison's DC system wouldn't efficiently transmit power over long distances, since it was limited to the voltage at generation, and the voltage people would use in their homes. The DC:DC converter wouldn't be invented until the 1950's. Had it existed in Tesla and Edison's time, we could've had DC distribution.

[@Gamezone-sd3er]

@@carultch yupp but both ac and dc have their pros and cons so both are useful in certain places. @Electroboom even maided a detailed video on this topic.

[@WaylanEE]

I see more future for my business thanks to you.

[@DrHarryT]

Couldn't you just feed the HVDC directly into the device and just let the internal rectifier flow through? Sure only half of the rectifier would be in use, which half would be dependent upon polarity, meaning polarity would not matter.

[@GregorWSky]

Nice. Active PFC has been on the market for good PC power supplies since quite some years, but I guess it has to be everywhere. Chargers, LED light, everything that does not is an ohm resistive load.

[@CarbonPanther]

How do i determine whether or not a PSU has a PFC when i can only look at it from the outside of the enclosure it's in?

[@Gengh13]

It should be specified in the manufacturer specifications(they usually tell you the min power factor) or you can test it, or you can see the components inside.

[@eDoc2020]

Oftentimes you can't without testing. An exception is that if a power supply has an input voltage selection switch it is nearly guaranteed to lack active PFC.

[@SauvikRoy]

Wonderful explanation! Another great video!

[@Iron_Condorr]

0:44 fart 💩

[@greatscottlab]

Ups

[@sethunthunder]

nah u cant unhear it 😂

[@shivavarunadicherla]

This is just on time. I was learning about computer PSUs and you just showed up with the perfect video. Thanks

[@cabeloDoPardal2]

0:43 who farted?

[@greatscottlab]

Not me

[@sandordugalin8951]

I learn the most important stuff from this channel. Real practical electrical knowledge, explained in a way I can understand.

[@ppirky]

Welcome to the farting teacher's channel!

[@greatscottlab]

Haha. It happens ;-)

[@mevk1]

@@greatscottlab A Real Ripper kzbin.info/www/bejne/i2bGoqWondZsiqM

[@duality4y]

Applied Science has a real nice video on this topic.

[@matjazwalland903]

A very good explanation of the efficiency of the used electrical energy. The problem that arises is with dirty input energy. Where various devices connected to the network leave traces in the form of high-frequency harmonic oscillation. These phenomena are best observed in high-rise buildings with several apartments, which are connected to a single transformer station! Another point that you can show is at what DC input voltage the device starts working normally and if the components can withstand the DC stress. Capacitors are not the best friends with direct current because it fills them up and doesn't let them breathe, causing them to burn out. And manufacturers use these stress statistics to make products with an approximate lifespan of around 5 years of constant use. However, coils have an enemy in high-frequency pulses, because their property is inductive in nature, they create counter currents and amplification of the electromagnetic field from the surroundings into the very circuit that we use. So that in a society with more and more devices that use wireless technology, it is necessary to protect the coils from the signal-filled environment. It would be nice to have an efficiency coefficient close to 1, but until this is put into law and forces manufacturers to comply, I don't see why they would do it by themselves and guarantee a long working life of the devices. Just looking at smartphones and computers, even if the device itself is still working after 5 years, we now have to throw it in the trash because there is no software support, and spare parts stop being produced after 3 years of the product release! And let's not forget that just one such device usually costs at least two salaries of an average working person. And everything that is cheaper no longer has service or software support!

[@andrewkay9226]

Thank you once again for your clear, easy -to-understand explanation. Love your videos

[@stevecann3394]

...and now I know what power factor means....thank you!!😀

[@vaibhavbalyan4804]

Love your videos Brother. I am an Electrical and Electronics Engineerand each of your video makes me correlate to the theory that I encountered during my graduation. I always liked to experiment around with all these stuff but to set up a testing and experimentation station is costly. And, the university didn't use to provide time and resources for undergoing such experiments to graduates. However, seeing your videos make my dream of testing and analysing electronic projects come true. Thanks again man. I Love your content. Love from India. Keep on blessing us with knowledge. 😊

[@Comrade_YG]

He farted at the 0:44

[@simonlinser8286]

I need to learn more about this, thanks for the video.

[@anilkinikar]

Awesome! You explained so nicely. That's why I love your channel. Keep it up. 👌

[@BrotherLuke2008]

I like this type of video far more, Scott!

[@BADALICE]

Mindblowing. So cool.

[@johansvideor]

Grid operators have big synchronous compensators (also called synchronous condensers), that are basically free spinning synchronous motors, to actively adjust conditions in the transmission grid. They are a more flexible alternative to capacitor banks. They were introduced in the 1930's and have been in widespread use since 1950's. They are still needed, especially due to wind and solar farms. In my opinion there should be requirements for PFC also in consumer equipment. There is so much crap out there.

[@insightfool]

Thanks for the clear explanation.

[@awesomedee5421]

You showed us a board and a IC, but didn't talk more of the details. I don't know what makes a good active PFC board or nothing really to identify what might be a bad PFC board design to avoid. This is an interesting topic that I'd like to hear more info on.

[@1NeoGio]

A very interesting video thank you! Something that most people will never consider due to displayed wattages on products and the accompanying assumptions that this is the only figure of concern. Well done GreatScott! :)

[@keltonfoster]

It's always nice when components work and don't blow up😁. Listening to you talk about these electrical circuits and how they function is like trying to understand someone that speaks another language. I get some if it but you have such a good understanding of it it's just second nature to you. It's the same way when I try and listen to a MD talk about medicine and the more advanced science involved with treating patients when they talk to another doctor.

[@jerryz716]

PFC were mandated in the EU for all PC power supplies in the late 1990s. Worked at a large electronics OEM manufacturing company and was directly involved in implementation of these changes, we produced power supply's for customers like IBM, Compaq, Apple, Olivetti and others. It amazes me that they have not been more widely adopted in other countries.

[@AlanSanderson-u4t]

I worked at HP and we had to comply with IEC 555-2 which came about because switching power supplies were creating excess current in the neutral wire which was typically undersized compared with the phases. That resulted in house fires in Germany when the neutral overheated. We designed PFC into power supplies that we deployed worldwide. It would be difficult to find a switching supply that meets regulatory requirements (FCC, CE, TUV, etc.) without PFC.

[@gregorymccoy6797]

Very good presentation. This is something I was only dimly aware of and really benefitted from this.

[@paulmeynell8866]

Cool , I still learn something new every day 😎

[@RomanoPRODUCTION]

Cool, please make a Part 2 of PFC. Thanks!

[@dgb5820]

Great video Scott

[@CandleMan5]

That cola glass example was genius!

[@Ralphs-House]

I always felt that resistors contribute to wasted power. You're effectively burning off energy in the form of heat, just to reduce the voltage.

[@christianlingurar7085]

oh, whow, big thanks! I'm a small-tier electronics and mc hobbyist, but I was totally unaware of it, I only knew it from small power supplies, but never researched what that exactly means

[@RomanoPRODUCTION]

01:45 The SMILE is here. AWESOME. ;)

[@electronic7979]

Nice video 👍 I liked it

[@EasyOne]

Very well explained

[@greatscottlab]

Thank you :-)

[@carloshorva4577]

thank you scott. i have a project and went straight to mouser.

[@greatscottlab]

Awesome. Glad you like their stuff as well.

[@iamdarkyoshi]

Excellent video! One of the most apparent circumstances where a poor power factor can be an issue is when using backup inverters. Your 1500VA backup inverter is only going to reach 1500W if you've got a perfect load on it. If you've got a poor power factor, you'll have to derate the power rating!

[@davidyeager8869]

Great point! I blew up a couple of cheap inverters trying to charge e-bikes with a cheap chopper charger. I assumed a 500w inverter would run a charger with an output of 100w easily, WRONG!!

[@yxcvmk]

Just experiencing PFC in practice with a portable PowerStation and a compressor ice maker. Plugin power meter shows ~80W, with a PF of 0.5. The power station seems to draw 150-170W from the Battery as far as I can tell, and with that the *battery drains much faster than expected.* Now I will watch the Video and see if there is a "plugin-between" solution between ice maker and inverter.

[@m.d.hofman4236]

Loved this explanation. Keep up the good work 👍

[@allezvenga7617]

Thanks for your sharing

[@n8p275]

Don't know how you did it, but the audio on this video is amazing