I think the capacitor was harvested from a 'power saver plug' and it's delivering it's free power.

@--_DJ_--

Жыл бұрын

Could there be a better answer?

@the_expidition427

Жыл бұрын

@@--_DJ_-- I think there couldn't be a better one

@kilasracingfactory

Жыл бұрын

made my day mate

@SteelHorseRider74

Жыл бұрын

😂

@jamesslick4790

Жыл бұрын

🤣

Note that the Power Factor has improved from 0.668 to 0.829. The capacitance is effectively correcting for some of the inductance which is opposing the current flow. If you increased the capacitance further, the capacitive impedance would be equal (and opposite) to the inductive impedance, cancelling it out. This would be at the resonant point, and the circuit would be purely resistive. It would also be going like the clappers.

@rich1051414

Жыл бұрын

That does give me ideas on an alternate way to add 110v compatibility to a 220v fan... by INCREASING the efficiency.

@chitlitlah

Жыл бұрын

Yeah, the power factor is a giveaway that the reactance has gone down. It could either be a larger or a smaller capacitor that moves the reactance to zero, ie the one in it might be too large and is causing capacitive reactance.

@MikeRatcliffe24

Жыл бұрын

It would be going the same speed tho? as its a synchronous motor and its speed is only a multiplication of the AC frequency, im not aware of power factor correction changing mains frequency hz [only phase shifting it in time].

@IceBergGeo

Жыл бұрын

​@@MikeRatcliffe24not likely a synchronous motor. Small fans like that have a different style of motor. Shaded pole is likely what it is. Either way, it's not a frequency dependent motor, like sync, or scim.

@IceBergGeo

Жыл бұрын

I came here to say basically the same thing. Power factor correction, but inline. Causes the voltage to increase in the middle... It would be interesting to see if a lower OR higher value of capacitor would make the voltage across the motor (and capacitor) increase, as the power factor didn't specify whether it was leading or lagging after the capacitor was installed.

Resonance. The capacitor and the inductance of the fan are resonating, causing, as you say, a phase-shift. Without the capacitor, much of the current is reactive, not contributing to the output power. With the right capacitance some of the inductance is compensated for, lowering the impedance of the total circuit and allowing more current to flow. As the impedance of the fan itself will stay constant, and the current has gone up, the voltage across the fan also increases.

@strenter

Жыл бұрын

Sounds reasonable. I would have tried to explain it similarly, but in a worse way because I don't speak English natively. 😅

@idjtoal

Жыл бұрын

So the next thing to do is test with a range of capacitances, see where the effect happens, ?

@TDGalea

Жыл бұрын

Meanwhile I would've just thought it was bridging the gap where the AC dropped to 0v as it swapped direction. Very good explanation.

@mattmoreira210

Жыл бұрын

​@@idjtoalsounds like a valid experiment to me!

@henryokeeffe5835

Жыл бұрын

@@idjtoal yep! Although the optimum value that produces the highest power will probably cause the fan to burn out. It's not like the manufacturer tested it like that.

_"The voltage drop across the inductor is larger than the voltage applied to the circuit. This might seem to be an impossible condition, but it is not; the explanation is that while the energy is being stored in the inductor's magnetic field, energy is being returned to the circuit from the capacitor's electric field, and vice versa. This stored energy is responsible for the fact that voltages across reactances in series can be larger than the voltage applied to them."_ - *1968 ARRL Handbook, page 36*

@seedtheskies

Жыл бұрын

This is the reason for most of the common TV failures. Manufacturers save 3 cent per capacitor by not using higher voltage ratings. Effectively saving hundreds of thousands. Capacitors rated for just at the very "higher voltage" that you speak of. HVAC/R caps are the same deal, everyone uses 440 v rated caps while the 370v were failing too soon. Many environments were seeing 382 volt as an average(I'm ballparking) across every system. These are designed for a specific lifespan, similar to led lights. The target is like 50k hours. These things are calculated to a science...an economic science. What's worse is that getting rid of PCB oils(forever chemicals) has cost the consumer astronomically die to the quicker degradation of the caps newer dielectric oils.

@_general_error

Жыл бұрын

@@seedtheskies Are you claiming that environmentaly friendly "capacitor oils" result in shorter capacitor live span? Wait, isn;t there supposed to be an electrolyte in an dielectric capacitor? What kind of oils are you talking about?

@gyrgrls

Жыл бұрын

@@seedtheskies Most consumer device failures are caused, actually, by the temp rating of Mylars or Electrolytics, especially in applications such as older CFL lamps. Using 85 or 105 deg C rated devices is asking for early failure, because temperature rating is time dependent. Why make them to last twice as long if you can save a nickel?

@spvillano

Жыл бұрын

@@seedtheskies caps use a dielectric, but they've not used PCB oils in decades. Most have long, long, long used manganese dioxide as the electrolyte. What fails is the seal in electrolytic capacitors, allowing the lead to foil bond to oxidize, increasing the ESR of the capacitor, plus electrolyte drying allowing the oxide film to break down between plates and overpressurizing the capacitor. The voltage rating being a bit low is a part, but a larger part is the infernal habit of placing electrolytic caps right up on heat sinks, allowing the rubber to degrade due to the increased heat and oxidative damage from the air. The last oil filled caps I ever saw or heard of were motor start and run caps for industrial equipment, although some were used in consumer goods like refrigerators and air conditioners. No need for that, as mineral oil does quite fine as long as it's kept clean and not exposed to air.

@donovanhill7367

Жыл бұрын

@@gyrgrls If you can save a nickel AND sell them a new unit!

Looks normal. In a series LC circuit, the sum of the voltages across the capacitor and inductor will always be greater than the supply voltage. However, if you connect a two channel oscilloscope, one channel across the inductor and one across the capacitor, you'll see that the two voltages are not in phase.

@thandle61

Жыл бұрын

ELI the ICE man anyone? :P

@pengiswe

Жыл бұрын

Nice explanation. Just a bit of caution though. If you connect an oscilloscope like that, use differential probes, not the normal ones. They do not have a floating ground

@andymouse

Жыл бұрын

@@thandle61 Leading voltage or current in Inductive and capacitive circuits ?

@fromaflafl2198

Жыл бұрын

the speed of the fan is controlled "only" buy the frequency and the number of poles in the motor. RPM =( frequency /(poles /2))*60 . so what is happening is he makes a RCL oscillator. and increasing the frequency to properly 80 - 100Hz.

@lasagnahog7695

Жыл бұрын

I genuinely love reading jargon like this that I don't understand.

I think this test deserves a counterpart. What about putting an inductor in series with a capacitive-dropper powered LED bulb. 😁

Isn't the capacitor resonating with fan inductance drawing more current and amplifying the voltage across it?

@glintytear

Жыл бұрын

I thought the capacitance would instead reduce the overall resonance since it'd be effectively cancelling out a part of the fan's inductive reactance...

@bogganalseryd2324

Жыл бұрын

So, when will you make it go BOOM 😬 I resonate when you make things go boom 😂

@sirnikkel6746

11 ай бұрын

I *resonate* with this thought

@kreynolds1123

6 ай бұрын

​@@glintytear in a serries circuit, Impedence Z=sqrt(R²+(Xl-Xc)²) where Xl=inductive reactance and Xc=capacitive reactance Where Xl=Xc, then the circuit reactance = 0 and Impedence = Resistance.

Oscilloscope time!

You knew something. I don't just go around randomly adding capacitors to fans. It is considered inpolite where I come from. Love your channel.

As other commenters have said, it's getting close to resonance. Another way to look at it is to think of impedance as a complex number, where a capacitor has negative imaginary impedance, and an inductor has a positive imaginary impedance. When you add the positive and negative impedances in your series circuit together they partially cancel, and the total impedance goes down. In theory you should be able to find some capacitor that perfectly cancels the inductance of the motor windings; this is at resonance. At that point the circuit will behave like a pure resistor and the power factor will be 1. This is all in theory of course... you should experiment more!

@acmefixer1

Жыл бұрын

Positive and negative *reactance*, not resistance, not impedance. The two combined, along with the vector sum of the resistance equal the impedance.

@seedtheskies

Жыл бұрын

At near a perfect power factor, the fan may not spin in the direction you want.

@seedtheskies

Жыл бұрын

​@@acmefixer1ah, the Ole r1 and r2

@Gary-sv1ck

Жыл бұрын

magic sounds better

@threeMetreJim

Жыл бұрын

At resonance, the only resistance will be equal to the dc winding resistance of the motor and the current at a maximum. Whether the motor can survive this or not, you'd have to guess from the thickness of the windings (or just watch the smoke come out).

In terms from many Basic Electronics textbooks, this is a classic example of ELI the ICE man. A mnemonic to help us remember "Voltage (E) leads current (I) in an inductive (L) circuit, whereas current (I) leads voltage (E) in a capacitive circuit."

How ironic would it be if Clive is the one to really discover the first "free energy" device 😅

It would be interesting to see how it performs with different capacitors. Could do it so you get minimum impedance like you're taught in electronics classes when getting it in resonance. Honestly, it would make for a pretty cool example in a classroom of how it works, rather than having six boards, and fifty minutes of equations, followed by a "Any questions?"

Pay attention to the power factor in both of these cases. The capacitor is correcting for the inductive reactive power and you are getting more real power supplied to the load. If you break up the true/reactive/apparent power in both of these cases, you will see why this is happening

A classic problem we sometimes present to EE Uni students for explanation!

This does work, tried it. Just make sure to put a bleeder resistor parallel to the capacitor if you use this regularly.

The power factor increased as well. Intriguing, hope to see a follow up

We did something like this when I was in college except it was with a frequency generator, a capacitor and an inductor. As you get closer to the resonant frequency there is an amplifying effect based on the Q factor of the components. We were putting in 1 volt and, with fine tuning of the frequency, some of us got over 80 volts across the capacitor.

@khashayarmodaberi4958

Жыл бұрын

WOW!! It's So Huge!!

@robertoricardoruben

Жыл бұрын

it's the voltage across the resonant circuit times de Q of the LC circuit. That's why RF circuitry which is rated for low voltage needs high dielectric strenght insulators.

The exact same thing happened to me when I tried to reduce the speed of noisy a fan, with a capacitive dropper😂😂. Some values of capacitors would slow the fan down, BUT if you hit a sweet spot valve of capacitance , then the fan went mental speed!!! I think the inductance of the motor and the capacitor are forming a tuned resonance circuit. It was quite cool to observe at the time. Thanks for reminding me of this. I would love to see an oscilloscope trace of the wave form.

Your videos always resonate with me Clive 😉

I think it's a resonance/decreasing impedance thing. The reactance of the load decreases because the series capacitor's capacitive reactance cancels some of the inductive reactance from the fan. The power factor also goes up, which means that this is probably what's happening. Now you just need to try a capacitor that's a little bigger to get less impedance and MORE POWER.

Increase the capacitance to make the power factor 1.0 then use a variac to reduce the supply voltage until the wattage is back down to the fan's normal value. Now you have an efficient fan.

Together with the coil in the motor that capacitor forms a tank circuit. The capacitive and inductive reactance basically cancel each other and the voltage on the inductor can rise above the supply voltage. At resonance in a series tank circuit the current is only limited by the resistance of the wiring and the coil. So if you use that fan in long-term operation with the series capacitor, it may reduce it's lifetime. Btw I'm using a series LC circuit with a halfbridge driver in the transmitter of my diy wireless power transmission system. I've already measured up to 800Vpp on the coil in the tank circuit, even though the supply voltage of the halfbridge was only 30VDC from my bench power supply. You don't wanna touch that.

Yeah i figured the capacitor trick out a while ago on a whim, saved heaps of headaches. Clients complain the fan is running slow but instead of replacing the unit i tried the capacitor and it worked, saves trying to find replacments for fans that go in and out of style every couple of years

Aliens, its always Aliens 😂😂😂😂

@TopEndSpoonie

Жыл бұрын

It is COVID.

Clive, your capacitor in series with an inductor has introduced a resonant rise in voltage, current, and overall power. I've done similar tricks with a transformer in series to get the voltage rise 😊

I'm glad I"m not the only one who experienced something like this. My desk fan, rated 120v .33 amps @ 60Hz in series with a 10uF capacitor was getting just about 240v due to the boost. One difference is I thought mine went immediately to double voltage and yours is taking some time to reach only 33% more voltage.

This is exactly how capacitive start motors work, albeit once up to speed, the capacitor is cut out of the circuit. The simple connection you made is how we power 240v fans in North America from 120v lines.

Adding a capacitor created a resonnant circuit, maybe not perfectly tuned, but still a resonant circuit. They tend to create higher voltages or currents that what comes from the power source. Thus your power and voltage readings where higher than expected.

Positive reactance is cancelling negative reactance, resulting in higher current. This is somewhat limited by the back voltage from the motor. You'll also note that the power factor went from 0.6 to 0.8.

@KNfLrPn

Жыл бұрын

The power factor is the biggest giveaway.

@seedtheskies

Жыл бұрын

This is why capacitors are used in industrial settings where they can save you on the power bill. In the US, our residential is only billed for used power. Capacitive and inductive reactance only really apply to your bill with 3 phase meters.

@Gunbudder

Жыл бұрын

presumably you could tweak the series capacitance to tune the circuit to get the PF to .95 ish? its interesting to see power factor play out like this

@whitslack

Жыл бұрын

With a PF tuned as close to 1 as possible, would the fan spin as fast as possible for the given supply voltage? Would the motor windings get hotter, or would they in fact still be carrying the same total current, just more of it being "real" (i.e., in-phase)? The reason electric companies hate poor power factors is that the unused current still has to traverse the transmission lines, so I'd guess the fan motor windings could be carrying the same current even with a well tuned PF.

@seedtheskies

Жыл бұрын

@whitslack the drawn current should be nearly the same, regardless of PF. The fan would spin faster in theory, but remember that it will have more load from air. If it moves faster than the available load from air, it will be in a stall state amd reduce current for the relative rpm. The fan will run cooler temp on the windings as a result of correct phase alignment. Startup with a near perfect PF will result in longer inrush current period. Capacitance or voltage needs to be lagged for directionally and overcoming inertia. Most manufactures want 90 degrees out of phase. Newer ecm motors and single phase motors driven by vfd will approach the sweet spots for as good as they can get on PF after either rpm speed is achieved or near stall state. Sometimes this is read by polling voltage, current, PF, or emf....depends on manufacture.

Howdy. I think Yiu are on the right track. A series resonat circuit will show low resistance at the ends and high voltage between the inductor and the capacitor. So yes. A series capacitor will boost the voltage over the fan. Regards.

Some of the cheap fan speed controls use capacitors for reducing fan speed, but who would have thought to apply series resonance for the opposite effect. Great video! Should work with some super-cheap fluorescent light ballasts too!

As others have mentioned, it has something to do with LC resonance but I just wanted to add, I have used smaller value capacitors to drop the voltage and run small 110V induction motors on 220V without the losses of using a resistor. This video shows what would happen if you want to drop the voltage but get the wrong (right?) value capacitor.

I have been doing that for years. Had some nice 240V PABST fans that I wanted to use on 120V equipment. Just put a capacitor in series and that boosted the voltage up to 190V. I don't like noisy fans so I run them at lower voltage for more slip. Resonance. Surprised you didn't put the voltmeter across the capacitor too. That would have higher voltage too. Sometimes I've guessed at the wrong cap value with a transformer and had it instantly burn up.

It isn't always obvious to folks who don't work with RF (Radio Frequency) electronics, but you achieve maximum power transfer between circuits when the output of one circuit (the mains) and input of the other (the fan) impedances match. As several folks have already commented, the fan represents an inductive load and by adding the capacitor in series you are better matching the load (fan) to the mains. Bear in mind, that match is also frequency dependant so depending on if you have 50Hz VS 60Hz, will also make a difference. Good motor designers try to make sure the inductance of the motor is resonant at the AC frequency in which it is designed to work so my guess is the fan motor you have is not resonant at the AC frequency where you are, and you helped correct that deficiency by adding the capacitor.

@jimturpin

Жыл бұрын

Just to throw in an additional comment, if you wonder how they make those cheap ceiling fans have a low, medium and high speeds, they switch in capacitors of different values to change the impedance which impacts the circuit matching to give different speeds. Its not pretty, but it works fairly well.

You just discovered how 3 phase AC motors are connected to single phase with start kick capacitor. Congrats man.

As others have said, this is a sort of power factor correction (though often power factor correction uses parallel capacitors, not series capacitors). I ran through the numbers for this. It's nice to see that theory works. For the circuit without the capacitor, the complex power can be calculated using the real power and power factor provided by the HOPI, and then in turn the equivalent impedance of the motor can be calculated to be Z_m = 1769+j1987 Ohms. The 1uF capacitor has impedance Z_c = -j3183 Ohms. The series combination of the motor and capacitor has impedance Z_eq = 1769 - j1196 Ohms, which is smaller in magnitude, and thus will draw more current from the line (which is at 240V). Specifically, the expected current will be 240/Z_eq = 0.112 A with phase 34.1 deg, which matches pretty well with the measurement of the motor with capacitor (within tolerances). If the capacitance were about 1.6uF, it would make the series load look almost entirely resistive (and make the motor spin fastest).

@spvillano

Жыл бұрын

I remember back in electronics school, I was bored, so I put in a modest resistor to monitor current, then slapped the oscilloscope on in vectorscope mode to see the phase angles on the inductive motor, the capacitor and the current angles. The instructor loved it and apparently, added it to the power factor correction class later on.

@TheBalconyWorkspace

Жыл бұрын

This is the most clear and precise answer. Good for you dude.

@Dazza_Doo

Жыл бұрын

Wait, are you saying there is Build up of Electrical Energy that can't pass though the capacitor and therefore is dispersed though the Motor instead? If that was true then only 1/2 the wave form could pass through the motor, which would make it pulse. Electricity doesn't flow in wires. Maybe I miss understood you

@spvillano

Жыл бұрын

@@Dazza_Doo yeah and resisters are also diodes. Seriously, the subject is over a century old!

@Dazza_Doo

Жыл бұрын

@@spvillano you know what is over a century old, Why is the Sky Blue The Sky is blue because... the Electromagnetic wave length is filtered at the wavelength Air likes to absorb, it is then Scattered and perceived as Blue light and the Sun is perceived as Yellow, even though the Sun puts out Pure White Light. My Story is this: "Resisters are also diodes", doesn't tell me anything of value in regard to this video. I'm really not sure of your meaning I'm trying to learn, for me there is nothing to debate. I'm I going to play "So you are saying" game? OK So you are saying that the capacitor is NOT in resonance and has become a perfect Resistor and Since as you said "Resisters are diodes" does that mean you think the Capacitor is now a Diode. I know that Diodes with a AC energy, only gives 1/2 of the energy in 1 direction, there by reducing the fan speeds, since it has 1/2 the wave form of energy? End Of Line

Hook it up to a signal generator and measure the voltage/current waveforms with various capacitors and input frequencies. It doesn't need to be tested at 240v.

@Rubensgardens.Skogsmuseum

Жыл бұрын

Think you ment oscilloscope. Don’t mean to be picky but a lot of pwople come to the comments to learn. I come here to realize I need reading glasses. So sorry for the spwlling.

@TheTemporalAnomaly

Жыл бұрын

@@Rubensgardens.Skogsmuseum What he means to say is look at how the circuits inductance and capacitance interact at various frequencies. You would do this using a frequency or signal generator and you would observe the wave forms and voltages on an oscilloscope. That way you could see how close to resonance you are getting with different capacitors. Like the OP says, this can be done at any convenient voltage level. He has not made a mistake by saying `signal generator`

This is a classic case of a tuning circuit - you can clearly see the power factor increase once the capacitor was placed into the circuit. Interesting observation. Could probably keep tinkering with differing values of capacitor (assuming the fan doesn't die first). Nice to see something I was taught in electrical theory actually have an easily seen effect

Inductor + Capacitor = Resonance

You also corrected the power factor, I think it's the same as passive power factor correction in switch mode power supplies. It takes current during the crossing point (which would otherwise be fed back to the mains) and passes it to the load. Obviously the load is the same so the only thing that can change is the voltage.

@benbaselet2026

Жыл бұрын

Except usually PFC caps are supposed to be parallel to the load, not in series which makes it pretty interesting.

@wafikiri_

Жыл бұрын

​@@benbaselet2026It works equally well. When in parallel, voltage is shared, current acquires a cyclic component that enters the capacitor from the fan's coils, to be reversed half a cycle later. When in series, current is shared, and voltage at the node between capacitor and fan's coils is what acquires an extra cyclic component.

@dl5244

Жыл бұрын

@@benbaselet2026 and usually PFC doesn't result in 70% more active power consumption (unless your caps have failed short)

Crosscheck it with a lightbulb or similar of the same wattage, you won't get any resonance because of the lack of inductance.

haha, i actually was experimenting with caps a while ago when i had barely any knowledge about electronics, and i dont know how i got the idea to plug one of those fan caps in series, just like you and i was damn impressed on how much more air it moved lol, and that being almost 5 years ago and the little fan is still moving air to this day

I love it when you find random oddities like this. Reminds me of when I discovered by body was capacitively coupled to my mattress springwork which in turn was capacitively coupled to a USB cable shielding laying across the mattress which went to a audio DAC and homemade amplifier. While touching my laptops ground and laying on the mattress, I would get a 50Hz hum on the audio, the amplitude proportional to how much surface area my body had with the mattress. If I stood on the floor while touching there was no hum, as soon as I placed my other hand on the mattress it was humming. It was the result of improper grounding with my laptop PSU, TV and amplifier PSU. Possibly the cheapo USB DAC and maybe old house wiring. I fixed it by attaching earth grounding lead to the TV chassis, the plug didn't have one.

Hah! I'm lucky enough to have had this taught to me in high school! And unfortunate enough to have forgotten most of it in the 30 years since! 🤣 Didn't know (or forgot) that this could impact things like fan speed though. I think we mainly discussed it in terms of the power factor, and correcting for it in say a factory, because the grid don't like big inductive or capacitive loads. Can't remember why though. Anyway, now I think I understand how variable speed fans work. You know, the ones you use in summer to stay cool, and that have like 3 speeds or something. Got one that's falling apart mechanically, might open it up to verify my theory. Cheers mate, and thanks! Also big big thanks for not making this one of those "shorts" abominations.

If you have an oscilloscope, checking out the waveform could be interesting. I'm wondering if it has something to do with the fan being an inductor.

@st_us

Жыл бұрын

Do another Video Showing this please

@mattmoreira210

Жыл бұрын

It has, in fact, _everything_ to do with it being an inductor 😉

@SlyerFox666

Жыл бұрын

everything to do with the inductor being an Integrator and the cap also storing energy resonating together.

@markevans2294

Жыл бұрын

There's also the complication that the fan generates back EMF when running. The frequency of which is going to depend on the rotation speed of the fan. At certain speeds this will be a simple ratio of the 50Hz supply.

@XXXXIndices

Жыл бұрын

Even better show the voltage and current on the oscilloscope, I think you will see that the current peak will be closer to the voltage peak when the cap is in series.

Yeah, the explanation was great, thanks!

Fascinating! 🖖

It would be interesting to put an oscilloscope on it and see what the voltmeter is actually measuring.

Are we sure it's not April the 1st and Clive is having us over? But seriously, I think it's time you break out the oscilloscope and track the voltage and current phase relationship with and without the capacitor; I think you may find it's bringing the voltage and current into phase alignment.

@bigclivedotcom

Жыл бұрын

It's real. But there must be some interaction to increase the voltage. The power factor does improve.

@petersage5157

Жыл бұрын

@@bigclivedotcom Yeah, there are a lot of pages about LC resonance. Both the voltage across the inductor and capacitor are higher than the supply voltage, but this difference cancels out because they're out of phase. (Don't ask me about the maths; I tend to get lost when j or i enters the equation.) If you choose the right (or wrong?) value for the capacitor you can bring the AC impedance close to zero ohms, so the only apparent impedance would be the DC resistance of the coil. It would be fun to see whether the capacitor, fan, or circuit breaker goes BANG first. EDIT: By the way, I'm not sure if Clive intended this, but he gave us a really nerdy maths joke. The additional voltage he's measuring is on the j axis. Square root of minus one stuff. A mathematician might say it *isn't* real.

@IceBergGeo

Жыл бұрын

I remember seeing power factor correction, on the load side of a transformer (which is basically like this fan) could cause an increase in the voltage output from the transformer. It had to do with voltage vectors and so on... Been a minute since I saw it, but it's one of those things that stuck with me because of how it confused me, at the time.

Assuming the fan acts as an inductor, this is expected behaviour. You see, impedance is a complex number of which the resistance (how much the part resists current) is the real part and the reactance (how much the part resists changes in current) is the imaginary part. An inductor has a positive reactance and a capacitor has a negative one, which can be calculated and depend on the inductance or capacity, respectively, and the frequency. When you put them in series you mathematically add those together just like you would with resistances, except they partially cancel each other out. I suspect you can perform the same trick using an appropriately selected inductor and an LED lamp with a capacitive dropper, although selecting the impedances to match exactly might be a touch dangerous. You want to lower the impedance a little, but not all the way to zero. Nice demo. I always thought it was possible but I've never seen anyone try.

This reminds me of just how pointless my Polytechnic education was at times. I remember doing all the calculations for Inductive Reactance, but until watching this video I had no real idea what any of it meant. I just knew that I hated AC motors and only liked doing digital design. I'm just happy that my old brain still likes learning new things

In one word, resonance. The natural resonance frequency of the series LC circuit is moving closer to line forcing frequency.

This is a simple RLC series circuit. The total impedance Z comprises of Resistance, Inductive reactance and Capacitive reactance. Resistance is simply = R Inductive reactance = ZL = 2*PI*L Capacitive reactance = ZC = ½*PI*C Z = Sqr[R^2 + (ZL -ZC)^2] The current through the circuit is the supply voltage divided by impedance i = Vs/Z The voltage across each component can be calculate by multiplying its individual impedance by the current. Voltage across inductor = VL = i * ZL The phase angle is cos^-1 (VR/Vs)

@ianithompson4239

Жыл бұрын

Hi that's it match phase shift of the inductor and negative phase shift of the capacitor and you can get even closer to a purely resistive load, just been having to do all this for my C and G L3 8202 at college! P.s. I'm 65 now so it's most to keep the grey cells working!

@stevesteve-ei8zu

Жыл бұрын

@@ianithompson4239 Particular attention is needed when doing this to ensure that component values are suitable. As an example: If the original circuit can be modelled as a 0.16 H inductor in series with a 10 ohm resistor, on a 100V supply at 50Hz, the impedance of the inductor is near enough 50 ohms. The total impedance is Sqr[10^2 + 50^2] = about 51 ohms so I = V/Z = 100/51 ≈ 2A (near enough) Therefore, the inductor (or motor winding in Clive’s setup) only needs to cope with 2A at 100V If you add a 63uF capacitor in series its impedance at 50Hz = about 50 ohm, so when you bung the numbers in the equation to calculate the total Z it cancels out with the impedance of the inductor. The effective impedance is now 10 ohms, so the current goes up to 10A Now when you calculate the voltage across the inductor (it will be the same for the capacitor) V = I * ZL = 10 * 50 = 500V If you back calculate from Clive’s measurements for his setup with the fan motor it should be possible to get approximate values: R = 165 ohm L = 8.9 H ZL = 2795 ohm C = 1.6 uF ZC = 1961 ohm The calculated voltage across the inductor comes out a 335V (measured 330V) The voltage across the capacitor 235V

@IceBergGeo

Жыл бұрын

@@stevesteve-ei8zu that is assuming the power factor wasn't over corrected. If that's the case, your motor calc is a little off. That's the funny thing about power factor.... Unless you have at least two (technically three) known values, you cannot know whether it's leading or lagging. We already know with the motor it is lagging. But we don't know if the power factor has come closer to unity or if it has overshot it.

@CG-rr6yx

Жыл бұрын

@stevesteve-ei8zu Inductive reactance = 2 * PI * F * L Capacitive reactance = 1 / ( 2 * PI * F * C ) F = 50 Hz ( or 60 Hz, or whatever ... ).

@stevesteve-ei8zu

Жыл бұрын

@@CG-rr6yx Well spotted. We need an equation correction function. I set F = 50Hz UK mains frequency

So this is where CIVIL comes in handy. We know voltage leads the current in inductors. This means for each cycle the current will lag voltage, so every time the commutator reversed the current this process begins again. People have already pointed out how the resonance can make the circuit effectively resistive, but I it’s important to remember that putting the capacitor under load compliments everything by having current lead voltage. This means that instead of the coil having to sink current at “neutral sine”, it’s the capacitor which does so and the coil sees a constant current.

I've been using this technique for years in my bathroom and desk fans. Putting a 4µF motor start cap in series causes the fan to go nuts as you show here, but putting two in series (ie 2µF) drops the fan speed to about half. Very useful if you don't want it running flat out. This also gives the typical 3 speed desk fan 3 speeds lower than the normal speed #1 selection. Just right for a gentle quiet breeze.

Go on, see how long the fan lasts running like that.

@triodehexode

Жыл бұрын

Pop it!😊

I think you're hitting some sort of resonance. I've seen something similar happen when tinkering with the crossover on a pair of loudspeakers I had. I swapped a cap for an "audiophile" one of the same value and they became completely unlistenable. A loudspeaker designer friend of mine said it was probably some kind of resonance in the circuit.

@westelaudio943

Жыл бұрын

If the value is the same, that should not happen, except if the old cap had high ESR and the speaker was designed with that in mind... More expensive doesn't always mean it works better.

It's a RED capacitor and as we all know red makes things go faster, cars, noses (pink noses do not run as fast as red ones) fire trucks (because they NEED to go fast) and even London double decker busses (although I could be wrong about the last one!). If you want to make the fan go slower use an environmentally friendly GREEN one. I hope this was of help to you.

We're all fans, Clive. That's why we're here. 😁

Sounds like the cap and motor inductance are resonating at 50Hz

It's a classic Voltage Multiplier circuit. We used to build a lot of different multiplier circuits for high voltage low current power supplies.

@stargazer7644

Жыл бұрын

It's an RLC filter close to resonance.

Thanks for both video and educational comments

Nice demo of forming a series resonant circuit. There is a boost in peak voltage & the meter being a cheaper one shows that instead of a more expensive one being capable of showing true RMS voltage. Normally an AC motor will not speed up unless the frequency of the input increases but this one probably having bad regulation was always being under driven for the frequency so had much slip, until the peak voltage is increased.

My digital brain wants to guess that the cap is cycling and adding a ripple to the frequency. I fully admit that I don't remember much of what I learned about analog electronics. It was decades ago and I have rarely had the need to even think much about it. Your presentations are what I use to try to recapture what I lost so many decades ago. Thanks for challenging my brain.

Nice one, Big Clive. I would not have thought about experimenting with a series capacitor. They are of course used in capacitor start & run, split phase motors, but I assume that this fan is a shaded pole machine. Most of the previous comments have suggested resonance and that was my thought also. A pity that my mobility scooter is only 24VDC, or I might try a turbo boost on that!🤣

Whao Big Clive is stumped 😁 never expected that 😊

@bigclivedotcom

Жыл бұрын

Not stumped. Just surprised to run across the effect in the wild.

The capacitor-inductor combo in series creates a resonant circuit, and you just happen to have a value of capacitor where you are close to resonance and both the motor and capacitor are experiencing higher AC voltage than what is input. They are close to out of phase though, so the average instantaneous voltage is still the input voltage. The capacitor negates the effect of the motor inductance at resonance because both reactances end up 180° out of phase, and if your capacitor or the frequency actually did achieve resonance, you would blow that motor in seconds because all you have left is the DC resistance of the coil, which is much lower than the inductive reactance/impedance at 50/60Hz, and possibly overvoltage both motor and capacitor... Just like resonance can break glass. A small enough capacitor would of course restrict current flow, and a much larger one would have little effect on the motor.

Very interesting case indeed. In India we use ceiling fans (PSC type induction motor). Fans are around 60-80 watts with PF nearly 1 & use regulator to control fan speed. It was resistive/inductive type in the past. Now capacitive type regulators are used. Two caps of 4.5 and 1.5 microFarad (MFD) are used and a combination is used so the highest is 4.5+1.5 (both parallel) 6 MFD and lowest 1.5 MFD is always in series with fan motor. I have never seen voltage gain for any speed settings. Voltage between fan terminal is always lower than line voltage unless it's highest speed. That's how capacitive regulator works where capacitor works like equivalent dc resistance but without heat dissipation (ideal situation). But I have experienced similar strange phenomenon before. I had a pedestal fan (PSC motor) that has induction coil (choke coil/auto transformer) type regulator. Speed 1 is lowest and have highest L value if I add the capacitive regulator in series with highest C value the fan speed increases. That means at 50 hz 4 pole PSC motor runs at 1100 rpm at speed 1 but runs at 1250 rpm if I add a 6 MFD cap in series with the regulator. Fan has full speed 1350 rpm at 240 V (PSC motor with slip at rated load) but if I add a 6 MFD cap in series speed drops to 1150 rpm. So definitely an induction coil and capacitor in series boost voltage , but a PSC motor (power factor is almost 1) in series with a capacitor doesn't have such effect. So your motor is important here. It's not a PSC motor. I can see the PF is 0.6 so it's a shaded pole motor i.e an induction coil. So with a capacitor in series it becomes a L-C circuit and it starts to resonate ( standing wave?) and input AC combines with it to increase voltage? In PSC motor another interesting phenomena occurs. A PSC motor has two sets of coils one is primary coil connected across mains and another is secondary coil connected via a capacitor. Voltage across primary coils is mains voltage but the voltage across capacitor and neutral is higher than mains voltage and that voltage increases if you increase the capacitance value. Initially I thought that this is the back emf of motor and since motor speed increases with capacitor value back emf too increase. But it's not that simple, now I think there is similar phenomenon like your experiment. Waiting for your insightful explanation.

This is wild, looking forward to a follow up.

My first thought was the capacitor filtering out some kind of PWM signal used for the fan. Now however I clearly see this is far more involved. Fascinating reading all the comments!

@ShimrraJamaane

Жыл бұрын

Also, no PWM circuit component. Just hot and neutral wires.

Countering the inductive part of the load and bringing it back closer to unity.

The capacitance is operating in the FM band. Fricking Magic!

I'm half-way through fitting one of those capacitors in series with the mains feed to my house. It's gonna make *_all_* my appliances better! 😁 🥳🥳🥳

You reinvented the run capacitor. good work. lol

Nice demonstration of power factor correction going on here!

I’m gobsmacked 😮 how is that happening 🤔 nice one Clive

I think it's a part of the way that power is measured vs how it is actually stored or flows. The power directly from the source would have a waveform from when it was generated that would alternate rapidly or pulses, this usually can be seen in lower quality generators and alternators, the measurement devices cant read the wave or pulse only the flow, so adding in a capacitor or some way to break up the wave or pulse will allow it to flow smoother or more power to be accessible to the motor as needed since there is a greater need for power during acceleration and maintaining then there is for idle. I would try this again with a battery powered system to see if there is a pulse issue with the power system used to run this setup. Good luck i hope you learn plenty, electricity and motors is a deep hole, and i suggest looking into an "electricity 1-7 book"

This happened to me on a projectionist's splicing table that was illuminated by a 220 V filament tube. When I replaced it with a fluorescent tube (this was >20 years ago) it just said POP. Turned out that a clever engineering student had dimmed the light by putting a cap in series. And of course the fluorescent tube had a reactor inside to do the same thing (limit the current). Turned out they were cancelling each other out, reactance-wise. This was how I first met a capacitive dropper.

Also could be something to do with the shaded pole motor that the fan in question uses. Possibly the same thing that happens to capacitor start/run motors with the phase shift. It would be interesting to see what would happen if the capacitance was changed from a smaller one to a larger and or larger to smaller.

It reminds me of when I powered a boost converter by plugging it into to an RV's 12v outlet and all the lights in the RV got brighter and the fan went faster. Turning the output up made the circuit voltage throughout the RV increase. No load was placed on the output of the boost converter. My guess is this fan and capacitor is doing something to reduce the impedance of the circuit while storing energy and then dumping the stored energy, all in sync with the phase of the motor.

you're correcting the power factor and "resonating" the inductive load.

That must be one of those fancy Flux Capacitors 😉

I Reckon it's about the resonant LC circuit you just created! :)

Electrical Technology, Fourth Edition by Edward Hughes (Brighton College of Technology). Also known simply as 'Hughes'. SI Units in the 1972 edition, cost me the princely sum of £1.50 and I went straight to chapter 11, 'Single-Phase Circuits'. Best textbook I ever had and I'll not be getting rid of it 👍

Source is AC so current goes forwards and backwards. That cap is non-polarized, so it can charge on either plate. As long as current is flowing in one direction, the associated plate is charging. As soon as current reaches the reverse, discharge across the plate occurs. This happens really fast, which causes a massive current and voltage spike. Then it happens again in the reverse direction.

Fully agree to most of the answers - it's a resonance effect. To confirm or bust this idea try to meassure the inductivity and calculate F(res) = 1/(2 * Pi * SQRT(L*C)). Alternatively use a sInus signal generator and an additional series resistor to find the resonance frequency of the fan/capacitor circuit. Search for the frequence with the minimum voltage on the series resistor. Your voltmeter is good enough to find the dip. I would expect anywhere in the 20 to 100 Hz-range. Regards

Many years ago, my mother's stove had issues with the shaded pole motor driving the door lock stalling and I fixed it by calculating its inductance, then using a 2.7uF series capacitor to power-factor-correct it. Same thing here, just look at the PF.

I'm glad you didn't get sucked in!

Resonance, which is why all the capacitive fan speed controllers I have taken apart use values over 2.2uF, so as to get on the other side of the resonance peak, and have a lower voltage across the coil, so the fan power is reduced, causing the slip to massively increase and thus lower speed. Normally a 4 position switch, first off, second full voltage, then third a 4.7uF capacitors in series with the motor, and fourth a second one in series with all of that. Makes it simple, you only have a single pole switch, and a single 1R 2W resistor in series with the common, and then just have to have break before make contacts on the switch. 400V pollyputthekettleon capacitors times two, and a small PCB to hold the lot, and some screw connections to put in series with the fan. Failure mode is always speed 2, or the switch wearing out.

Congrats, Clive👍 You just built the worlds cheapest boost converter utilising the resonance from the inductance of the consumer🙂

Lol reminds me of when I was little, and thought I could safety-ballast a transformer by a primary series cap :)

You were certainly correct to shut down that little experiment quickly. As these types of cheap motors are generally manufactured with very little headroom above stated normal running specs allowed for it probably wouldn't have been long before the dreaded sight and smell of smoke did occur with the resultant failure of the motor to function as per normal. The power consumption was about 40% above normal operation which generally leads to quite sudden motor failure by itself. The fan was definitely pushing through more air so that power consumption of the motor was real. Another factor that would also have contributed to the motor windings failure is the much higher voltage across the windings. That 305 volts (if I remember correctly) was an actual PD no matter how it was produced, and the winding were almost definitely not designed for that high voltage. Therefore there would not have been enough iron in the magnetic path and the the extra voltage would have oversaturated the iron at the voltage peaks causing massive magnetic flux distortions that were definitely not sinusoidal thus becoming another major source of heat and inefficiency within the windings themselves. Many of the responders tended to see the motor as a simple inductor or represent it that way as a simulation. This is an extreme simplification that has very little relevance to the great variance of loads and conditions that a motor, even a simple one like an exhaust fan, might be subject to during its operation. If it was that simple then all exhaust fans or similar would use a suitable series capacitor to some extra performance at little cost. My expectation of why few motor designs use a form of series capacitance to increase voltage across the motor coils while adjusting the motor coil design parameters to suit is that motor starting torque could be severely reduced and motor speed stability under varying loads could also be severely comprised if implemented.

Found it strange when I opened a standing fan my friend gave me the other day. If i remember right it was an Ikea one he got from a clearance that had stopped working. That too has a decent size and voltage capacitor which was in series with the fan. Thought it was strange not to see a diode but instead a capacitor and now hearing about it increasing the power factor it makes sense.

Oh this is much better! Yeah it might be smoky after a while, but check out that airflow! I reckon this would be the ideal option for the fart sucker after taco night.

Yes, there is phase shifting. Why the higher current? Where F=freqency C= capacitance, L=inductance Xl=inductive reactance, and Xc=capacitive reactance, then in ohms Xl=2×pi×F×L, and in ohms Xc=1/(2×pi×F×C) Lastly where Z=impedence in ohms, R=resistance, Xl=inductive reactance and Xc=capacitive reactance, then Z=sqrt(R²+(Xl-Xc)²) in ohms. If the capacitor and inductor are in resonance at line freqency, the resistance because of reactance Xl-Xc = 0, and conseqently the impedence Z then equals R, which let's more current flow than without a serries capacitor where in ohms Z=sqrt(R²+(Xl-0)²).

Series resonace of an LC circuit where the impedence dips towards the DC resistance of the coil, so the current and voltage in the coil and capacitor increases. If you tweak the capacitor to get closer to the resonance it will get more extreme.

Basically the only new principle involved is that instead of power being generated by the relative motion of conductors and fluxes, it’s produced by the modial interaction of magneto-reluctance and capacitive diractance. The original circuit had a base plate of prefabulated amulite, surmounted by a malleable logarithmic casing in such a way that the two spurving bearings were in a direct line with the panametric fan. The main winding is of the normal lotus o-deltoid type placed in panendermic semiboloid slots of the stator, every seventh conductor being connected by a non-reversible tremie pipe to the differential girdlespring on the ‘up’ end of the grammeters. Moreover, whenever fluorescence score motion is required, it may also be employed in conjunction with a drawn reciprocation dingle arm to reduce sinusoidal depleneration.

Big Clive accidentally discovering resonant tank circuits and pissing of the ELF communit all at once. 😁

Definitely run it like that, the power factor is much better!😜