Mr. Spiess: Beautiful but... your Power Factor formula at 17:57 is wrong. It is not P/Q but, instead, P/S. Power Factor is the cos(theta) and the closer to 1, the better.
Indeed, Mr. Spiess. As you know, we, the machines, must obey the Law Zero of Robotics/AI, "Thou shalt not divide by zero". I must say yours is a great channel with great and very well done material, which by the way made me to be your subscriber. Thank you for all the videos you've published so far. They've really helped me to upgrade several of my systems.
The "One hand rule" was the first thing we learned at school. Seeing it in this video, also as first point, show how well educated and well versed Mr Spiess is in Electricity and Electronics.
Was told to brush the back of your hand against metal cases - if it was energised your arm would retract away from the danger If you grip an energised circuit you cant let go
I appreciated seeing that rather than a vague "this is dangerous, don't do it" statement that covers the video host's arse but would be ignored by a lot of viewers!
I was trained as an electronics tech by the military in the 70's, and was taught the one-hand rule too. We were also taught to not wear watches or rings or dogtags for fear of them shorting stuff out. This was on aircraft which used 110VAC 400Hz power.
from what i remember from my tuitions, power factor can be corrected by using capacitors of the right size on the mains wires. However there's another neat trick : if the mains are 3-phased, and the power factor is similar between all 3 live wires, the power factor can be corrected using a synchronous AC motor (yes, synchronous, not asynchronous) that runs without load. It'll probably heat up, but the motor ends up consuming the bad power factor just as capacitors would.
It is called a synchronous condenser. On a synchronous AC motor you can vary the amout of reactive power consumed or produced by changing the DC voltaged applied to the rotor.
As an electrician mainly working in commercial settings (3 phase here) I am extremely jealous of your 3 phase residential power! Sometimes the single phase (one 220v phase split to 2 110v legs) we have for residential power is very annoying! Very interesting video, btw. Thanks for all you do for us out here in TH-cam land!
Thank you very much for making such videos, which helps not someone who learning electricty from 0, but jump-starters and diy-ers who started w/o advanced/deep-basic knowledge in electricity!
Hi Andreas. Excellent and accurate explanation. In Italy only those who request a three-phase contract receive all three phases: the energy meters are simpler and less expensive (from corridor whispers they should cost less than 40 euros each to the energy distributor, considering that in Italy only for E-distribution we talk about 33 million meters, three-phase and single-phase together ... with a hundredth of difference each we make a good figure. I have seen that in Germany, the only country where I have been able to see a home meter, instead they carry three-phase electricity also in homes, I don't know in the rest of Europe. Here in Italy, at least years ago, before the liberalization of the market, (Enel was a non-profit national body, but in fact it was a monopoly) the customer who wanted a three-phase contract in a civil home had to sign an indemnity on the dangerousness of the voltage at 400V. In all cases, the distribution lines are all three-phase at 400V, with the same cross-section of cables it transports twice the power compared to a single-phase system, but the derivations for the individual supplies (we could improperly call it the last mile) are all single-phase to exception of those who specifically request a three-phase supply
Thank-you Herr Eng. Spiess for all of your great videos. Your information is always accurate and very professionally presented. In North America, houses do indeed have a 120/240 V split phase system that work well. Large apartment buildings often have three phase systems with 120/208 V, using the phase voltage to create 208V rather than 240V. This is annoying as kitchen ranges and clothes dryers meant to work on 240V are now operating at 208, which delivers only 75% of the expected power.
You missed one important detail. 208V, 3 phase, 4 wire power (3 phases plus Neutral, what you call 120/208) is used here in Canada and the USA in apartment building and factories because you can run 3 phase motors for booster pumps, HVAC units, and industrial equipment AND 120V outlets (from any phase to neutral) from the same transformer and breaker panel. Industrial motors here are usually rated for 220V because 208 and 240 both fall within the +/- 10% voltage tolerance. So, while it is inconvenient for your 240V appliances it holds major cost and complexity savings for the electrical systems of the building.
If only I'd seen your video 18 months ago. Caught out by measuring voltage and current across different phases. Data looked correct but power consumption was too low compared to the bill. Turns out the electrician that did the install of 3P meter had an off by 1 error with the voltage feed on the 3P bus bar. Took me a while to figure that one out. This was using Schneider Electric measuring gear. Quite accurate but expensive. Great work as always.
When looking at RMS to DC converters, it good to look at how well they respond to the signal "Crest Factor" which is an indicator of how close the signal being measured is to a sine wave. e.g. Crest factor is a parameter of a waveform showing the ratio of peak values to the effective value.
In the UK we normally ONLY are supplied with a SINGLE phase supply. The three phases of a local final transformer are shared as equally as possible between multiple houses. e.g. the first pair or first two pairs of houses will be fed from one phase, then the next group of houses, then the third group from the other two phases Some households MAY receive a three phase supply if it has been requested (and approved) from the distribution company. This may or may not be the same company who bills the premises (more commonly not). If a business is being run from home premises that requires three phase, quite often, depending on the area, the local council will be told and business rates applied to the premises! That is AFTER they may take you to court for unlawfully setting up a business without gaining planning approval first!! Smart meters in future will almost certainly start charging (and more costly charges!) for reactive power since it causes current loading problems for the localised grid area - the reactive (but REAL) current can exceed the local capacity of the grid cables, hence requiring more expensive infrastructure. This is "partly" due to the massive increase in non PFC compensated switch mode power supplies in homes driving SELV (low voltage) LEDS. It is also complicated by the increase in solar PV usage WITHOUT the relevant storage of the excess which instead goes straight back to the local grid.
We will see what happens. Here often the energy is not much more expensive than a fixed price for the network. And I assume pricing will change if people more and more start to produce their own (peak) energy...
There are 2 reasons to measure AC mains. 1) Because there is a need to know how much power is being used. 2) To know *IF* power is being used. This video had great information for case 1. But, what about case 2 ? True, if the answer is available for case 1, then case 2 is known. But, case 1 is often more complicated and more expensive. What about a simple cheap solution to case 2. But, you may ask, why be interested in only case 2? For example, a microcontroller can be used to mimic the IR input to a lot of IR controlled devices, like Air Conditioners, TVs, and a lot of others. Unfortunately such a device does not give good feedback to the microcontroller, so the microcontroller can't know if sending the "cycle power" command worked and actually turned the device ON or OFF. One way the microcontroller can know if the device is turned ON or OFF is *if* the device is using power. Exactly how much power is of much less concern, maybe only that the ON state is a lot more than the OFF (or standby) state. Here is a simple solution that i used which is protected from mains: In a video #321, "the guy with the Swiss accent" mentioned some current sensors usually built off of the Allegro ACS712 hall sensor (or something similar), which he rightly discouraged for use with mains - at least as-is. Only with luck will that chip work with mains. And relying on luck when working with mains is a quick way to posthumously earn a Darwin Award. Since that chip is only rated for a working voltage of 100v - sending 120v of mains AC through it might work, but it's not a good idea; And if your mains are 240V... that's almost 700v peak-to-peak and not to even be thought of. However, that little chip (or any similar chip) can be coerced into working with mains very safely - although it comes with a loss of accuracy. Again, if the real question is *IF* power is flowing, then accuracy is not very important. Here is what i did: I took a large eye-hook screw (4cm or 1.5inch diameter) that a magnet would stick to (stainless steel is not good) and sawed of the screw part, this left an iron loop with a small gap where the loop comes together. Then i wrapped some heavy gauge insulated power wire around the metal of this loop. Starting from near the gap i wrapped a spiral around the metal until it got to the other side of that small gap - i got 25 tight turns. Then i used hot glue to place one of those the hall-effect sensor chips into the center area of the gap... you want the gap just big enough to fit the chip without damaging it. Power from one line of the mains goes through the heavy duty wire in the loop. If the wire used is designed for use with mains power then this is as safe as any extension cord since the mains power is completely isolated (as long as the insulation does not melt). And now the microcontroller can read the hall sensor to see if there is current - and if is current flowing then power is being used. The reading is not exactly accurate - as particularly at very low current flow there is a fair amount of noise. But since the difference between stand-by and someone actually using the microwave oven is really huge, my microcontroller can easily tell if the microwave was turned on. On the software side, the program must be aware that this signal is AC and switches from positive to negative flow 50-60 times per second. I have mine probe as fast as possible for 200ms and average the absolute value of the results. But that is a whole other discussion.
In the US we do have 3 phases but that is typically industrial although a residence can have it if it is available at the local distribution point, is needed and requested. Residential customer might have to pay for that in fracture to be installed up to a point and the voltage on each phase is 208 with respect to earth/neutral/common. The two phases you talk about is simply single phase coming down the local transmission lines [2 wires/14KV] to a transformer that puts out 240V with a center tap that is used as neutral to reference 120V off of each line. This way it is single phase 240V and when referenced to neutral 120V using only half of the phase but still 60Hz.
Thank you for your explanation. I think I showed the "split phase" concept in the video. I named the two wires "phases" because it has a shift of 180 degrees if measured against neural which can be relevant for measuring power (if I understood right)
I built one of these home energy monitors for my split phase system using two CT clamps, an AC/AC transformer, an Arduino Uno, and Robert Wall's EmonlibCM. The latter is essential for this project because he takes all the complex calculations from an electrical engineering PHd background and does them for you, to the precise timing known on the Uno's chipset. It's also surprisingly dangerous - even though the CT clamps aren't actually touching the mains wire, if they do not have a load resistor or a TVS diode, they will explode in a big puff of smoke if you clamp them around a wire carrying 100 amps+ of current. Because with no load resistor, they will generate theoretically millions of volts. As i nearly discovered.
The Kill a Watt type meters are convenient and have become reasonably inexpensive.Two uses I find they're handy for are for checking the output of my old school generator, and for establishing an idea of how much power small appliances use.
Nice video, and a complicated topic. One thing not covered here though, don't always expect the Current waveform to be sinusoidal. Switch mode power supplies, CFL bulbs, LED lamps are all non-sinusoidal and measuring power factor, and true power is very difficult. These modules make this possible because they have delta-sigma converters and an 'algorhythm' to determine the true power. You can use the LTC1966 AC to true RMS converter to do the RMS calculation for Voltage and Current. Then regardless of the wave shape the power factor can be calculated (V_avg * I_avg) / (V_rms * I_rms). Have a look at those modules, they work really well with Arduino.
I am a retired Electrical Engineer and I found this extremely interesting and there are a few places where I need to watch again because you said something which surprised me. Power Factor correction is extremely important in industry and the supplier will shout at you very loudly (as well as charging you) if it drops low. The domestic user pays for power factor indirectly because VAR does not do any work but you pay for it. During my Apprenticeship Elec Tech called this Wattless Power. I need to look at your Oscillospcope traces again mainly. At 75 yrs old I do not need to, just curious. Thank you.
@James Goacher If by domestic user you mean residential - as opposed to commercial/industrial - then they may not be paying for reactive power. The Ferraris type meter and its electronic equivalent used in North America tally only real power.
@@kiowablue2862 I have never done domestic electricity apart from the necessary repairs of appliances. The last Electricity Meter I saw was the Eddy Current disc type. My present meter is in a cupbord outside and is a block of something with a couple of digital displays which I read remotely cos it supposed to be a Smart Meter, never understood that term. I am way out of date with equipment now because I have been retired for fifteen years from a fast moving field. I keep up to some extent but I do not need to design anything because I have no problems to solve (mostly). I am watching this TH-cam channel because of Mr Spiesss' (that is grammatically correct s appostrophe not apostrophe s) other output because I am inventing problems to solve with Arduino type things.
@James: To be still curious at 75 is a very good thing. Without that you probably would get old fast. I am 12 years younger but already see colleagues which stopped to be curious...
I have a SonOff V2 and it measured for over a year on the same walll plug the more reliable energymaster was used for. After 1 year and 500 kWh consumption the difference is below 0,4% or less than 2 kWh. Did not change anything. Since then I purchased a different model that is housed in a plug in plug design switch for 16 A max. Results are 0,5% different so not that bad to get behind consumption of a dryer over a year to see that seasonal curve if that exists or that of a washing machine or even a night light outside and its movement sensor. It is a 32 Watt fluter and used 1 kWh per month so just 12 kWh a year. Who knows what a light does during the deep night so we measured to be sure that this is not a silent or hidden energy burner. If you check each single pluged in device and also the directly grid connected pieces like window jalousies you get a good feeling about your home energy consumption and efficiency especially if you make an inventory list of all devices and its standby watt and usage and an estimated use time per day ... If you then enjoy your holiday you get behind if your standby estimation and device inventory is right or not. That makes things easier to change habits or devices ... for example a smaller oven to heat up for just a fresh bread or piece of pizza instead of the usual oven which takes kWh to heat it up before starting to cook. When do you turn of a water cooker ... if it is already cooking or earlier and what is the difference? So we measured the water cattle for a quarter and guess what: it is used far often or with more water than assumed. It uses 5% of household energy consumption ... for tea mostly.
An excellent review of the topic. I had forgotten allot of this. Power factors, RMS and needed a refresher. Very educational and you are a great teacher. Thank you.
I monkey around with various "cheapo" AC power meters and capture devices (like the PZEM-004), but in the end I decided to get "real" and purchased a Fluke 377FC RMS clamp meter (with stand-alone logging!). It's very helpful to have an accurate sanity-check to make sure that your hacked-in stuff is returning data that is meaningful. Also note that a lot of cheaper clamp meters cannot measure inductive or switched loads correctly (non-RMS).
Three phase power is used in the United States in places like almost all of New York City. The Two phase system allows for larger appliances to run on 240v compared to most other household appliances which run on 120v. This way most normal homes have 120v wiring with occasional outlets at 240v for high powered AC units, clothes dryers, and ovens. With a standard wall socket voltage of 120v, the three phase wiring would only provide 208v and not 240v. This is actually convenient in places like NY City where they don't want the consumer to be running high powered devices like electric ovens or electric clothes dryers which are, as far as the electrical grid is concerned, better powered by gas.
The other thing to note for left-handers: It's very difficult, but try to keep your left hand in your pocket rather than your right. Current will always flow through the easiest path to ground and that means (unless your heart is on the right - a VERY small minority are) then slightly more current will flow THROUGH your heart to ground from your arm down your left side. Current will still flow down your right side too but your heart is not in the way. If you receive a shock through your right arm, current will still flow through your heart, but mainly NOT and in any case will be much smaller, hence marginally safer.I learnt this over 50 years ago from an OLD TV engineer who used to have to work with 10kV to 35kV or more in CRT TVs. The bigger the screen, the higher the voltage (usually) and colour screens more than mono.
13:16 - Also as I recall if the voltage across both wires is not 0, you have a leak somewhere if you haven't noticed yet (usually it's sparkly and hot)
Thanks for the explanation of the meter at the very end. I have one of these and wondered about the watts reading when the power factor was low. I have a solar system and inverter so the power coming out of my inverter is not accurate just from the watts reading unless power factor is 1. When you explained that it should be labeled VA that makes more sense to me.
Hi Mr.andreas you show device at 9:10 . I want to detect AC mains (healthy voltage) does it do the job? I am building a device which can see whether mains voltage is ok or not. It is ok if voltage above 200v ac if it is below 200v it is not healthy phase. What do you recommend to use in this scenario?
If you want to have a signal for a precise voltage you have to use something like the ZMPT101B. The "mains checker" has no precise threshold. Maybe you can experiment with different resistors if you get it precise enough for your needs.
@9:20 What should be the distance between AC and DC? Arent optocouplers made to withstand 2kV'ish+ volatages? Or the typical pcb not suitable for such clearance?
@@AndreasSpiess Thanks for the reply. I guess a slot can never hurt and is overall a good practice. But if it was only about the distance then manufacturers would've surely used a bigger case for the optocoupler I guess.
Great video as usuaI. I also share your concern about connecting to mains. It's great that we now have smart plugs with built in monitoring but I wonder about the accuracy. For constant loads directly connected to the panel, it might be easiest to read the nameplate or use a Current probe with your multimeter. Then monitor when the load is switched on. For variable loads (like my heat pump) I thought about the AD8210 Current sense amplifier and a current transformer and burden resistor. Current transformers are evidently an accepted practice. My solar panel installer put one in my panel.
Can we masure house consuption end send the values via mqtt to Raspbery with Shelly device(using modify firmware)? Or with an Esp 8266 + CT? A new video in this direction will be very halpfull. Thank you for all your work!
Hello Andreas, thank you for another brilliant video and all the work you do on this channel - to start with. Concerning the measuring device shown at 23:22 - I absolutely do not understand the wiring diagram on the website. Could you please explain where to connect L, N and the leads to the load to these four connectors on the device? Must be a mental hickup... Thank you!
@@AndreasSpiess UK has 100Amp main fuse so probably just different ways to share the power out. US definitely needs more than one phase for running cookers and heating, 120V would need a lot of copper for the current. UK is Europe, just not mainland ;)
@@matteopascoli It's being metered in each house. Anyone can get the phase installed in their house if they want but unless your running heavy machinery it's not really required.
Both AC/DC voltages and Currents can be measured safely (isolated) using chips like ACPL7900 or equivalent. They produce a differential voltage in proportion to input voltage or current.
The yellow Metrrixx multimeter has the state of an old Nokia cellphone. Always reliable, tough and still working after dropping from the ladder. Only changing the mA fuse from time to time and a battery every year (if you did not forget to switch it off) 😉
14:45 About CT by clamp to Neutral wire, but if your wire (line) of my house is Live (Hot) 1/Live (Hot) 2 wire from DU (220V 50/60Hz). How can i use this CT?
Power factor is a big problem for those current transformer devices that are sold to be clamped around the main tails to/from your electric meter in order to report the consumption of the whole house, even when the installation only has one phase delivered to it, as is the case for almost all UK houses¹. The ones I've used don't measure the mains voltage - *at all*, let alone in tandem with the current - and yet they report power rather than current, so presumably they're just assuming a mains voltage of 240V RMS and an arbitrary power factor?! I've used three such devices - the Energenie Mi|Home MIHO006, the Loop electricity monitor, and the Owl CM160 - and they all reported power consumption figures that were *significantly* wrong: in the region of 30% out! They each reported different figures, too, so it seems they're using different assumed values. If the difference was only 5% or even 10% I wouldn't care nearly as much, but 30% is unacceptable, IMO. The mains voltage here (as measured by a couple of TP-Link HS110 devices and imported to InfluxDB+Grafana) has ranged from 230V to 245V over the past month, so even assuming that to be constant introduces some amount of error... These days I'm using an ESP32 and a phototransistor to measure the duration between the flashes of the red LED ("1000 imp/kWh") on my electricity meter, very similar to the system described here: esphome.io/cookbook/power_meter.html (though I'm using ESPHome's "pulse width" sensor, because ESPHome's specific pulse counter implementation means that the more frequently you want it to report a value, the less accurate its readings get, to the point that, with a report every ~10 seconds, I had a *resolution* of around 400W!) This method is very accurate - it matches what's displayed by my utility-provided smart meter's in-home display - and since it uses the meter's own measurement hardware, it doesn't have to worry about the power factor - it would even automatically switch to reporting VA if my supplier decided to start charging me for apparent power, as Big Clive suggests they will! ;) ¹ Which will itself become more of a problem in the coming years: 60-100A at 240V [14-24kW] has been plenty for most households so far, even with a 8-12kW electric shower, but having e.g. an electric shower *and* an EV charger can create problems - both practical and regulatory - and 3-phase makes faster EV charging more practical as well (not that it's needed for most people)... But I don't think even houses being built in 2020 have 3-phase supplies, sadly... ² Energenie: energenie4u.co.uk/catalogue/product/MIHO006 | Loop: www.amazon.co.uk/dp/B00YNCJB3S | Owl: www.amazon.co.uk/dp/B004BDNR84
I do not know the power meters you used. But it could be that they cannot measure "true" RMS. It would also be interesting if it is only a calibration issue or a random error.
Can you also access the data from the power monitor with the display (called P06S apparently)? I didn't find any information about a serial interface like the PZEM-004T has. Would be nice to have a display and broadcast the data.
This seems similar: hackaday.com/2016/07/11/put-a-reverse-engineered-power-meter-in-your-toolkit/ So not that easy to do safely. Also, some versions are not STM32-based.
It's an older model of this one I think: www.banggood.com/MINI-DS213-Digital-Storage-Oscilloscope-Portable-15MHz-Bandwidth-100MSa-or-s-Sampling-Rate-2-Analog-Channels+2-Digital-Channels-3-Inch-Screen-With-Logic-Trigger-p-1412378.html?rmmds=myorder&cur_warehouse=CZ
I loved the video and how it is presented. Very practical and of great didactic contribution, a pity not to have seen it until this 2022! I just found your channel, you already have one more subscriber.😉
This video was extremely useful!! I am in the process of making a datalogger with Arduino and also exploring different methods to connect to mains and DC powered devices. Thanks.
Great videos! This one and 321... Working on a project that will turn on and off a load of less than 5amps at 110v... Want to include power monitoring and I am using acs 712 for now... For this application what would be the advantage of a more complex solution as the ones you presented here?
Here's an interesting question... How would you go about monitoring actual high voltages? ...ie electric fence voltages (~10kV, ~150mA, 1Hz ...but with short duration soliton pulse) I made a few Lora fence monitors and am using basic voltage dividers. Looking for a more robust solution measuring voltage using opto isolators though.
I do not know. Maybe with a parallel wire and a resistor? You should get some energy "transmitted". Or a simple radio receiver with an antenna. There you should easily hear the sound of the voltage spike. I would not connect resistors to the wire itself because it can reduce the maximum voltage considerably.
Get an inductive pick-up off an old automotive timing light. The pickup clamps around the spark plug wire and fires the strobe. A simple interface to the pick-up will detect the short duration high voltage pulse.
Could you please assist in testing current of PCB tracks. I have a problem where I have a short on a pcb and need to track it down. I have been told there is a probe that will show the magnetic fields on pcb.
In Germany many old electricity counter are now beeing replaced by digital ones which offer an I/R interface to transmit the data. Also common gas meters offer the possibility to read the data via a reed contact. I've seen several videos on how to monitor gas and electricity by that means, but none of them reach your quality. Just a nudge...
You are right. I also saw some videos with the ESPcam. In our house we have a central distribution and the counters are not in every home. So I have no way to test it. But I installed an Shelly 3M and I am very happy with it. Like that I immediately see which phase (and which device) uses the most energy.
Good stuff! Any recommendations on AC current meters which output a DC proportional voltage? This would allow the ucon to do other stuff and just read at any time.
Major reason for AC in power comes from transmission in the old days. AC can be transformed to hundred of kilo volts to reduce current and hence transmission loss. Not possible in the old days with DC. In modern time it is very different. If we needed to design this today we would select all DC. With modern hight power switching electronic DC can be transformed up and down in voltage more efficent than AC. Som of the large power distribution companies are planing to provide DC power to private households. It is a very long plan is it is not easy to change now. But the saving will be large in reduced power loss. In an transition periode we will get both AC and DC. Already several decades ago power transmission was often DC to reduce the loss that comes with AC due to induction issues generation surface effects in the cables.
Thanks for your info. We have ABB here who are quite involved in the highest voltage transmission ( or was. I do not have the actual situation what still belongs to them). Here we also discuss DC underground cables because it is nearly impossible to build new traditional lines anymore. And DC fits well with solar power.
the assumption is that the AC is a true sine wave which, as you pointed out, may be far from true. Using a uC one ought to be able to calculate the actual area below the curve (by slicing) using Riemann Sums or the Trapezoidal Rule
I do not know how they do their RMS calculations, but I assume these chips or the Arduino library I used use one of the concepts mentioned by you. The dimmer showed that you are right with the sine...
I assume with a small resistor and an oscilloscope. Maybe you can replace a resistor with a hall sensor shown in this video. But you have to check their max. frequency.
Great video, but I still don't understand how AC power usage can be measured, if there's a constant volt going backward and forward won't that voltage be constantly be replenished and if so how can what is used be measured if it's constantly replaced. Baffled. Thankyou for the information though. Stefan
I always look forward to your videos. so professional and informative! do you have a recommendation to measure mains power before the mains breaker? There are occasions when city power is down and i open the mains breaker to back-feed a generator power to the mains panel. i would like to monitor when city power is restored. My intention is to find a suitable sensor to monitor one or both 240 mains cable in the power panel. I understand the a cable clamp is used to measure current, however, since the mains breaker is open and voltage is present from city power, no (home) load is connected so i assume zero current. can a current clamp be used to sense when the city power is restored? I would like to measure any voltage activity on city power and have an Arduino trigger a relay to provide an audio indication, then silence the alert. what contactless/clamp sensor would you recommend? I release you of ALL liability when answering (thought i would add this for your protection). Keep up the OUTSTANDING work, Sir!
I have no knowledge in wiring such distribution box. You have to ask somebody who knows much more. You can use the clamps whenever you have current flowing through a wire.
Ironically most modern power supplies are switch mode and have to convert the incoming AC to DC first , DC transmission is more efficient but the technology to convert between voltages at DC wasn't available back in the Edisson/Tesla years so AC was the better choice but now DC would be better.
I want to put a power monitor for the apartment in my fuse box and publish via mqtt. The FI seems to be only 25A. What's the best choice for accuracy+speed (want to try to detect different devices by their power profile like sense.com)? I have a PZEM-004T with a 100A CT but haven't put it in yet. How much more accurate would a 30CT coil be? Are the CT versions just safer or also less precise? What about a Sonoff Pow R2? It seems to be only 20A, but I guess that'd be enough. What happens if it went over 20A? Many questions :)
If you want to have a more accurate measurement with your PZEM-004T 100CT, and your max current is less than 50A (in most of the cases true for residential houses), then you can make 2 rounds with your source cable in the CT coil. I you do this, then you will use the PZEM in full scale (0-100A) but then you need to divide the result again by 2 off course to get the correct value.
@@svdhallen Thanks. That would be easiest, but the wire is too thick and also too short (and hard to access - since I'm renting I don't want to rip the box out of the wall). The PZEM-004T claims 0.5% accuracy - does that mean 0.125% accuracy for a 25A CT? I'm confused by the use of percentage instead of some constant like for the resolution.
How could I measure real time power on a 3 phase system. I saw I could use a 6 channel ESP energy meter. Because I wanna do it with ESPHome and homeassistant. But I dont find that board here in germany (Shipping is very expensive ) What would you recommend me ? Thank you !
I have 7 24v thermal actuator heads. If I had 24v transformer at 1amp, would that be sufficient to power 7 thermal actuators at once, or any combination of the 1-7 powered? Low energy input approx. 3W - 3.5W. • Breakaway current: 0.35A (24V) • 24V can be supplied from either an AC or DC source. • Coil resistance: 24V: 115 Ohms +/-29
Max power consumption looks like: 7*3.5W = 24.5W. Your transformer is 24W (24 volt * 1 Ampere). So you are a fraction below, but I would give it a try, or to be safe go one step up in transformer power.
You have to do your calculations. 24 volts is ok. But you also have to take into account the max. current all actuators will draw. Of course the transformer must be capable of sourcing also this current. 1 A is sufficient for max. 3 actuators (3x350mA).
@@AndreasSpiess Thank you! Yes I was confused by the documentation for their official wiring centre. It said that "With its 50 VA transformer, the 24V version allows up to 16 x 3W electrothermic heads to be controlled" which is 2 amperes, so with only half I calculated at 1 ampere for own setup. It does say later in the docs that their is 4A, transformer protection. Ref EWC-1: emmeti.co.uk/wp-content/uploads/EWC-Wiring-boxes-technical-Product-guide-April-2016-V2.pdf
I'd like to know if there is a device that will tell me if I am feeding power to the grid or drawing power from the grid. This is to use excess solar power in water heating and battery charging. Is there a device that will tell me this? (Or do I have to build something to detect phase of current/voltage and then work it out from that assuming I don't have a motor running that will skew those results)
Hi Andreas Is it possible to use PZEM044T for three phase(ac) power measuring hooked with an arduino? Am Working on a diy project for measuring 3phase current & voltage for a 240AC motor. Any other better ideas too is a welcome.
I use a Shelly 3M. It should be possible to do it with single Phase systems. But the voltage sensors have to be at the same phase as the current sensors
Sir, am making homeautomation project based on ESP32 and relay module, project is properly worked. But i don't understand which protocol used. As per my knowledge HTTP protocol for WiFi networking. Am i right sir ? And second question is relay module connect to ESP32 through 10 wire so what is the protocol for this type communication ?
1. You can use different protocols over WiFi. I use MQTT. I would Google "Tasmota." 2. Each relay is usually controlled by an ESP32 pin (and a transistor). No protocol is needed other than on-off.
@10:33 "Everybody can do sine waves." - I beg to differ. Transcendental waveforms are _the_ most difficult ones to generate. In the digital domain, at least. ;P (Did some research on this matter in a previous life)
good job. I learn a lot with you. I have two questions. In my house I have 2 different lines, one with solar off grid and another normal electrical grid 230v in Spain. The problem comes when by mistake, or by failure in one of the relays of the electrical panel, some cable is attached from one line to the other. Then in the inverter the transistors explode. Is there any way to protect the off grid inverter so that it stops the moment it detects a different line? The second question is: I use relays SSR-40DA, to commute between solar line and normal line, when the voltage in the batteries is low or some sensor drives the change of line. ¿HOw i can protect the thyristor on way out? If the thyristor is in short , what sensor i can use to drive it to stop the inversor. I can send you photos is you want it.
Have a look at Victron solar chargers + inverters, not cheap, but do what you want and no more exploding transistors or SCR resulting in loss of power.
@@rolandleusden You are right, but victron is not affordable for my, although there is other brand cheaper than victron that I could use. In general, I'm not very friend of all in one, because it normally are expensive device and complicated to repair, and when you have a failure and your are not able to fix it, you'll lost a lot of money, and loss of power. However, if you use individual, well-kown and cheap modules, possibly you are able to fix it, and the repair costs will be very cheap and at least you can use some module independently. It's true, that you don't have to complicate, if you use this kind of all in one. Perhaps, it is the moment to change my mind and I must extend the installation. Thanks.
@Carlos: I have not a lot of know-how in this area, so I am not a big help. High currents and high voltages are a very different area to where I usually work. This video is more or less what I know :-(
An oscilloscope that isn't earth referenced must have all its channels isolated from each other (both signal and ground wires of the probes). Generally amplifiers, signal generators, power supplies, etc are all earth referenced. Any floating voltage connected to the ground wire of the probe will cause sparking and damage the equipment. Battery scopes do not face this problem, neither do power scopes as they use isolation transformers
I learned now about the other channels. This problem exists also with my battery powered oscilloscope and I was not aware. Maybe because I usually only use one channel with this one. Now I even pay more attention....
@@AndreasSpiess people in the home automation hobby do like to mess around with these things but they usually don't go the full DIY way, so pzem is the bare minimum with a wemos and you easily integrate energy monitoring in the home automation system.
Seems to be a quite complex system. Here only the railways use a different frequency (16 2/3) because early motors had more power during start with lower frequencies.
@@AndreasSpiess Well, I found out. Your device doesn't correctly display the voltage. Your leading edge dimmer lowers the effective voltage by using only a part of the sine wave of the voltage. Your measuring device states 233V nonetheless of the dimming ratio. Did you maybe accidentally measure the input voltage (before the dimmer) instead of the output voltage (after the dimmer) with this device? A resistive load keeps a resistive load even when dimming and therefore power factor is always 1,0. Either you have accidentally connected/measured something wrong or the device is displaying wrong values.
If you watch other videos you see the same behavior. But your point is interesting: What happens if you connect the meter before or after the dimmer. The RMS power should be more or less the same... (The dimmer does not get hot). According my knowledge, the power factor has to be measured before the dimmer because it is measured for a whole system.
@@AndreasSpiess Then these videos are totally wrong too! What you want to measure is, what your load (in this case your light bulb) receives not what your dimmer receives. The dimmer always receives the full sine wave of the voltage. Via fastly switching every half wave it then regulates the voltage your load receives. So your dimmer sees the full voltage, your load (light bulb) does not! It's therefore essential, that you measure the voltage after the dimmer to get correct measurement results. Measuring the voltage before the dimmer is just plain wrong, especially for power factor calculation. The reason is, that the power factor calculation only can work in this idealized way, if you have a continuos flow of voltage and current in your system. Because then, if you have a phase shift between voltage and current, for example because of a capacitive load, you can masure that angle and calculate your power factor. With your leading edge dimmer, for example at 70% brightness setting, you have 30% of the sinewave no current flowing (switch is off) and the last 70% of the sine wave, the switch (dimmer) is on. If you now measure your voltage and current before the dimmer, your measurement device sees the continuos voltage with an angle of 0 degrees (no phase shift) but since the current flow is starting 30% later of the sine wave (means phase angle is 54 degress, but after that in phase with the voltage because it is a resistive load!) I assume, that your measurment device looks for the rise point in current and assumes this as the phase angle between voltage and current, resulting in the wrong reading for power factor as well as wattage. Connecting the voltage after the dimmer to your measurement device will lead to a state where the measurement device sees that the voltage is not switched on all the time and therefore sees that no phase angle between voltage and current exists. Of course this will only work if the measurement device is True RMS capable, because the dimmer output is no complete sine wave. Try it out, you will see that you get correct results when connecting it the right way ;)
You are right. I did the measurements to confirm your findings. The current is the same, but the voltage is different and therefore also the power factor. The question is now: What does the energy provider see? Does he see a reactive power or not, even without phase shift as the RMS calculation suggests. It seems that the bad power factor is made by the distortion of the wave (www.ti.com/lit/ds/symlink/lm3450.pdf , p: 11 ) not by a phase shift. So I learned something :-) Thank you for insisting.
Mr. Spiess: Beautiful but... your Power Factor formula at 17:57 is wrong.
It is not P/Q but, instead, P/S.
Power Factor is the cos(theta) and the closer to 1, the better.
True! It would be very high if Q is zero!
Indeed, Mr. Spiess. As you know, we, the machines, must obey the Law Zero of Robotics/AI, "Thou shalt not divide by zero".
I must say yours is a great channel with great and very well done material, which by the way made me to be your subscriber.
Thank you for all the videos you've published so far. They've really helped me to upgrade several of my systems.
The "One hand rule" was the first thing we learned at school. Seeing it in this video, also as first point, show how well educated and well versed Mr Spiess is in Electricity and Electronics.
As I said: I am no specialist. And I am left-handed. So I seem to have a problem with your rule @StringerNews ;-)
@StringerNews1 I second that 👍
Was told to brush the back of your hand against metal cases - if it was energised your arm would retract away from the danger
If you grip an energised circuit you cant let go
I appreciated seeing that rather than a vague "this is dangerous, don't do it" statement that covers the video host's arse but would be ignored by a lot of viewers!
I was trained as an electronics tech by the military in the 70's, and was taught the one-hand rule too. We were also taught to not wear watches or rings or dogtags for fear of them shorting stuff out. This was on aircraft which used 110VAC 400Hz power.
from what i remember from my tuitions, power factor can be corrected by using capacitors of the right size on the mains wires.
However there's another neat trick : if the mains are 3-phased, and the power factor is similar between all 3 live wires, the power factor can be corrected using a synchronous AC motor (yes, synchronous, not asynchronous) that runs without load. It'll probably heat up, but the motor ends up consuming the bad power factor just as capacitors would.
You are right. As I said I am no specialist. But sure, you can (and have to) correct the power factor in large installations.
It is called a synchronous condenser. On a synchronous AC motor you can vary the amout of reactive power consumed or produced by changing the DC voltaged applied to the rotor.
@@matthewmaxwell-burton4549 Ah, good to know. cheers!
As an electrician mainly working in commercial settings (3 phase here) I am extremely jealous of your 3 phase residential power! Sometimes the single phase (one 220v phase split to 2 110v legs) we have for residential power is very annoying! Very interesting video, btw. Thanks for all you do for us out here in TH-cam land!
You are welcome! Here, distances are short. Maybe this is the reason we use this method.
best content to see before bed time in NA, thank you Andreas! Very informative, simple and Swiss accenty. Happy to be in the front row.
* Swiss accent intensifies *
Glad you enjoyed it! So you are a "night owl" ;-)
I'm gonna need to watch this video again and again to apprehend the concepts, but its clearly explained as always. Thanks Andreas!
Glad it was helpful!
Thank you very much for making such videos, which helps not someone who learning electricty from 0, but jump-starters and diy-ers who started w/o advanced/deep-basic knowledge in electricity!
You are welcome.This channel is made for ambitious people ;-)
Hi Andreas.
Excellent and accurate explanation.
In Italy only those who request a three-phase contract receive all three phases: the energy meters are simpler and less expensive (from corridor whispers they should cost less than 40 euros each to the energy distributor, considering that in Italy only for E-distribution we talk about 33 million meters, three-phase and single-phase together ... with a hundredth of difference each we make a good figure.
I have seen that in Germany, the only country where I have been able to see a home meter, instead they carry three-phase electricity also in homes, I don't know in the rest of Europe.
Here in Italy, at least years ago, before the liberalization of the market, (Enel was a non-profit national body, but in fact it was a monopoly) the customer who wanted a three-phase contract in a civil home had to sign an indemnity on the dangerousness of the voltage at 400V.
In all cases, the distribution lines are all three-phase at 400V, with the same cross-section of cables it transports twice the power compared to a single-phase system, but the derivations for the individual supplies (we could improperly call it the last mile) are all single-phase to exception of those who specifically request a three-phase supply
Thank you for the update. Here in Switzerland we also have three phases to all homes.
@@AndreasSpiess In the UK we have a single phase to most homes. We can request three, but at a cost. Factories etc. have three phases.
Thank-you Herr Eng. Spiess for all of your great videos. Your information is always accurate and very professionally presented. In North America, houses do indeed have a 120/240 V split phase system that work well. Large apartment buildings often have three phase systems with 120/208 V, using the phase voltage to create 208V rather than 240V. This is annoying as kitchen ranges and clothes dryers meant to work on 240V are now operating at 208, which delivers only 75% of the expected power.
Thank you for the additional information!
Does that mean you in America can use European appliances that need 220-240V by connecting them not to Live and Neutral wires but to Live1 and Live2?
Oops, I missed that you in America have 60 Hz, but we in Europe have 50 Hz. So attention is needed regarding freq range the device can work on.
You missed one important detail. 208V, 3 phase, 4 wire power (3 phases plus Neutral, what you call 120/208) is used here in Canada and the USA in apartment building and factories because you can run 3 phase motors for booster pumps, HVAC units, and industrial equipment AND 120V outlets (from any phase to neutral) from the same transformer and breaker panel. Industrial motors here are usually rated for 220V because 208 and 240 both fall within the +/- 10% voltage tolerance. So, while it is inconvenient for your 240V appliances it holds major cost and complexity savings for the electrical systems of the building.
If only I'd seen your video 18 months ago. Caught out by measuring voltage and current across different phases. Data looked correct but power consumption was too low compared to the bill. Turns out the electrician that did the install of 3P meter had an off by 1 error with the voltage feed on the 3P bus bar. Took me a while to figure that one out. This was using Schneider Electric measuring gear. Quite accurate but expensive. Great work as always.
Glad to read that my theory worked ;-)
I assume this not only happened to you. This was one reason for that video.
When looking at RMS to DC converters, it good to look at how well they respond to the signal "Crest Factor" which is an indicator of how close the signal being measured is to a sine wave. e.g. Crest factor is a parameter of a waveform showing the ratio of peak values to the effective value.
Thank you for the addition. If I remember right, GreatScott did once a test with such converters. So far I never worked with such converters.
In the UK we normally ONLY are supplied with a SINGLE phase supply. The three phases of a local final transformer are shared as equally as possible between multiple houses. e.g. the first pair or first two pairs of houses will be fed from one phase, then the next group of houses, then the third group from the other two phases Some households MAY receive a three phase supply if it has been requested (and approved) from the distribution company. This may or may not be the same company who bills the premises (more commonly not). If a business is being run from home premises that requires three phase, quite often, depending on the area, the local council will be told and business rates applied to the premises! That is AFTER they may take you to court for unlawfully setting up a business without gaining planning approval first!!
Smart meters in future will almost certainly start charging (and more costly charges!) for reactive power since it causes current loading problems for the localised grid area - the reactive (but REAL) current can exceed the local capacity of the grid cables, hence requiring more expensive infrastructure. This is "partly" due to the massive increase in non PFC compensated switch mode power supplies in homes driving SELV (low voltage) LEDS. It is also complicated by the increase in solar PV usage WITHOUT the relevant storage of the excess which instead goes straight back to the local grid.
We will see what happens. Here often the energy is not much more expensive than a fixed price for the network. And I assume pricing will change if people more and more start to produce their own (peak) energy...
In addition to better measurement, another advantage of the Sonoff Pow R2 over the older version is improved fire safety of the design.
Good to know. Thanks!
There are 2 reasons to measure AC mains.
1) Because there is a need to know how much power is being used.
2) To know *IF* power is being used.
This video had great information for case 1. But, what about case 2 ?
True, if the answer is available for case 1, then case 2 is known. But, case 1 is often more complicated and more expensive. What about a simple cheap solution to case 2.
But, you may ask, why be interested in only case 2?
For example, a microcontroller can be used to mimic the IR input to a lot of IR controlled devices, like Air Conditioners, TVs, and a lot of others.
Unfortunately such a device does not give good feedback to the microcontroller, so the microcontroller can't know if sending the "cycle power" command worked and actually turned the device ON or OFF.
One way the microcontroller can know if the device is turned ON or OFF is *if* the device is using power. Exactly how much power is of much less concern, maybe only that the ON state is a lot more than the OFF (or standby) state.
Here is a simple solution that i used which is protected from mains:
In a video #321, "the guy with the Swiss accent" mentioned some current sensors usually built off of the Allegro ACS712 hall sensor (or something similar), which he rightly discouraged for use with mains - at least as-is. Only with luck will that chip work with mains. And relying on luck when working with mains is a quick way to posthumously earn a Darwin Award. Since that chip is only rated for a working voltage of 100v - sending 120v of mains AC through it might work, but it's not a good idea; And if your mains are 240V... that's almost 700v peak-to-peak and not to even be thought of.
However, that little chip (or any similar chip) can be coerced into working with mains very safely - although it comes with a loss of accuracy. Again, if the real question is *IF* power is flowing, then accuracy is not very important.
Here is what i did:
I took a large eye-hook screw (4cm or 1.5inch diameter) that a magnet would stick to (stainless steel is not good) and sawed of the screw part, this left an iron loop with a small gap where the loop comes together. Then i wrapped some heavy gauge insulated power wire around the metal of this loop. Starting from near the gap i wrapped a spiral around the metal until it got to the other side of that small gap - i got 25 tight turns. Then i used hot glue to place one of those the hall-effect sensor chips into the center area of the gap... you want the gap just big enough to fit the chip without damaging it.
Power from one line of the mains goes through the heavy duty wire in the loop. If the wire used is designed for use with mains power then this is as safe as any extension cord since the mains power is completely isolated (as long as the insulation does not melt). And now the microcontroller can read the hall sensor to see if there is current - and if is current flowing then power is being used.
The reading is not exactly accurate - as particularly at very low current flow there is a fair amount of noise. But since the difference between stand-by and someone actually using the microwave oven is really huge, my microcontroller can easily tell if the microwave was turned on.
On the software side, the program must be aware that this signal is AC and switches from positive to negative flow 50-60 times per second. I have mine probe as fast as possible for 200ms and average the absolute value of the results. But that is a whole other discussion.
Thank you for sharing your design. It is an interesting concpt!
never heard that advice about the hand on the pocket. great way to not forget !
Simple rules are a good thing ;-)
In the US we do have 3 phases but that is typically industrial although a residence can have it if it is available at the local distribution point, is needed and requested. Residential customer might have to pay for that in fracture to be installed up to a point and the voltage on each phase is 208 with respect to earth/neutral/common. The two phases you talk about is simply single phase coming down the local transmission lines [2 wires/14KV] to a transformer that puts out 240V with a center tap that is used as neutral to reference 120V off of each line. This way it is single phase 240V and when referenced to neutral 120V using only half of the phase but still 60Hz.
Thank you for your explanation. I think I showed the "split phase" concept in the video. I named the two wires "phases" because it has a shift of 180 degrees if measured against neural which can be relevant for measuring power (if I understood right)
I built one of these home energy monitors for my split phase system using two CT clamps, an AC/AC transformer, an Arduino Uno, and Robert Wall's EmonlibCM. The latter is essential for this project because he takes all the complex calculations from an electrical engineering PHd background and does them for you, to the precise timing known on the Uno's chipset.
It's also surprisingly dangerous - even though the CT clamps aren't actually touching the mains wire, if they do not have a load resistor or a TVS diode, they will explode in a big puff of smoke if you clamp them around a wire carrying 100 amps+ of current. Because with no load resistor, they will generate theoretically millions of volts. As i nearly discovered.
Your clamps are simple transformers with one primary and many secundary turns. So indeed, they are made to create high voltages...
The Kill a Watt type meters are convenient and have become reasonably inexpensive.Two uses I find they're handy for are for checking the output of my old school generator, and for establishing an idea of how much power small appliances use.
I agree.
Nice video, and a complicated topic. One thing not covered here though, don't always expect the Current waveform to be sinusoidal. Switch mode power supplies, CFL bulbs, LED lamps are all non-sinusoidal and measuring power factor, and true power is very difficult. These modules make this possible because they have delta-sigma converters and an 'algorhythm' to determine the true power. You can use the LTC1966 AC to true RMS converter to do the RMS calculation for Voltage and Current. Then regardless of the wave shape the power factor can be calculated (V_avg * I_avg) / (V_rms * I_rms). Have a look at those modules, they work really well with Arduino.
You are right. I think I showed also some other chips which do these RMS calculations. Fortunately they are no more rare...
I am a retired Electrical Engineer and I found this extremely interesting and there are a few places where I need to watch again because you said something which surprised me. Power Factor correction is extremely important in industry and the supplier will shout at you very loudly (as well as charging you) if it drops low. The domestic user pays for power factor indirectly because VAR does not do any work but you pay for it. During my Apprenticeship Elec Tech called this Wattless Power. I need to look at your Oscillospcope traces again mainly. At 75 yrs old I do not need to, just curious.
Thank you.
What is VAR
@@solidfuel0 VAR = Volt Amperes Reactive
@James Goacher If by domestic user you mean residential - as opposed to commercial/industrial - then they may not be paying for reactive power. The Ferraris type meter and its electronic equivalent used in North America tally only real power.
@@kiowablue2862 I have never done domestic electricity apart from the necessary repairs of appliances. The last Electricity Meter I saw was the Eddy Current disc type. My present meter is in a cupbord outside and is a block of something with a couple of digital displays which I read remotely cos it supposed to be a Smart Meter, never understood that term. I am way out of date with equipment now because I have been retired for fifteen years from a fast moving field. I keep up to some extent but I do not need to design anything because I have no problems to solve (mostly). I am watching this TH-cam channel because of Mr Spiesss' (that is grammatically correct s appostrophe not apostrophe s) other output because I am inventing problems to solve with Arduino type things.
@James: To be still curious at 75 is a very good thing. Without that you probably would get old fast. I am 12 years younger but already see colleagues which stopped to be curious...
I have a SonOff V2 and it measured for over a year on the same walll plug the more reliable energymaster was used for.
After 1 year and 500 kWh consumption the difference is below 0,4% or less than 2 kWh.
Did not change anything. Since then I purchased a different model that is housed in a plug in plug design switch for 16 A max.
Results are 0,5% different so not that bad to get behind consumption of a dryer over a year to see that seasonal curve if that exists or that of a washing machine or even a night light outside and its movement sensor. It is a 32 Watt fluter and used 1 kWh per month so just 12 kWh a year.
Who knows what a light does during the deep night so we measured to be sure that this is not a silent or hidden energy burner.
If you check each single pluged in device and also the directly grid connected pieces like window jalousies you get a good feeling about your home energy consumption and efficiency especially if you make an inventory list of all devices and its standby watt and usage and an estimated use time per day ...
If you then enjoy your holiday you get behind if your standby estimation and device inventory is right or not.
That makes things easier to change habits or devices ... for example a smaller oven to heat up for just a fresh bread or piece of pizza instead of the usual oven which takes kWh to heat it up before starting to cook.
When do you turn of a water cooker ... if it is already cooking or earlier and what is the difference?
So we measured the water cattle for a quarter and guess what: it is used far often or with more water than assumed. It uses 5% of household energy consumption ... for tea mostly.
Very interesting info. So it seems that these chips are quite precise.
An excellent review of the topic. I had forgotten allot of this. Power factors, RMS and needed a refresher. Very educational and you are a great teacher. Thank you.
Excellent job covering the top. I very much appreciate it!
Glad it was helpful!
I monkey around with various "cheapo" AC power meters and capture devices (like the PZEM-004), but in the end I decided to get "real" and purchased a Fluke 377FC RMS clamp meter (with stand-alone logging!). It's very helpful to have an accurate sanity-check to make sure that your hacked-in stuff is returning data that is meaningful. Also note that a lot of cheaper clamp meters cannot measure inductive or switched loads correctly (non-RMS).
Good idea to have a sound meter for reference (if you can afford it...)
Three phase power is used in the United States in places like almost all of New York City.
The Two phase system allows for larger appliances to run on 240v compared to most other household appliances which run on 120v.
This way most normal homes have 120v wiring with occasional outlets at 240v for high powered AC units, clothes dryers, and ovens.
With a standard wall socket voltage of 120v, the three phase wiring would only provide 208v and not 240v.
This is actually convenient in places like NY City where they don't want the consumer to be running high powered devices like electric ovens or electric clothes dryers which are, as far as the electrical grid is concerned, better powered by gas.
Thank you for the additional information!
The other thing to note for left-handers: It's very difficult, but try to keep your left hand in your pocket rather than your right. Current will always flow through the easiest path to ground and that means (unless your heart is on the right - a VERY small minority are) then slightly more current will flow THROUGH your heart to ground from your arm down your left side. Current will still flow down your right side too but your heart is not in the way. If you receive a shock through your right arm, current will still flow through your heart, but mainly NOT and in any case will be much smaller, hence marginally safer.I learnt this over 50 years ago from an OLD TV engineer who used to have to work with 10kV to 35kV or more in CRT TVs. The bigger the screen, the higher the voltage (usually) and colour screens more than mono.
Here all honest people have the.heart at the „right“ side. So fortunately not too uncommon;-) But you are right, of course.
@@AndreasSpiess :)) LOL
It's a pleasure to sit in the first row :)
Thank you!
Indeed ! We're over 241K at this moment. Rather crowded here on the first row. But where else would you like to be then ?
@@PhG1961 By first row, I meant early access as a Patreon :)
13:16 - Also as I recall if the voltage across both wires is not 0, you have a leak somewhere if you haven't noticed yet (usually it's sparkly and hot)
You are right. In this case our fuse would trip immediately. Because it monitors leak currents.
Thanks for the explanation of the meter at the very end. I have one of these and wondered about the watts reading when the power factor was low. I have a solar system and inverter so the power coming out of my inverter is not accurate just from the watts reading unless power factor is 1. When you explained that it should be labeled VA that makes more sense to me.
Both are needed. On motors you sometimes find both numbers.
Hi Mr.andreas you show device at 9:10 . I want to detect AC mains (healthy voltage) does it do the job? I am building a device which can see whether mains voltage is ok or not. It is ok if voltage above 200v ac if it is below 200v it is not healthy phase. What do you recommend to use in this scenario?
If you want to have a signal for a precise voltage you have to use something like the ZMPT101B. The "mains checker" has no precise threshold. Maybe you can experiment with different resistors if you get it precise enough for your needs.
Thanks i will try some resistor divider. I hope it will works..
Hi andreas any everybody, 12:37 can you suggest how can i measure current with bare zmct103c. Any article or links please..
I would search for "zmct103c Arduino".
@@AndreasSpiess i did it but i cant find satisfied results.
@9:20 What should be the distance between AC and DC? Arent optocouplers made to withstand 2kV'ish+ volatages? Or the typical pcb not suitable for such clearance?
I am not a specialist. But often they create a slot in the PCB to separate 240V from DC
@@AndreasSpiess Thanks for the reply. I guess a slot can never hurt and is overall a good practice. But if it was only about the distance then manufacturers would've surely used a bigger case for the optocoupler I guess.
Great video as usuaI. I also share your concern about connecting to mains. It's great that we now have smart plugs with built in monitoring but I wonder about the accuracy. For constant loads directly connected to the panel, it might be easiest to read the nameplate or use a Current probe with your multimeter. Then monitor when the load is switched on. For variable loads (like my heat pump) I thought about the AD8210 Current sense amplifier and a current transformer and burden resistor. Current transformers are evidently an accepted practice. My solar panel installer put one in my panel.
I recently made a video about commercially available power meters...
That old metex brings back memories or my early days working as a measure and control technician back in the late 80s
It is not as old ;-) I bought it because it acts as a pretty accurate AC power meter.
@@AndreasSpiessthey didn’t change the design much over the years😅
Can we masure house consuption end send the values via mqtt to Raspbery with Shelly device(using modify firmware)? Or with an Esp 8266 + CT? A new video in this direction will be very halpfull. Thank you for all your work!
I plan to install the shelly3EM in my fuse box to do exactly that. It should have native MQTT support.
Look up open energy monitor. I built by own system using their ideas on an arduino nano connecting to a pi.
Good Job ! it's a real pleasure to watch you !
Please continue , .. Success !
Thank you, I will!
Hello Andreas,
thank you for another brilliant video and all the work you do on this channel - to start with.
Concerning the measuring device shown at 23:22 - I absolutely do not understand the wiring diagram on the website. Could you please explain where to connect L, N and the leads to the load to these four connectors on the device? Must be a mental hickup...
Thank you!
#2 is not used. #1 is neutral IN, #3 is neutral out, and #4 is Line IN and OUT,
UK homes only have single phase as standard. Neighbours either side will have the other two phases.
Thanks for the information. Maybe a compromise between the US and Europe...
@@AndreasSpiess UK has 100Amp main fuse so probably just different ways to share the power out. US definitely needs more than one phase for running cookers and heating, 120V would need a lot of copper for the current.
UK is Europe, just not mainland ;)
So two neighbours can conspire to connect their phases across the garden and milk 400V ?
@@matteopascoli It's being metered in each house. Anyone can get the phase installed in their house if they want but unless your running heavy machinery it's not really required.
@@Sal--- Wrong, Brexit took the UK out of the EU. The UK remains as firmly on the European continent as Switzerland does.
Both AC/DC voltages and Currents can be measured safely (isolated) using chips like ACPL7900 or equivalent. They produce a differential voltage in proportion to input voltage or current.
True. I omitted them because of time. The video is already quite long...
The yellow Metrrixx multimeter has the state of an old Nokia cellphone. Always reliable, tough and still working after dropping from the ladder. Only changing the mA fuse from time to time and a battery every year (if you did not forget to switch it off) 😉
True. Mine is already very old :-)
14:45 About CT by clamp to Neutral wire, but if your wire (line) of my house is Live (Hot) 1/Live (Hot) 2 wire from DU (220V 50/60Hz). How can i use this CT?
I do not know the situation in your country. So you have to ask an electrician.
Power factor is a big problem for those current transformer devices that are sold to be clamped around the main tails to/from your electric meter in order to report the consumption of the whole house, even when the installation only has one phase delivered to it, as is the case for almost all UK houses¹.
The ones I've used don't measure the mains voltage - *at all*, let alone in tandem with the current - and yet they report power rather than current, so presumably they're just assuming a mains voltage of 240V RMS and an arbitrary power factor?!
I've used three such devices - the Energenie Mi|Home MIHO006, the Loop electricity monitor, and the Owl CM160 - and they all reported power consumption figures that were *significantly* wrong: in the region of 30% out! They each reported different figures, too, so it seems they're using different assumed values.
If the difference was only 5% or even 10% I wouldn't care nearly as much, but 30% is unacceptable, IMO.
The mains voltage here (as measured by a couple of TP-Link HS110 devices and imported to InfluxDB+Grafana) has ranged from 230V to 245V over the past month, so even assuming that to be constant introduces some amount of error...
These days I'm using an ESP32 and a phototransistor to measure the duration between the flashes of the red LED ("1000 imp/kWh") on my electricity meter, very similar to the system described here: esphome.io/cookbook/power_meter.html (though I'm using ESPHome's "pulse width" sensor, because ESPHome's specific pulse counter implementation means that the more frequently you want it to report a value, the less accurate its readings get, to the point that, with a report every ~10 seconds, I had a *resolution* of around 400W!)
This method is very accurate - it matches what's displayed by my utility-provided smart meter's in-home display - and since it uses the meter's own measurement hardware, it doesn't have to worry about the power factor - it would even automatically switch to reporting VA if my supplier decided to start charging me for apparent power, as Big Clive suggests they will! ;)
¹ Which will itself become more of a problem in the coming years: 60-100A at 240V [14-24kW] has been plenty for most households so far, even with a 8-12kW electric shower, but having e.g. an electric shower *and* an EV charger can create problems - both practical and regulatory - and 3-phase makes faster EV charging more practical as well (not that it's needed for most people)... But I don't think even houses being built in 2020 have 3-phase supplies, sadly...
² Energenie: energenie4u.co.uk/catalogue/product/MIHO006 | Loop: www.amazon.co.uk/dp/B00YNCJB3S | Owl: www.amazon.co.uk/dp/B004BDNR84
I do not know the power meters you used. But it could be that they cannot measure "true" RMS. It would also be interesting if it is only a calibration issue or a random error.
the chips graphic was Hilarious! well done
Thank you!
Thank you for putting the links in the description.
You are welcome!
Thank you very much for the very informative video.
What is the Type of the Battery powered oscilloscope, and where can it be bought?
Can you also access the data from the power monitor with the display (called P06S apparently)? I didn't find any information about a serial interface like the PZEM-004T has. Would be nice to have a display and broadcast the data.
This seems similar: hackaday.com/2016/07/11/put-a-reverse-engineered-power-meter-in-your-toolkit/
So not that easy to do safely. Also, some versions are not STM32-based.
I do not like to work with mains. This is why I prefer wireless and ready-made devices...
This is something i was looking for. But how can i send that 21:21 data to a server to monitor the readings online
I do not thing this device offers a machine readable interface. So you have to chose a different one.
@@AndreasSpiess do you have any suggestions of such a device / board
Great video, thanks. I would like to ask about the model of battery powerrd oscilloscope and where Can I buy he same?
It's an older model of this one I think: www.banggood.com/MINI-DS213-Digital-Storage-Oscilloscope-Portable-15MHz-Bandwidth-100MSa-or-s-Sampling-Rate-2-Analog-Channels+2-Digital-Channels-3-Inch-Screen-With-Logic-Trigger-p-1412378.html?rmmds=myorder&cur_warehouse=CZ
I loved the video and how it is presented. Very practical and of great didactic contribution, a pity not to have seen it until this 2022! I just found your channel, you already have one more subscriber.😉
Welcome aboard the channel!
Hello, thanku very much for the informations, very helpfull, i would like to ask how much is the phase angle error for current transformer?
I do not know.
This video was extremely useful!! I am in the process of making a datalogger with Arduino and also exploring different methods to connect to mains and DC powered devices. Thanks.
Glad it was helpful!
Andreas, when will the second row seats start to get occupied?
60% of the views come from the second row (non-subscribers)...
@@AndreasSpiess I was thinking more in the direction of when will the first row overflow, but the information you provided really surprised me
Great videos! This one and 321... Working on a project that will turn on and off a load of less than 5amps at 110v... Want to include power monitoring and I am using acs 712 for now... For this application what would be the advantage of a more complex solution as the ones you presented here?
You need to measure very fast to get the sine wave correctly. The specialized chips do that for you.
Excellent, as always. Thank you for an instructive and entertaining video. Much appreciated.
Glad you enjoyed it!
Excellent explanations.
Glad you liked it
Here's an interesting question...
How would you go about monitoring actual high voltages? ...ie electric fence voltages (~10kV, ~150mA, 1Hz ...but with short duration soliton pulse)
I made a few Lora fence monitors and am using basic voltage dividers. Looking for a more robust solution measuring voltage using opto isolators though.
neon lamp and LDR?
I do not know. Maybe with a parallel wire and a resistor? You should get some energy "transmitted". Or a simple radio receiver with an antenna. There you should easily hear the sound of the voltage spike.
I would not connect resistors to the wire itself because it can reduce the maximum voltage considerably.
Get an inductive pick-up off an old automotive timing light. The pickup clamps around the spark plug wire and fires the strobe. A simple interface to the pick-up will detect the short duration high voltage pulse.
Great video as always 👍
Thanks for sharing 👍😀
You are welcome!
5:00 was the scope saturating at the peaks or was there another component/source issue?
Hopefully not from the scope if you look at its price tag ;-) I assume it comes from the open transformer but did not do any investigations.
Could you please assist in testing current of PCB tracks. I have a problem where I have a short on a pcb and need to track it down. I have been told there is a probe that will show the magnetic fields on pcb.
PCB tracks usually are tested with an ohm meter.
In Germany many old electricity counter are now beeing replaced by digital ones which offer an I/R interface to transmit the data. Also common gas meters offer the possibility to read the data via a reed contact. I've seen several videos on how to monitor gas and electricity by that means, but none of them reach your quality. Just a nudge...
You are right. I also saw some videos with the ESPcam. In our house we have a central distribution and the counters are not in every home. So I have no way to test it.
But I installed an Shelly 3M and I am very happy with it. Like that I immediately see which phase (and which device) uses the most energy.
Sir for measure voltage and current on single phase transformers for test automation! Could you please provide me some hints thank you
Inputs and outputs of transformers have to be measured like all other AC systems.
@Andreas Spiess I want my esp8266 to log power consumption of my air conditioner. Which module to use ? I am clueless. Please Help.
I share my knowledge in my videos and unfortunately do not have time for individual research :-(
@@AndreasSpiess please don't misinterpret. To your knowledge, is there any AC energy meter that can be programmed with arduino IDE?
Did you watch the video till the end? There I showed them.
Grest work, as always👍
Thank you! 👍
Good stuff! Any recommendations on AC current meters which output a DC proportional voltage? This would allow the ucon to do other stuff and just read at any time.
I do not know how to do the RMS calculations with analog means. But I did not search for long.
Do you, by chance, know if the Shelly EM can be "tasmotized"? Once again, thank you for sharing your knowledge
github.com/arendst/Tasmota/issues/8055
How interesting to see the PF of that dimmer
I also was surprised. But I checked other sources and it seems to be "real".
Major reason for AC in power comes from transmission in the old days. AC can be transformed to hundred of kilo volts to reduce current and hence transmission loss. Not possible in the old days with DC. In modern time it is very different. If we needed to design this today we would select all DC. With modern hight power switching electronic DC can be transformed up and down in voltage more efficent than AC. Som of the large power distribution companies are planing to provide DC power to private households. It is a very long plan is it is not easy to change now. But the saving will be large in reduced power loss. In an transition periode we will get both AC and DC. Already several decades ago power transmission was often DC to reduce the loss that comes with AC due to induction issues generation surface effects in the cables.
Thanks for your info. We have ABB here who are quite involved in the highest voltage transmission ( or was. I do not have the actual situation what still belongs to them).
Here we also discuss DC underground cables because it is nearly impossible to build new traditional lines anymore. And DC fits well with solar power.
the assumption is that the AC is a true sine wave which, as you pointed out, may be far from true.
Using a uC one ought to be able to calculate the actual area below the curve (by slicing) using Riemann Sums or the Trapezoidal Rule
I do not know how they do their RMS calculations, but I assume these chips or the Arduino library I used use one of the concepts mentioned by you.
The dimmer showed that you are right with the sine...
Would love to see some testing of how accurate (or not) the Sonoff devices actually are.
If I remember right I did some testing in the old video. But this is not my specialty :-(
I'm getting good values with the Sonoff Pow R2 (after calibration), while the older Sonoff Pow should be less accurate.
Learnt two new tricks. thanks!
How can I measure 20kHz 70% dutyCycle pulsed DC current?
I assume with a small resistor and an oscilloscope. Maybe you can replace a resistor with a hall sensor shown in this video. But you have to check their max. frequency.
Great video, but I still don't understand how AC power usage can be measured, if there's a constant volt going backward and forward won't that voltage be constantly be replenished and if so how can what is used be measured if it's constantly replaced. Baffled. Thankyou for the information though. Stefan
You can use rectifiers, for example. Then you only get positive voltage.
I always look forward to your videos. so professional and informative!
do you have a recommendation to measure mains power before the mains breaker? There are occasions when city power is down and i open the mains breaker to back-feed a generator power to the mains panel. i would like to monitor when city power is restored. My intention is to find a suitable sensor to monitor one or both 240 mains cable in the power panel. I understand the a cable clamp is used to measure current, however, since the mains breaker is open and voltage is present from city power, no (home) load is connected so i assume zero current.
can a current clamp be used to sense when the city power is restored? I would like to measure any voltage activity on city power and have an Arduino trigger a relay to provide an audio indication, then silence the alert.
what contactless/clamp sensor would you recommend?
I release you of ALL liability when answering (thought i would add this for your protection).
Keep up the OUTSTANDING work, Sir!
I have no knowledge in wiring such distribution box. You have to ask somebody who knows much more. You can use the clamps whenever you have current flowing through a wire.
Ironically most modern power supplies are switch mode and have to convert the incoming AC to DC first , DC transmission is more efficient but the technology to convert between voltages at DC wasn't available back in the Edisson/Tesla years so AC was the better choice but now DC would be better.
You are right. And today DC has a comeback for power distribution (e.g. underground cables). Silikon is cheap...
I want to put a power monitor for the apartment in my fuse box and publish via mqtt. The FI seems to be only 25A. What's the best choice for accuracy+speed (want to try to detect different devices by their power profile like sense.com)? I have a PZEM-004T with a 100A CT but haven't put it in yet. How much more accurate would a 30CT coil be? Are the CT versions just safer or also less precise? What about a Sonoff Pow R2? It seems to be only 20A, but I guess that'd be enough. What happens if it went over 20A? Many questions :)
If you want to have a more accurate measurement with your PZEM-004T 100CT, and your max current is less than 50A (in most of the cases true for residential houses), then you can make 2 rounds with your source cable in the CT coil.
I you do this, then you will use the PZEM in full scale (0-100A) but then you need to divide the result again by 2 off course to get the correct value.
@@svdhallen Thanks. That would be easiest, but the wire is too thick and also too short (and hard to access - since I'm renting I don't want to rip the box out of the wall).
The PZEM-004T claims 0.5% accuracy - does that mean 0.125% accuracy for a 25A CT? I'm confused by the use of percentage instead of some constant like for the resolution.
How could I measure real time power on a 3 phase system. I saw I could use a 6 channel ESP energy meter. Because I wanna do it with ESPHome and homeassistant. But I dont find that board here in germany (Shipping is very expensive ) What would you recommend me ? Thank you !
I use the Shelly 3M for that purpose because I do not want to build a mains device myself. It is not cheap, but it works.
I have 7 24v thermal actuator heads. If I had 24v transformer at 1amp, would that be sufficient to power 7 thermal actuators at once, or any combination of the 1-7 powered?
Low energy input approx. 3W - 3.5W.
• Breakaway current: 0.35A (24V)
• 24V can be supplied from either an AC or DC source.
• Coil resistance: 24V: 115 Ohms +/-29
Max power consumption looks like: 7*3.5W = 24.5W.
Your transformer is 24W (24 volt * 1 Ampere).
So you are a fraction below, but I would give it a try, or to be safe go one step up in transformer power.
You have to do your calculations. 24 volts is ok. But you also have to take into account the max. current all actuators will draw. Of course the transformer must be capable of sourcing also this current. 1 A is sufficient for max. 3 actuators (3x350mA).
@@AndreasSpiess Thank you! Yes I was confused by the documentation for their official wiring centre. It said that "With its 50 VA transformer, the 24V version allows up to 16 x
3W electrothermic heads to be controlled" which is 2 amperes, so with only half I calculated at 1 ampere for own setup. It does say later in the docs that their is 4A, transformer protection. Ref EWC-1: emmeti.co.uk/wp-content/uploads/EWC-Wiring-boxes-technical-Product-guide-April-2016-V2.pdf
13:12 IF we use two wires then we can get different current (current of leakage), as I think. Zero-result mean no leakage
I'd like to know if there is a device that will tell me if I am feeding power to the grid or drawing power from the grid. This is to use excess solar power in water heating and battery charging. Is there a device that will tell me this? (Or do I have to build something to detect phase of current/voltage and then work it out from that assuming I don't have a motor running that will skew those results)
@Benny Indeed there is. Robin at mk2pvrouter.co.uk sells a kit that does exactly what you're asking about.
@@kiowablue2862 Thanks Bill. Excellent.
Is there any dc voltage and current measurement video for 16cell 100amp lifep04 cells. Want to make bms with esp32 is it possible.
I never covered high power applications on this channel.
@@AndreasSpiess ok can you do something similar with smaller 13s 48v. Hope thats fine its under 60v dc
great teacher as always
Thank you! 😃
*boom* - that was the sound of my brain after getting to the end of your video
Is this good or bad?
Hi Andreas
Is it possible to use PZEM044T for three phase(ac) power measuring hooked with an arduino?
Am Working on a diy project for measuring 3phase current & voltage for a 240AC motor.
Any other better ideas too is a welcome.
I use a Shelly 3M. It should be possible to do it with single Phase systems. But the voltage sensors have to be at the same phase as the current sensors
thanks@@AndreasSpiess , let me try it.
Sir, am making homeautomation project based on ESP32 and relay module, project is properly worked. But i don't understand which protocol used.
As per my knowledge
HTTP protocol for WiFi networking.
Am i right sir ?
And second question is relay module connect to ESP32 through 10 wire so what is the protocol for this type communication ?
1. You can use different protocols over WiFi. I use MQTT. I would Google "Tasmota."
2. Each relay is usually controlled by an ESP32 pin (and a transistor). No protocol is needed other than on-off.
@@AndreasSpiess thankyou sir
Thanks sir, very informative and useful for my projects, and the information delivery is very good. Subbed!
Welcome aboard the channel!
any option for measuring up to 200a current? can i use different transformer on pzem004t?
I think so. The pzem004t does not care about the winding ratio, just the voltage.
have you ever used SCT-019 CT?
@@ahmadmuhaimin2852 no
Thank you. I get really crazy of al thos people saying volts, amperage or wattage..those people probably also say they ran 200distance..
What is then the correct word for volts?
Please make a video with ATM90E26 and esp32
You get already a ready made board (google "IPEM-1 ESP32UE ATM90E32 IoT Power Energy Monitor Board"). And an ESPhome integration.
@10:33 "Everybody can do sine waves." - I beg to differ. Transcendental waveforms are _the_ most difficult ones to generate. In the digital domain, at least. ;P
(Did some research on this matter in a previous life)
You are right. I meant "measuring sine waves", not creating them...
@@AndreasSpiess I know. I was just joking. Anyway, great video, as always!
Can you work on meausring energy by ade7758 with esp8266?
I did not find any Maker boards with the chip. AFAIK the Shelly's contain this chip.
Many people made board their own.
This is a really great video, thank you
Glad you liked it!
Excellent video.
Thank you very much!
please make a video about distortion power factor
I am not sure if this is a topic of general interest :-(
Hilarious - the arm thing. Good presentation. Especially for lay person...
Thank you!
good job. I learn a lot with you.
I have two questions.
In my house I have 2 different lines, one with solar off grid and another normal electrical grid 230v in Spain.
The problem comes when by mistake, or by failure in one of the relays of the electrical panel, some cable is attached from one line to the other. Then in the inverter the transistors explode.
Is there any way to protect the off grid inverter so that it stops the moment it detects a different line?
The second question is: I use relays SSR-40DA, to commute between solar line and normal line, when the voltage in the batteries is low or some sensor drives the change of line. ¿HOw i can protect the thyristor on way out?
If the thyristor is in short , what sensor i can use to drive it to stop the inversor.
I can send you photos is you want it.
Have a look at Victron solar chargers + inverters, not cheap, but do what you want and no more exploding transistors or SCR resulting in loss of power.
@@rolandleusden You are right, but victron is not affordable for my, although there is other brand cheaper than victron that I could use.
In general, I'm not very friend of all in one, because it normally are expensive device and complicated to repair, and when you have a failure and your are not able to fix it, you'll lost a lot of money, and loss of power.
However, if you use individual, well-kown and cheap modules, possibly you are able to fix it, and the repair costs will be very cheap and at least you can use some module independently.
It's true, that you don't have to complicate, if you use this kind of all in one.
Perhaps, it is the moment to change my mind and I must extend the installation.
Thanks.
@Carlos: I have not a lot of know-how in this area, so I am not a big help. High currents and high voltages are a very different area to where I usually work. This video is more or less what I know :-(
What is the main reason that a scope that runs off the mains is grounded?
I do not know and asked this question myself, too. Maybe somebody can „enlighten“ us?
An oscilloscope that isn't earth referenced must have all its channels isolated from each other (both signal and ground wires of the probes). Generally amplifiers, signal generators, power supplies, etc are all earth referenced. Any floating voltage connected to the ground wire of the probe will cause sparking and damage the equipment. Battery scopes do not face this problem, neither do power scopes as they use isolation transformers
I learned now about the other channels. This problem exists also with my battery powered oscilloscope and I was not aware. Maybe because I usually only use one channel with this one. Now I even pay more attention....
@@wp0049830 thank you for your answer, it has better helped me understand how to use my scope
Why didn't you include devices like SDM120? I think they are the right compromise between the pzem and a shelly EM
I did not know them :-(
@@AndreasSpiess time for another test then 😅
Probably too late... I will not cover this topic in the near future. The interest is not very big :-(
@@AndreasSpiess people in the home automation hobby do like to mess around with these things but they usually don't go the full DIY way, so pzem is the bare minimum with a wemos and you easily integrate energy monitoring in the home automation system.
thanks for this video and also for your wonderful youtube channel ❤️🌹
Glad you enjoy it!
Superb video!
Thank you very much!
Japan is also 2 phases, ~100V each. And half the country is 50Hz, the rest 60Hz.
Seems to be a quite complex system. Here only the railways use a different frequency (16 2/3) because early motors had more power during start with lower frequencies.
But why should there be a phase shift / reactive current when dimming a resistive load??
Good question. I do not know. Maybe somebody else?
@@AndreasSpiess Well, I found out. Your device doesn't correctly display the voltage. Your leading edge dimmer lowers the effective voltage by using only a part of the sine wave of the voltage. Your measuring device states 233V nonetheless of the dimming ratio. Did you maybe accidentally measure the input voltage (before the dimmer) instead of the output voltage (after the dimmer) with this device? A resistive load keeps a resistive load even when dimming and therefore power factor is always 1,0. Either you have accidentally connected/measured something wrong or the device is displaying wrong values.
If you watch other videos you see the same behavior. But your point is interesting: What happens if you connect the meter before or after the dimmer. The RMS power should be more or less the same... (The dimmer does not get hot).
According my knowledge, the power factor has to be measured before the dimmer because it is measured for a whole system.
@@AndreasSpiess Then these videos are totally wrong too! What you want to measure is, what your load (in this case your light bulb) receives not what your dimmer receives. The dimmer always receives the full sine wave of the voltage. Via fastly switching every half wave it then regulates the voltage your load receives. So your dimmer sees the full voltage, your load (light bulb) does not! It's therefore essential, that you measure the voltage after the dimmer to get correct measurement results.
Measuring the voltage before the dimmer is just plain wrong, especially for power factor calculation. The reason is, that the power factor calculation only can work in this idealized way, if you have a continuos flow of voltage and current in your system. Because then, if you have a phase shift between voltage and current, for example because of a capacitive load, you can masure that angle and calculate your power factor. With your leading edge dimmer, for example at 70% brightness setting, you have 30% of the sinewave no current flowing (switch is off) and the last 70% of the sine wave, the switch (dimmer) is on. If you now measure your voltage and current before the dimmer, your measurement device sees the continuos voltage with an angle of 0 degrees (no phase shift) but since the current flow is starting 30% later of the sine wave (means phase angle is 54 degress, but after that in phase with the voltage because it is a resistive load!) I assume, that your measurment device looks for the rise point in current and assumes this as the phase angle between voltage and current, resulting in the wrong reading for power factor as well as wattage.
Connecting the voltage after the dimmer to your measurement device will lead to a state where the measurement device sees that the voltage is not switched on all the time and therefore sees that no phase angle between voltage and current exists. Of course this will only work if the measurement device is True RMS capable, because the dimmer output is no complete sine wave.
Try it out, you will see that you get correct results when connecting it the right way ;)
You are right. I did the measurements to confirm your findings. The current is the same, but the voltage is different and therefore also the power factor. The question is now: What does the energy provider see? Does he see a reactive power or not, even without phase shift as the RMS calculation suggests.
It seems that the bad power factor is made by the distortion of the wave (www.ti.com/lit/ds/symlink/lm3450.pdf , p: 11 ) not by a phase shift. So I learned something :-) Thank you for insisting.