Improving the sensitivity of a Peacefair PZEM-022 power meter 

I think this will cause problems. You creating a magnetic short circuit which will cause trouble, probably not so much in wasted heat (if you use decent size wire) but the effect on the accuracy of the readings. That energy has to come from somewhere. My suggestion is to use a SPDT rocker switch that has a "(on) on" characteristic. The "(on)" standing for momentary action. In other words, you need to hold the switch for the x10 position and it will go back to the 1x when you let go. A quick search on RS components (UK) shows part no 197-7866 , a rocker switch rated for 16A that would do that (but other switches and distributors are available)

@t1d100: Thanks for noting these . They may help people troubleshooting their built.

Hi Andy, thanks for the comments. There is another video on my channel describing the original built of the meter showing the full spec and it has a parts list of all components in the description. Anyway I bought the box from RS-Components (aka RS-Online) stock no 1748901. You are quite right. It is of superb quality and not very expensive either. I believe RS has an Australia branch. If you use the stock number, the result on the (UK) RS website shows another box from the same series but the stock number refers correctly to the model GA8-20-6 by Takachi Electric. As for the other question, the PZEM-022 can't read lower than 20 mA (it just shows zero) but it will still calculate power for currents lower than 20mA. The whole point of this video was to improve it by adding a x10 switch so now it can read down to 2 mA. You could use the same mod with 20 instead of 10 windings and get it down to 1 mA, but now you would have to multiply the current and power values on the display by 20 instead of 10.

@@TheHWcave apologies for not getting back to you sooner mate. I have just switched on my RU-vid notification. 😂 Many thanks for the detailed explanation and tips. I can't wait to get myself a pzem022 and the box! Would you also have to know where to shop for a voltmeter or ammeter display module that can read starting from 0Vac and 1mA? My project is to assemble a self made QA testing device :) Thanks once again. I'm intrigued by your video and comment! :D

no worries, I don't know any voltmeter or ammeter modules that would do that without needing a separate power supply that keeps them going if the measured voltage is very low. Separate power opens a whole can of worms with respect of what is referenced to what and isolation between that supply and the measurement circuit... You may want to use batteries to be safe and separate circuits for volts and amps (don't share the battery between them). Another idea would be analog meters because they don't need external power but especially for the ammeter you need to watch out not to overload it. 1 mA resolution will be hard to find though. Most analog AC rated meters have a distorted scale because of physics, they are not very sensitive at the low end of the range. Last not least, analog or digital meter modules for AC will be averaging not true RMS. So the shown values will only be correct for a proper sine wave shape. If you plan to measure things that use other wave forms (rectangular or "modified sine" etc.) you need to factor in an error of probably 10% or more.

@@TheHWcave thanks for the prompt and informative reply again mate. That's exactly the problem Im facing now. Need to stick with digital LED/LCD meters as it is easier more accurate to read. Though as you described, most AC meters I can find reads only from 80V or 10mA the lowest. I may have to look further on Alibaba perhaps. I'm sure there products must exist out there. :)

Hi Andy, if you find one, please leave a comment. This is a common problem Thanks

x5 is making readings complicated. I recommend to use x10 mode only for very low-powered devices such as LED lamps which otherwise give no or a very coarse reading. For anything else x1 mode is to be used. It may be a good idea to change the switch to one that automatically toggles back into the x1 setting if you let go. That way you can't leave the unit accidentally in x10 mode

@@TheHWcave I'm not usure if I got my meaning across properly, and I've had a little bit more of a think. The 100A range is too wide for most needs, so the 10A range you have implemented is a good idea, and with the 2 range switch, it probably is the best solution. But I was just wondering what else might be done instead. What if the range could be reduced to around 15 or 20A permanently, which then covers the 10-15A range of most mains power outlets. With 5 loops, and doubling the burden resistor, you would have the 10x range and sensitivity. (roughly, it will probably be non-linear, and require fine tuning). The questions are, how much over voltage can be applied to the ADC input? and what will the firmware do with over-range ADC values? and can they be displayed? Though unlikely, but it may turn out to be possible to have a single 15A range (with the meter displaying 150A). Again, your 2 range project is probably the optimum solution. But I'm curious to explore other possibilities.

@@bertoid Of course you may change it to a x5 range. I personally have not considered it necessary. In x1 mode with currents 20mA limit of the module to measure PF which is a problem for small devices like LED lamps.

It goes into one of the thin black or red wires (does not matter which) connecting the current transformer to the module. It does NOT go into any thick brown or blue wiring carrying mains current! Adding the fuse is really more a belt-and-braces approach. It would only trigger if you measure more that 10A in x10 mode. Normal mains appliances rarely go higher than 10A in countries with 230V mains. For 120V countries, yes, adding the fuse makes more sense.

@@TheHWcave Please think, that the 1.000-windings-coil never works open. Then You will have very high Voltages in this coil. This is the case, if the fuse ist melted. So it seems to be saver, to work without a fuse. Furthermore a fuse of 0,1 A F has a resistance of several ohms.

@@HevyFilms Both are very good points. I guess a MOV across the transformer would be a good thing to add. The fuse resistance (within limits) should not make a difference because the transformer is delivering a current and the fuse is in series with the sense resistor, so both see the same current.

@@TheHWcave You dont think, that the Voltage of the Fuse has any negative effekt? If You have 10 Amperes and x10, you will have at least round about 100 mV at the fuse. Whatever, Your solution and your video is very good anyhow and I copied this device! Did You ever measured the inductance of the 10 windings throu the core? Whats about the additional phase shifting and the additional Voltage drop?

@@HevyFilms The secondary of a current transformer is providing a current which is scaled according to the current in the primary. That means the resistance is kind of irrelevant, if it is higher, the current transformer simply increases the output voltage until the target current is reached. That is the reason why it should always have a load, because otherwise it tries to scale the voltage up to infinity (well, very high...) It takes a while to get your head around. This works of course within limits. You would not put kilo ohms in series and expect no effect. It is similar to a normal transformer where you can add additional parallel resistance and within limits, the output voltage will not be affected. No I did not measure the inductance of the 10 windings, maybe I should but I am not sure if I have the tools to do it. I used pretty thick mains-rated wiring in the box, I think 1.5 square mm because I wanted to be able to handle at least 13A. To answer your question, I just measured (4-wire) the resistance of the mains path from the input socket to the output socket of the box. In x1 mode, it was about 0.1 Ohm, in x10 mode 0.45 Ohm. At 10A in x1 mode this drops 1V, in x10 mode 4.5V. I can live with that, especially since I use x10 only when the current is too low (

Fair point and well spotted. I will do that.

That is not how my unit works. Example1: A GU10 LED lamp measures in 1x mode: 0.044A, 5.84W, PF 0.55. In x10 mode: 0.425A, 57.5W, PF:0.56. Example2: A fan: x1 mode 0.181A, 30.0W , PF 0.70 in x10 mode: 1.775A, 298W PF 0.71. The values in x10 are slightly different because of the better resolution with higher values but otherwise this is exactly what I would expect. I am trying to think what could have gone wrong. I suppose you did the easier method of having two separate sense wires, a single one and one that loops 10 times, and switch between them? It is important that the 1x is completely off (no current but also not shortened) when x10 is on and vice versa. Otherwise the two can start cancelling each other.

@@TheHWcave I tried two different devices, both react identically to this hair dryer and only in the no heat mode and fan on the minimum position. Other devices follow the rule of the number of turns. I used only one wire and only made different winding combinations. the dryer model is philips 8233. funny is that it was the first device tested and it caused me confusion.

That effect would be well worth investigating. I looked at the web pages of the (discontinued) hair dryer which seems to have quite a bit of electronics on board. Ionic (does it have a high-voltage multiplier?) and possibly speed control (phase control circuitry?). If you turn the hairdryer off between changing the config, does it always start with the same values if you keep the config the same? In other words, its speed control may behave slightly different at every restart, for example because the fan turns easier if it was running earlier (warmer motor bearings & lubrication...). Do the values change (significantly) while running without anything being touched? At least at my place, the RMS AC voltage fluctuates quite a bit, so its nearly impossible to accurately compare measurements done just seconds apart. If the electronics in the fan tries to maintain speed at a fluctuating AC input, it might well modify the phase angle noticeably. Hope you can safely(!) experiment a bit more and report your findings?

At this low speed, the motor (supply circuit) use a current so constant that the transformer does not work. adding more turns only makes the power factor worse. I think there are several situations like this and a major change in the power factor from mode x1 to x10 implies an incorrect measurement. At the moment I have abandoned the project but I promise to come back with details when I finish the workbench from the location where I am moving.

Its AC so whether a current is constant or not, it will always work with the transformer, however, its RMS value may be too low for the thresholds built into the Peacefair to register. The power factor will not change with more turns through the transformer and I have never observed anything like that in my device. Something strange is going on in your build. What kind of current transformer are you using? Is it a solid ring or one that can be opened? I have recently used a current transformer that can be snapped open and on one occasion I found strange readings (current too low and a wrong power factor). On investigation, I found that the transformer ring wasn't completely closed. Making sure it was completely closed fixed that problem.

Beware, in x10 mode, the module sees 10x more current than actually flows but it does not know that of course, so the power it shows is also 10x more than what it really is. The point of x10 mode is to make it display values for tiny consumers like LED light bulbs, not whole households. If you use it you must mentally divide current and power values by 10. 60KWh seems excessive unless you are running one of those electrical fan heaters day and night ... , or maybe faulty sensor switch for the immersion heater in the hot water tank (if you have such a thing). Best, check the whole setup for accuracy by testing it against a consumer with known consumption. Incandescent light bulbs are ideal for that because they are very predictable and a 60W bulb is usually pretty close to 60W (if the mains voltage is nominal). I keep some of these bulbs around just for serving as high power load resistors.