This that famous harmonic distortion?

[Behemot]

Re: This that famous harmonic distortion?

Been using it for load but can do for empty socket as well I guess. The question is if it won't smooth some of the waveforms?

[tom66]

Re: This that famous harmonic distortion?

Well, always isolate what you're testing anyway. Never the oscilloscope.

[Behemot]

Re: This that famous harmonic distortion?

There was no load.

[tom66]

Re: This that famous harmonic distortion?

It's a bad idea to isolate the oscilloscope. Always isolate the load instead.

[Behemot]

Re: This that famous harmonic distortion?

Neutral is tied to ground, before breakers, that's the norm around Europe, did not see important to mention that.

I told ya what the O-scope was measuring was not important by that time - I am not doing measurements now! Simply looking how the wave looks; probably multiplier was not set right but that does not matter. That 160V was what DMM was showing when running on battery - that made me somewhat think the output is some crap so the meter is not even able to measure it. Also wattmeter got nothing from it. So I looked at it with O-scope, you can see the result in post #22.

Differential probe seems to me like some wonderfull mantra which will save everything. Generations managed without it and I also won't buy differential probe expensive like hell for simple looking at waves and taking orientation measurements.

Another phase without any load looked OK so that confirmed for me the technique is fine and I really saw harmonic distortion by the power supplies (display has no PFC at all, ATX PSU only passive one), maybe lights (don't really know where the lights are connected in here).

joshnz: yes, would you ppl at least mind reading what I wrote? It is in the very first post, O-scope is isolated by 2kVA isolation transformer. Jeez, that's the first thing to do when measuring things like this.

[joshnz]

Re: This that famous harmonic distortion?

Hi Behemot, Do you have the scope isolated?
if so that is wrong. What you are measuring should isolated.
You should measure the output of the transformer but it will filter some of the noise from the grid.

[budm]

Re: This that famous harmonic distortion?

"I told ya several times already, I am no idiot." Who is calling you idiot, from what we see, the measurement is not done right so what you see is not truly represent the real AC wave form you are trying to look at without using the diff probe as others have pointed out or float the scope (which is dangerous and the input of the scope has to be able to handle the voltages). If you are going to get mad when we pointed out the method you are using is not right, then good luck.
Draw up the 3 wires you have on your outlet, the Phase, the Neutral (return), the safety Ground. if the Neutral is not tied to safety ground at the circuit breaker panel, then your reading between the Phase and Ground will not be valid since you will be reading the voltage through the stray capacitance of the wiring/ main transformer that supplying the power to the outlet. That P-P reading as shown that I see also tells us the reading is not done properly.
If you put AC meter between Hot and Ground, if the Neutral is tied to Ground, then you should read 230VAC. Reading of 160VAC between Phase and Ground indicates that the Neutral is not tied to safety ground or the wiring problem.

[Behemot]

Re: This that famous harmonic distortion?

What?

[Kiriakos GR]

Re: This that famous harmonic distortion?

Just take a camera and show your face.. I do not do... me..you...me...you.. dialogs with ghosts and kids.

[Behemot]

Re: This that famous harmonic distortion?

Let me ask, who are you telling me not to post anything else in my own thread? Aren't you somewhat too self-important lately?

Don!t get it wrong but as quite often, especially from you, when I ask something, I get no answer but everybody telling me how wrong I am doing it and what moron trying to kill myself I am. Thank you very much, very helpfull. I did not get the answer till now BTW.

Now when I checked different phase, distortion-free, I got pure sine wave so my idea was confirmed, thanks for making me find it myself, which is the best possible solution by the way.

So I am sorry, but such input as yours I don't really need

[Kiriakos GR]

Re: This that famous harmonic distortion?

People the man become expert in just 24 hours.
Do no post further messages.

[Behemot]

Re: This that famous harmonic distortion?

New glossary terms for you.
what's coming out from all those al cheapo UPSes.
Modified sine wave with passive PFC.

my cheap multimeter can only make like 160 V from it
Average measuring meter = Non - True RMS

OK, there was nothing new for me.

New information for you: „modified sine wave“ can mean all types of strange and sometimes pretty terrible wave types, which have absolutely nothing in commong with sine wave, other than maybe carying +- the same energy. Waves definitelly not healthy for hunreds od devices out there people often use them (or try to use them) with. And I am not talking about PSUs here but things like pumps.

My plan is to map some of it and do some experiments with it.

[Behemot]

Re: This that famous harmonic distortion?

Enjoy, APC BE550-FR. I guess active-PFC PSUs won't like this stuff…

[tom66]

Re: This that famous harmonic distortion?

Most of the cheapest meters have a diode peak detector so they are only accurate for pure sine wave that has no DC component.

[Kiriakos GR]

Re: This that famous harmonic distortion?

Anyway, I am not interested in the Vp-p value right now, will start with the waveforms itself, mostly looking after what's coming out from all those al cheapo UPSes. And it must be something, my cheap multimeter can only make like 160 V from it

New glossary terms for you.
what's coming out from all those al cheapo UPSes.
Modified sine wave with passive PFC.

my cheap multimeter can only make like 160 V from it
Average measuring meter = Non - True RMS

[tom66]

Re: This that famous harmonic distortion?

Most modern DSOs have powerful FFT features.

[japlytic]

Re: This that famous harmonic distortion?

An appropriately rated high voltage differential probe should be used for this application, which means that the oscilloscope ground is maintained for safety.
To measure mains harmonics, you would need an FFT option for your oscilloscope - there is a project for an Arduino-powered mains harmonics meter out there (although you would need to adapt the program to suit the particular LCD display).

[Behemot]

Re: This that famous harmonic distortion?

Well that is the scarcely part, luckily he did not electrocute himself.

I told ya several times already, I am no idiot. That's probably why I have survived all those tens of repairs working with hazardous voltage sources and I tend to do the same with next hundreds at least. I am not saying my methods look nice, but as usually, I don't care about the appearance, it works while safe enough.

Anyway, I am not interested in the Vp-p value right now, will start with the waveforms itself, mostly looking after what's coming out from all those al cheapo UPSes. And it must be something, my cheap multimeter can only make like 160 V from it

And oh, I got 20MHz limiter on but somethings tells me it won't make much difference

[Kiriakos GR]

Re: This that famous harmonic distortion?

By watching my pictures just realized that its impossible to make an phase to phase measurement at 380V RMS by this probe.

Single phase measurement is rather easy if you not make the mistake to connect the phase wire with the ground lead of the scope.

But these diferencial probes is up to 300 EUR, and for now I am avoiding them.

[budm]

Re: This that famous harmonic distortion?

Well that is the scarcely part, luckily he did not electrocute himself.