This is how my mains looks like

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220V/50Hz country. is this good, decent, crappy? :)
 

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@rrrremus:
this is in Iasi, practically the opposite end of the country. large block of flats (88 of them), it has its own transformer station.


@Jan
measurement was taken approx at noon. powered appliances were:
- small car battery charger (SMPS powered)
- other small switch-mode supplies (2 laptop chargers and one external HDD)
- amplifier SMPS (in stand-by)
- DAC - linear supply, in stand by
- fridge
- LCD TV (on)
- gas water central
- gas sensor
- no light was on (most are economic type)

I measured at 2 different outlets in different rooms, no change. I'll remeasure with all appliances disconnected. I used laptop sound card (noise floor at ~-100dB, distortion is 2nd order at -80dB, measured with my DAC output), running off battery, obviously.
 
It's both; on the grid as well as in your house. Typical waveform spectrum now that a greater percentage of load is electronic supplies with capacitor input. Will only get worse as the world transitions out of incandescent lighting.

Normal. Typical. Unavoidable.
 
There is much speculation that these "flat topping" events are caused by the way we use our supplies and that modern technologies have made the "flat topping" worse.

What exactly is it about our modern technologies that is making the problem worse?

I note in advertising that many SMPS claim to have PFC incorporated.

Is smps with PFC really better at not flat topping our mains supplies?
How does PFC work in helping to improve our mains quality?

Note, I have lots of questions, but no answers.
 
my understanding is that what we're seeing is the effect of thousands of capacitors charging only at wave peak. thus the current waveform is anything but sinusoidal.
for me PFC is current/voltage phase. effect seen above is non-linear.
and anyway any means of making the sinked current resemble a sine would be effective only if everyone used that.
I can't imagine how this will get any better in the future :)
 
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Don't feel so bad. Here's what the mains look like in my office (University of Toronto). I only have a few computers on the same circuit.

Looks a darned sight better than what I usually see at home.. :D
I believe in addition to the issues mentioned here, that here in NA the newer pole transformers are actually saturating at the peak under even moderate loads - my line often looks very bad into the very late evening hours until all of the neighbors have gone to bed. The new transformers are about 1/3 the size of the ones they replaced and in my neighborhood one transformer powers between 10 - 12 residences. It doesn't look anything close to 100kVA..
 
It's probably your neighbours on the same floor - you all are connected in one place outside, on stairs. They have plugged in devices that have Switched Power Supply, but crappy filtering on their mains (since in Romania there is no regulation about that). Charging is visible on the sin shape. Flurescent bulbs will trow even more garbage on mains.
It happend to me once to see even worse signals (Ploiesti) and I discovered that was happening when one of my neighbours was turning on an old tube-based TV in bedroom to watch a soap opera - her husband was watching something else on the "good" TV set. The TV was "shocking" them, so they tied a copper wire to the metallic heater by window.

Also, power companies all over the world accept momentary (couple of hours) overloads of their transformers - that leads to flattening of the sin wave (mostly even order harmonics). It's better than purchasing new transformers.

Your DAC should be fine with that level of harmonics (if it has a decent stabilization/filtration stage). The only issue might be with a power amplifier, since that is just "filtered". Use 0.1uF in parallel with main caps to cut some of higher order harmonics. Some advocate the use of an external filter, but I doubt in their efficiency on high-amps power devices.
However you can look on the power rails in your devices and you will see the efficiency of your capacitors :)
 
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since in ROmania there is no regulation about that
you know that for a fact?

I see you edited your message after I posted.
I'm not concerned to the point of modifying my audio gear, just wanted to measure to see how bad it is. the way I see things this isn't necessarily a problem of that harmonic content escaping the PS (I think the most basic supply can solve that and any PS has ripple that resembles the chopped off sine tops) but actually large non-sinusoidal currents through mains wiring that can cause interference.
 
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I don't know to be an organisation equivalent of FCC to approve the electrical equipment sold in Romania. The "CE" mark regulates nothing in this aspect.
There is a maximum limit of distortion that power co needs to satisfy (that's why they frown upon people using welding machines in apartmants :)), but higher harmonics are not really their fault. It is called "regim deformant".... Look for "PE143/2001 - Normativ privind limitarea regimului deformant".

Disclaimer: it is more than 10 years since my "Electrician Autorizat Gradul IV" expired so I might not be up-to-date :)
And yes, I always I edit my posts :(.
 
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this may have changed when we entered the European Union. even if so, older equipment may still be in use.
I don't know how this works but what escapes me is: even if one lives in a regulated country, what prevents one from buying equipment made for non-regulated countries? obviously that would be a small percentage but nevertheless.
 
Active power factor correction will draw sinusoidal current from the mains, so does not cause the flat-topping effect seen here and at every one else's house (you just haven't checked it yet).

Problem is the cost of that controller is such that it is only used on the high powered DC supplies, such as server equipment. Few residential grade devices have PFC front ends. Certainly not your residential fluorescent or LED lighting replacement bulbs. Not your plasma TV or computer or router or WAP or ipod charger or cell phone dock or alarm clock or telephone or printer or scanner or receiver or cable box or Xbox or Wii or HT amp or etc etc etc etc.
 
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