Mains quality

[pkane]

I measured my AC line a few years back. The result:

 

[Dumu]

There are no relays in the panel. The meter itself has a contactor built in to handle the load.

In my past life (40 years ago), I did a fair amount of electrical work - I don't do any these days, as I've not kept up with the regulations.

I watched the electrician install the panel - I know exactly what has gone into it.

Interesting. In Finland we only have small contacts on the meters and contactors are installed in the panels. If you know what is inside the panel then I guess it might really be the surge protector.
When working as an electrician years ago we sometimes were able to loan analyzer from the network company if we suspected problems in the grid, might be worth checking if they would be willing to help?

 

[audio_tony]

When working as an electrician years ago we sometimes were able to loan analyzer from the network company if we suspected problems in the grid, might be worth checking if they would be willing to help?

I was trying to build up some sort of preliminary case before involving our DNO (district network operator) as I do wonder if it's grid related.

I have been monitoring it for several days now, and despite hearing the clicking, nothing has shown up on my (crude) monitor (unsurprisingly).

But I'm convinced the issue started following a neighbour's solar installation (I'm in an apartment block, and all meters and incoming 3 phase supply are in a garage area, so any interference / spikes from the solar inverter are a distinct possibility).

 

[audio_tony]

I measured my AC line a few years back. The result:

Gosh that's pretty grim! Worse than mine!

What method did you use to measure yours? I'm just using a basic step down transformer into a sound card (with some attenuation of course).

 

[kyuu]

Gosh that's pretty grim! Worse than mine!

Is it? I mean if we wanted to listen to that sweet sweet 50/60Hz hum with high fidelity then that would be awful, sure. But it seems pretty normal for an electrical grid and I don't think the low SINAD will have any detrimental effect on most electrical or electronic devices.

 

[sergeauckland]

THD of 3% or -30dB is normal for mains, at least around here, and it's of no consequence. Harmonics are massively created by mains rectifiers, and filtered out by the power supply. The higher the harmonic number, the easier it is removed. There's no requirement or benefit to low distortion mains.

S

 

[audio_tony]

@sergeauckland @kyuu as I stated in my OP, this has nothing to do with audio quality etc. etc. I know that the PSU in any gear will filter out mains distortion etc., but that is not the issue here.

As I also previously stated, this is about a clicking noise from my mains board / consumer unit (call it what you will) which I believe is originating from the surge protector.

 

[kyuu]

@sergeauckland @kyuu as I stated in my OP, this has nothing to do with audio quality etc. etc. I know that the PSU in any gear will filter out mains distortion etc., but that is not the issue here.

As I also previously stated, this is about a clicking noise from my mains board / consumer unit (call it what you will) which I believe is originating from the surge protector.

Yes, the point I was trying to convey is that while it looks bad to the eye there isn't any reason to think that the noise/distortion on the mains would be causing an issue with electronics or electrical devices that might explain your clicking issue.

 

[danadam]

I measured my AC line a few years back. The result:

Looks musical

 

[audio_tony]

Yes, the point I was trying to convey is that while it looks bad to the eye there isn't any reason to think that the noise/distortion on the mains would be causing an issue with electronics or electrical devices that might explain your clicking issue.

Understood. My thoughts were that there may be some spikes which may not be enough to trigger the surge protector, but may cause some other odd side effect. Sometimes it's such a sharp click, it almost sounds like a sort arc.

 

[pkane]

Looks musical

The soundstage is not to be believed!

 

[pkane]

Gosh that's pretty grim! Worse than mine!

What method did you use to measure yours? I'm just using a basic step down transformer into a sound card (with some attenuation of course).

One of these: OneAC Line Viewer 103 but purchased from fleaBay for much less than $100. Don't know who thought $3.5k was a reasonable asking price

 

[Devnull]

THD of 3% or -30dB is normal for mains, at least around here, and it's of no consequence. Harmonics are massively created by mains rectifiers, and filtered out by the power supply. The higher the harmonic number, the easier it is removed. There's no requirement or benefit to low distortion mains.

S

Actually the UK has a little stricter THD requirements than the US at delivery voltages. IIRC low voltage, <1k, is 5% max, while the US max's at 8%, the US level was increased from 5% about 10 years ago. As the voltage gets higher the allowable THD goes down to 3% at transmission levels, while the US is down to 1.5%.

 

[Owl]

I wonder if that increased THD allowance in the US is due to all the invertors plugged into the grid now. Switching frequency and quality are all over the place.

 

[RayDunzl]

Just for grins, can you post that with a linear instead of log scale for amplitude?

 

[pkane]

Just for grins, can you post that with a linear instead of log scale for amplitude?

I’d have to redo the measurement, this was from a few years ago.

 

[Devnull]

I wonder if that increased THD allowance in the US is due to all the invertors plugged into the grid now. Switching frequency and quality are all over the place.

Exactly correct. Most inverters are grid following, wind farms, solar and end user consumer grade. They follow the voltage injecting current into the grid. Because of this they can actually amplify any existing distortion on the grid. At transmission voltage levels, > 115kv (?) at the tie point, they're allowed more than 1.5% THD as long as it's attenuated before it gets to the customer.

 

[audio_tony]

Just for grins, can you post that with a linear instead of log scale for amplitude?

Here's mine with both log and linear scales.

 

[RayDunzl]

Yup...

 

[niamex]

Hello everyone around, I am a newbee and not sure that is the right place to ask my question,so please exuse me. Maybe sound stupid but I want to ask your opinion whether delivering low voltage power /say 12 V/ from a simple PSU /transformer, diodes and capacitors/ to an unit which already has some linear voltage regulators supplying power to various IC's on the board will benefit from feeding it with 12 V from some expensive ultra linear PS ?
Thanks in advance for your attnetion