Mains quality

[audio_tony]

I've been looking at my mains quality today. I'm not 100% sure if it's the transformer I'm using (I've yet to try another), but even loading the transformer with a 1k load makes no difference to the waveform at all.

We have two solar installations nearby (I'm in an apartment block) - and I'm waiting until it's dark to see if the waveform changes at all.

I'm using a relatively small transformer (500mA rating) with a resistive divider (100k series, 15k to ground). Input voltage is ~247vAC, output voltage is ~980mV.

The waveform and THD (around 2%) I'm seeing is the same into my audio interface or my 16 bit scope.

This has been prompted by an occasional click sound from our consumer unit which contains an anti surge device. This is a physical click sound (no breakers are tripping) and I want to monitor for surges.

EDIT: I'm aware this won't affect the sound etc. etc. The objective is to find possible spikes / surges causing an odd random click in our consumer unit.

I'm just posting this out of interest really.

 

[Speedskater]

AC power line harmonic distortion is never a problem. A component's power input stage chops it up in square wave like wave form before rectifying it.

Arcs, sparks, clicks and pops on the other hand, are.

 

[Ropeburn]

Only 2% THD? That's barely audible even if it was an audio signal. Perfectly normal for power and on the cleaner side of things. This is zero problem for any run of the mill PSU, they're specifically designed to deal with way worse dirt in your power, that's their one job.

 

[audio_tony]

Oh, I should have stated in my OP - I'm aware that this won't have any affect on the sound etc. etc. etc. (I will update it).

I was just surprised to see so much hash, as I measured at our last place and it wasn't as bad as this!

As I said in my OP - the objective here is to look for spikes / surges that might be causing a random clicking noise in our consumer unit.

 

[kyuu]

What is a "consumer unit"? Hard to tell what could be causing a click there without a clearer idea of what the device in question is.

Edit: Found it out for myself. Apparently a consumer unit is what we in the states call an "electrical panel" or "load center". Where the power comes in and you have your circuit breakers. Got it.

If you're hearing clicking there but no breakers are tripping, that's likely a circuit in the surge suppressor activating. It could be due to transient overvoltages. Would be difficult to tell for sure without installing a monitoring device to record the voltage over time. Does the clicking correlate with any devices in your home turning on or off that draw substantial power?

 

[EERecordist]

I've been thinking of doing this experiment at home as well. I have an academic interest in frequency stability too.

In the US, the mains harmonic distortion is supposed to be under 3%. There is a company Ting Labs which installs sensors in homes to detect high impedance faults, htink a spark, the same thing arc-fault interruptor breakers are supposed to do. The intent is to provide an early warning for arcs that could lead to fires. They are collecting harmonics and I think they has a press release finding harmonics up to 6%.

Inverters and switching power supplies do inject harmonics. Your pole transformer is going to filter out some.

Do you have a drawing of your whole system so we can give some ideas about the click? Do you have access to a sampling oscilloscope? It may be possible to find some settings that will trigger on a click.

 

[audio_tony]

If you're hearing clicking there but no breakers are tripping, that's likely a circuit in the surge suppressor activating. It could be due to transient overvoltages. Would be difficult to tell for sure without installing a monitoring device to record the voltage over time. Does the clicking correlate with any devices in your home turning on or off that draw substantial power?

This is what I'm trying to find out. I'm attempting to get a 'baseline measurement' and then if I see any potential issues, my plan is to involve the DNO (district network operator) - the DNO manages the electricity grid here in the UK.

Our consumer unit (see attached image) has a surge protector built in (this is to current electrical standards here).

 

[audio_tony]

Do you have a drawing of your whole system so we can give some ideas about the click? Do you have access to a sampling oscilloscope? It may be possible to find some settings that will trigger on a click.

I don't have a sampling 'scope however I have a project underway, which will use a sound card to sample the mains (via the transformer I mentioned earlier) and then a Python script which captures 20 second audio snippets for analysis (by the same script).
Not earth exactly sophisticated, but hopefully functional.

 

[Speedskater]

If you were to examine the current waveform (not easy to do) into a power amp with a linear DC supply, you might find 60 to 70 percent Harmonic Distortion.

 

[Salt]

Had clicks, audible, with an Amp, but only at running idle without input signal ... turned out it was the refrigerator's on and off ... but that's over 30 years ago...

 

[EERecordist]

I don't have a sampling 'scope however I have a project underway, which will use a sound card to sample the mains (via the transformer I mentioned earlier) and then a Python script which captures 20 second audio snippets for analysis (by the same script).
Not earth exactly sophisticated, but hopefully functional.

I misunderstood. In the US we would call it the mains breaker box. I think what you are saying is that the mains breaker box is making an audible click? I thought you were talking about a click through your audio system speakers.

I would post to an online electrician forum in your country, or contact technical support for https://elucianuk.com/. They say it's Elucian by Click! Also ask the same on yellow surge device. Maybe it's a feature, not a bug.

In the US we have Siemens, Schneider, and Emerson breakers. I'm not aware of anything that would make them click.

You could also get a stethoscope or some piezo microphones into your sound card and see if you can catch and localize it physically in the mains breaker box.

 

[Devnull]

What surge suppressor is installed in your consumer unit?

 

[pablolie]

... likely a circuit in the surge suppressor activating. It could be due to transient overvoltages. Would be difficult to tell for sure without installing a monitoring device to record the voltage over time. Does the clicking correlate with any devices in your home turning on or off that draw substantial power?

My thoughts exactly. Refrigerator cycles. A neighbor turning on a 40 year old microwave. Somebody leaving their smartphone too close to a sensitive device. Etc etc.

 

[audio_tony]

What surge suppressor is installed in your consumer unit?

It's this one.

SY2D - Type 2+3, single module, 2 pole with replaceable modules and window indication - Surge Devices

Type 2 single phase surge device ideal for domestic installations. Fully compliant to BSEN61643-11, BSEN62305 & BS7671. Visual status indication. Earth leakage free so may be connected before or after RCD's, RCBO's etc. Can be used on all installation types (TN-S, TNC-S, PME & TT). Earth...

www.surgedevices.co.uk

 

[EERecordist]

There is a slight possibility that some wiring device which is not visible from the front panel which clicks is inside the box. That's where ask electricians comes in.

 

[audio_tony]

There is a slight possibility that some wiring device which is not visible from the front panel which clicks is inside the box. That's where ask electricians comes in.

I know what's in there, I watched the electrician install it. I have mentioned the clicking to him, he reckons it can't be from the box. I disagree.

 

[Dumu]

You seem to have two circuit breakers marked "off peak" and "peak" for your water heater. Is there possibly a relay that switches between the two supplys and this is what you are hearing? It is very common to have relays inside the electrical panels and most of them makes an audible click when they change states.

 

[audio_tony]

The switching between peak and off peak is handled by the meter, which is located in a garage some distance away.

Out previous apartment had a similar meter in the same cupboard as the breakers, and that would make a healthy 'clunk' every morning at 07:30 when it switched to day rate.

 

[Dumu]

The meter probably just sends a signal that turns on the relay. I would recommend to have someone who understand what he is doing to check the insides of the panel before putting too much effort into measurements. Much more likely that the click is caused by a relay than a surge circuit.

 

[audio_tony]

The meter probably just sends a signal that turns on the relay. I would recommend to have someone who understand what he is doing to check the insides of the panel before putting too much effort into measurements. Much more likely that the click is caused by a relay than a surge circuit.

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.