Measuring the Power Grid

[wil]

Yes, I know ... At this moment I would like to recover my ExactPower EP15A , one of the more clever power conditioner designs I have seen. https://www.soundstagenetwork.com/revequip/exactpower_ep15a.htm

The EP15A was simply an active corrector, adding or subtracting just what was needed to correct the actual mains system, using series feed-forward techniques. It was very effective and not expensive, unfortunately the company ceased production and service, and there is still no replacement for it. A good friend still owns mine but does not want to part with it!

Do you use any form of power conditioning?

 

[microstrip]

Micro,
What was your mains Voltage reading when it was low?

Around 216V - typically it is around 231- 233V.

Do you consider THD of 3% to be particularly high?

I do not have experience with absolute levels - but the european codes allow ut to 8% THD and 6% 5th harmonic - I should be happy!

And, can you hear the difference between 1.7 and 3%?

I do not have experience enough to answer such question. I could easily hear the effect of the PSAudio P10, but probably it also changes noise and amplitude, not just the distortion.

 

[microstrip]

Do you use any form of power conditioning?

I used in another house, never tried it in this one.

 

[wil]

Micro,
What was your mains Voltage reading when it was low?

Do you consider THD of 3% to be particularly high?
And, can you hear the difference between 1.7 and 3%?

Around 216V - typically it is around 231- 233V.



I do not have experience with absolute levels - but the european codes allow ut to 8% THD and 6% 5th harmonic - I should be happy!



I do not have experience enough to answer such question. I could easily hear the effect of the PSAudio P10, but probably it also changes noise and amplitude, not just the distortion.

The reason I ask is because you said your system was not sounding right and that you then measured 3% distortion.

Or was it the voltage drop (about 7%) that was affecting the sound quality? Or both?

Sorry for all the questions. Just trying to understand the correlation between the sq diminution and your measurements.

 

[microstrip]

The reason I ask is because you said your system was not sounding right and that you then measured 3% distortion.

Or was it the voltage drop (about 7%) that was affecting the sound quality? Or both?

Sorry for all the questions. Just trying to understand the correlation between the sq diminution and your measurements.

IMO it was the voltage drop - I am using the conrad johnson LP275m and I found that tube power amplifiers are very sensitive to voltage drop - although input and driver stages are regulated, output B+ and filaments are not regulated.

But 3% is just the limit for mains THD for hospitals and critical applications - I would be happy to have a lower value.

 

[treitz3]

Sensitive to voltage drop and overvoltage as well.

Tom

 

[Kingrex]

Rex, I'm not sure what you're saying here.

The fundamental is 50 Hz. Are you referring to the 250 Hz harmonics and are you saying it's particularly high? I have no idea as I don't know how to read this or what the Y coordinate refers to?

Yes, the 5th is the 250 hert with the spike as seen on the scope. I don't personally see much less than 3% in most houses. But that does not mean 0% might not be a lot better. Not sure if thats even possible.

 

[Holmz]

IMO it was the voltage drop - I am using the conrad johnson LP275m and I found that tube power amplifiers are very sensitive to voltage drop - although input and driver stages are regulated, output B+ and filaments are not regulated.

But 3% is just the limit for mains THD for hospitals and critical applications - I would be happy to have a lower value.

Maybe you need those to also be regulated?
Would that not be a viable solution to the problem?

 

[microstrip]

Maybe you need those to also be regulated?
Would that not be a viable solution to the problem?

Although I remember two amplifiers having regulated power supplies - the Krell Evolution amplfier and the Lamm ml2.1 - they are exceptions.

Curiously the Lamm was extremely sensitive to mains voltage, as referred by the manufacturer. A 3% variation in mains voltage could even blow tubes, I always used with with a regulator.

Regulating high power tube amplifiers would be of terrible complexity and cost, unless switching power supplies are used. I know that some amplifiers use it, but have no experience with them. Until very recently, switching power supplies were a taboo in the high-end ...

Europe is terrible in this aspect - when UK (240V mains) joined EC (formerly 220V) in order to merge systems EC adopted 230 +10% -6% for a transition period, to become 230v +/- 10% (the voltage range is 207V to 253V across the EU) - a terrible gap! And after Brexit, the UK left EU ...

In my old house mains was very stable -230 +/-2V. But it seems I have to consider some form of mains condition now.

 

[Johan K]

This is all due to wind and solar generated power. You can’t expect stable power (voltage and frequency) unless hydro electric or nuclear generated power. There is just too much variation in the solar panels and in the wind turbines. Nowadays most energy producers have recognized this problem and are putting up BIG battery packs at each solar and wind turbine sites to even out the peaks and dips in voltage, before letting it out on the power grid. Frequency however is much harder to get right and stable, specially when you have all this switching back and forward between AC and DC and back to AC. Now the power companies see even greater problems with harmonics in the super high frequency range, way out of our natural hearing range, but due in fact affects the lower frequencies as well. All this is due to DC switching devices, not seen before when power was mostly produced by nuclear, hydro, coal or other forms of very stable energy sources. Many times you hear people say, ””it was better back then””, but when it comes to power production, it WAS actually better back then.

/ Jk

 

[Holmz]

This is all due to wind and solar generated power. You can’t expect stable power (voltage and frequency) unless hydro electric or nuclear generated power. There is just too much variation in the solar panels and in the wind turbines. Nowadays most energy producers have recognized this problem and are putting up BIG battery packs at each solar and wind turbine sites to even out the peaks and dips in voltage, before letting it out on the power grid. Frequency however is much harder to get right and stable, specially when you have all this switching back and forward between AC and DC and back to AC. Now the power companies see even greater problems with harmonics in the super high frequency range, way out of our natural hearing range, but due in fact affects the lower frequencies as well. All this is due to DC switching devices, not seen before when power was mostly produced by nuclear, hydro, coal or other forms of very stable energy sources. Many times you hear people say, ””it was better back then””, but when it comes to power production, it WAS actually better back then.

/ Jk

It almost looks like a political post.
We might as well throw refugees and electric vehicles in there.

I can certainly see how a cloud or a lull in the wind reduces energy.
But a lot of big industry has moved out of the US.
However every other driveway has a Tesla, or other EV, pulling down energy from the grid.

And how much has the grid changed in the last 10, 20, 30 or 40 years? If there are more people, then there should be more load.
Also ACs were relatively absent a half century ago, whereas now almost every house has an AC running.
And handfuls of switching power supplies in each house.

It seems like there are a lot of variables and there should be some factual studies to point to in order to explain whether the fluctuations are more, and then if so, then why they have increased.
But my impression is that the infrastructure has not kept up with the required load/need??
And I do not recall rolling brownouts in decades past.

I certainly like the idea of solar and wind, but nuclear is pretty hard to beat.
And it is odd that 90% of the hard core environmentalists do not like the idea of nuclear.
There are none of those CO2 things coming out of a smoke stack, so I would have expected that the climate change crowd would abide those as an alternative to fossil fuels at least in the near term… however that group is generally anti beef (for the methane), anti this and anti that.
We certainly need some real solutions rather than a list of things that we are against.

In the mean time, everyone that does not have a battery stabilised electrical grid just seems to run a device in the house to provide some stable power.

 

[Johan K]

Totally agree with you @Holmz !
Nuclear and hydro electric power is the most stable energy source there is, both in voltage and frequency. In that stable energy you rarely have any problems at all. Everything is quiet and run smoothly.

As long as we have all these switching devices running, affecting the power grid, we’re going to have all kinds of problems… that is the basic facts.

Sometimes the best harmonic filters in the world can’t solve the problems. Filters and conditioning devices must pin-point the target issue to get rid of the problem. One can’t simply use whatever filter, and think it is good to go… -or one might end up with half of the sound / dynamics gone.

This is for sure a VERY VERY complex question, with unfortunately not many answers.

/ Jk

 

[microstrip]

IMO one very relevant aspect in the decrease of mains quality was the mandatory introduction of the switching power supplies in order to increase efficiency. I realize it is needed in order to save the planet, but it terribly increased mains distortion and pollution.

We should remember that each LED lamp we see has an attached switching supply, as well as any mobile phone charger, computer - it is hard to find anything we have bough recently and is connected to mains and does not carry a switching supply noise emitter ... I attach the EM spectra of a LED lamp and of the corresponding old incandescence lamp. Although the EM field decreases fast with distance, imagine what kind of interference is being injected directly in our mains ...

 

[Kingrex]

The voltage/frequency stability of the mains is a separate subject from noise or distortions on the mains. If you have unstable voltage, there are a couple ways to deal with it.
A battery/inverter power source. Could be an industrial Eaton UPS.
A Torus Auto Voltage Regulating transformer.

If you have distortions, there are a lot of filters out there. The voltage regulating ones I mentioned work well. A battery/Inverter is a absolute block to main distortion. It may have some of its own distortions. And can it overcome the noise from your audio Equipment.

I think most all filters are looking to clear noise from 10,000 herts up into Mega Hertz. Microstrips worst noise is around 500 hertz. That may be well below what the filters we see in audio address. Not sure. Does anyone have data on their filters range?

A quick look at the Shunyata Denali says its 50 db down at 100,000 hertz. The noise mirostrip is showing is basically gone at 5000 hertz. That to me says a Denali is doing relatively noting to filter the noise from a LED light. Rigtht?????

Isn't 500 hertz well into our hearing range. I am surprised we don't hear lights squeal.

 

[microstrip]

Are there passive solutions to remove the mains harmonics? Although I read about the possibility of using single-tuned filters I have never seen such devices.

I can easily imagine an active solution to the problem - synchronizing oscillators with the harmonic frequency to mains and adding antiphase contents of them to the mains supply - but it looks complicated to implement.

 

[wil]

I’d be interested to see what your scope would show with halogen lights replacing your LED lights?

 

[microstrip]

I’d be interested to see what your scope would show with halogen lights replacing your LED lights?

The third picture is from an halogen 230V light. Currently 12V halogen lights have switching supplies to convert 230V ac to 12V dc, the supply generates the noise. The pictures of the time of the pickup coil are also of interest - halogen first, next LED. Notice the different vertical scale - the LED amplitude is an order of magnitude higher.

 

[Holmz]

Are there passive solutions to remove the mains harmonics? Although I read about the possibility of using single-tuned filters I have never seen such devices.

Maybe notch filters for all the harmonics?

I can easily imagine an active solution to the problem - synchronizing oscillators with the harmonic frequency to mains and adding antiphase contents of them to the mains supply - but it looks complicated to implement.

That would be more difficult.

IMO one very relevant aspect in the decrease of mains quality was the mandatory introduction of the switching power supplies in order to increase efficiency. I realize it is needed in order to save the planet, but it terribly increased mains distortion and pollution.

We should remember that each LED lamp we see has an attached switching supply, as well as any mobile phone charger, computer - it is hard to find anything we have bough recently and is connected to mains and does not carry a switching supply noise emitter ... I attach the EM spectra of a LED lamp and of the corresponding old incandescence lamp. Although the EM field decreases fast with distance, imagine what kind of interference is being injected directly in our mains ...

View attachment 146358

Let’s call that EM field just a magnetic field.
And it is travelling in the ether.
The power line side has a pretty low impedance, so any ripple on there would be assumed to be pretty low.
Enough devices connected to the power might change the shape, but are we hearing any 50/50 or 100/120 Hz on the stereo?

Most people that have equipment that is letting through those hums usually have long since trashed that gear.
The fundamental is filtered out on the power supply.
One could connect the scope to the power supply rails and see what is rippling on the DC.

Better gear is often better because the power supplies are better.
They are regulated to the point that there is little ripple, or they have feedback that removes the ripple because it is a distortion with respect to the signal.
Now if one made a coil with some RCA IC, and moved the light close to it, then it might be heard.
However the RCAs are usually twisted pairs though.
XLRs would be much more immune.

I would be shoving the LED up against a TT cart.
And I have heard 50 and 100 Hz through a cart, but that was an issue with the lighting wiring in the ceiling, which I fixed.

 

[wil]

The third picture is from an halogen 230V light. Currently 12V halogen lights have switching supplies to convert 230V ac to 12V dc, the supply generates the noise. The pictures of the time of the pickup coil are also of interest - halogen first, next LED. Notice the different vertical scale - the LED amplitude is an order of magnitude higher.

View attachment 146404

View attachment 146411

I’m not clear on what I’m looking at. The first picture above is with a halogen bulb and the second picture above is with an LED?
And, with the same switching power supply, the LED bulb produces more noise?

 

[microstrip]

I’m not clear on what I’m looking at. The first picture above is with a halogen bulb and the second picture above is with an LED?
And, with the same switching power supply, the LED bulb produces more noise?

Yes, an halogen and a LED lamp, both 230Vac lamps. The LED lamp has an in built small switching supply - LEDs are low voltage DC devices.

We can have 230V and 12V halogen lamps - only the 12V ones need a switching supply.