Some Harmonics knowledge

[Subbu68]

Several FMs are installing UPS, Isolation Transformers etc. So why not know a little more about the EVIL (DEVIL) harmonics.

Excerpts from Engineering Standard ER01 that is on my department website for those who need a quick primer.

Should you need the full document visit www.doe.gov.ae and look for Engineering Recommendation 01 - Limits for Harmonics in the Electricity Supply System. Okay, I could upload the PDF itself. Below screenshots

We have a 400V, 50Hz system so it more or less matches India and others with 50Hz supply.

 

[mbhangui]

Several FMs are installing UPS, Isolation Transformers etc. So why not know a little more about the EVIL (DEVIL) harmonics.

Excerpts from Engineering Standard ER01 that is on my department website for those who need a quick primer.

Should you need the full document visit www.doe.gov.ae and look for Engineering Recommendation 01 - Limits for Harmonics in the Electricity Supply System. Okay, I could upload the PDF itself. Below screenshots

We have a 400V, 50Hz system so it more or less matches India and others with 50Hz supply.

+1. These are few things that I have found IME messing with the audio in the following order

1. Mixer, drill having motors with carbon brushes
1. Television set
1. LED tubelights and bulbs
2. Computers
2. UPS
3. Most SMPS based power supplies
4. Cell phone chargers

I use step down transformer instead of UPS to regulate the voltage and prefer not to listen when power supply is cut off. In my complex the generator kicks in less than a minute. Even the diesel generator gives better power supply than the so called pure sine wave ups.

 

[Subbu68]

+1. These are few things that I have found IME messing with the audio in the following order

1. Mixer, drill having motors with carbon brushes
1. Television set
1. LED tubelights and bulbs
2. Computers
2. UPS
3. Most SMPS based power supplies
4. Cell phone chargers

I use step down transformer instead of UPS to regulate the voltage and prefer not to listen when power supply is cut off. In my complex the generator kicks in less than a minute. Even the diesel generator gives better power supply than the so called pure sine wave ups.

Motors have brushes that create sparks and that's RFI. When the neighbouring "uncle" goes by in his Lamby or father comes home in his Bajaj 150 you get them on radio.

The rest the best harmonics producers EMI.

DG set is a synchronous generator that is the little brother of those in Trombay or Koradi or Chandrapur or any other PS. They don't know to generate anything other than 50Hz

 

[prem]

Subbu68, if a TV is on red phase, microwave is on yellow phase and the audio system is on blue phase, would the audio system get affected by the noise generated by the TV and the microwave since they are on separate phases?

Would other electrical gadgets and lighting on the same blue phase as the audio line corrupt the audio power line the most?

 

[mbhangui]

Subbu68, if a TV is on red phase, microwave is on yellow phase and the audio system is on blue phase, would the audio system get affected by the noise generated by the TV and the microwave since they are on separate phases?

Would other electrical gadgets and lighting on the same blue phase as the audio line corrupt the audio power line the most?

Will wait for Subbu to reply, but my guess is that the noise will propagate to all phases because all have a common neutral. Sometimes I think the only truly independent power source free of harmonics would be to have a portable Yamaha generator. But that would be a smoke producing equipment.

 

[Love4sound]

Subbu68, if a TV is on red phase, microwave is on yellow phase and the audio system is on blue phase, would the audio system get affected by the noise generated by the TV and the microwave since they are on separate phases?

Would other electrical gadgets and lighting on the same blue phase as the audio line corrupt the audio power line the most?

My tv was causing noise. So I experimented connecting it to different phase but It didn’t work. Only way to electrically disconnect your audio equipment’s from other devices is with an isolation transformer.

 

[Shinto]

Yes ,other phases will be affected.. All the three phases are part of one system tied together by the star point ( the neutral).So if there is harmonics in one of the phases, this increases the neutral /return current back to the neutral point , the system is now unbalanced(or to correctly say more unbalanced).The current harmonics from devices distorts the voltage. The result is distorted voltage waveform which intun affects sensitive equipments.

 

[Subbu68]

Subbu68, if a TV is on red phase, microwave is on yellow phase and the audio system is on blue phase, would the audio system get affected by the noise generated by the TV and the microwave since they are on separate phases?

Would other electrical gadgets and lighting on the same blue phase as the audio line corrupt the audio power line the most?

Yes ,other phases will be affected.. All the three phases are part of one system tied together by the star point ( the neutral).So if there is harmonics in one of the phases, this increases the neutral /return current back to the neutral point , the system is now unbalanced(or to correctly say more unbalanced).The current harmonics from devices distorts the voltage. The result is distorted voltage waveform which intun affects sensitive equipments.

@prem @Shinto has replied to your query.

Here the extreme effects of harmonics on equipment (over heating and damage) as described in the literature may not happen. All modern equipment have some sort of filter to keep the harmonics they inject to the minimum. These harmonic voltages do not add up arithmetically but vectorially so some 2nd harmonic injected by say your TV may be "neutralized" by SMPS of the PC if they are 180 deg apart in phase. It's not easy to gauge unless the currents and voltages are put through a harmonic analyser and complex programs. But you'd get the interference as the wiring would act as antenna transmitting it and other equipment receiving these "signals".

In residential loads it is very difficult to have perfect balanced loading of all three phases. There would be ultimately some residual current in the neutral at the transformer. This when flowing through the cables, joints and ultimately the earth pit that all have some resistance, you can have a voltage at the neutral point. This can cause a slight unbalance of voltages at the phases. But then your loading may not be the same as your neighbor's and so on . So ultimately all may balance out and neutral could be at peace.

With harmonics injected from non-linear loads, it becomes even more complex. If within the statutory limits as given in my first post, it may not have any serious effect.

 

[prem]

Thanks everyone for your inputs.

So Subbu68, is isolation transformer on the audio power line one of the better options?

I read elsewhere that nearly 75% of the junk in the house powerline is generated from within the house. Is that a fairly correct statement?

 

[Kannan]

I read elsewhere that nearly 75% of the junk in the house powerline is generated from within the house. Is that a fairly correct statement?

Depending upon the distribution topology and the type of businesses (say industrial) in the vicinity, there could be overall impact including the noisy devices in your home.
I have been using isolation transfoemer only on the outlet that powers my audio and am happy with the results. How much sonic difference it bring will be an individual experience.
Keep the isolation transformer power rating at atleast twice the load and use a matching fuse on the mains wired to the outlet.
If you alread used any stabilizer or servo, then match the power ratings accordingly.

 

[mbhangui]

The main use of isolation transformer is to isolate power line ground and thus avoid ground loops. It can also provide safety by separating the power and inadvertant shock resulting from equipment body coming in contact with live wire. The high frequency loss of the iron core also allows an isolation transformer to filter high frequency noise. When the isolation transformer is designed it is very important to pay attention to windings capacitance values which create capacitive coupling. This enables AC signal to pass from primary to the secondary side which significantly increases the noise level. For this purpose, the windings are surrounded by a metal strip which is grounded (creating a Faraday shield). It has the following applications

• High noise attenuation level even in high-frequency applications
• Suitable for higher harmonic area installation
• It can block interference caused by ground loops
• Appliances induce a high level of interference back to their power supply if the equipment needs to be protected from this noise isolation transformer can be used for their supply

So one can theoretically have two isolation transformers. One for the audio equipment alone and another for rest of the appliances, the noisy ones. This will prevent the noisy appliances from injecting noise back into your power line. How effective they are, I don't have an idea as I have never used one myself.

 

[Kannan]

Depending upon the distribution topology and the type of businesses (say industrial) in the vicinity, there could be overall impact including the noisy devices in your home.
I have been using isolation transfoemer only on the outlet that powers my audio and am happy with the results. How much sonic difference it bring will be an individual experience.
Keep the isolation transformer power rating at atleast twice the load and use a matching fuse on the mains wired to the outlet.
If you alread used any stabilizer or servo, then match the power ratings accordingly.

For whatevere it is worth, here is a short video with a device that detects line noise. It is 4 videos joined together.
The 1st part is the outlet showing higher DC noise with some electircal items switched on. The second part is lower noise with the equipments switched off.
The 3rd part is an outlet connected directly to an extension box showing some noise.
The 4th part is the same outlet with no noise after the line is passed through an isolation transformer.

 

[mbhangui]

For whatevere it is worth, here is a short video with a device that detects line noise. It is 4 videos joined together.
The 1st part is the outlet showing higher DC noise with some electircal items switched on. The second part is lower noise with the equipments switched off.
The 3rd part is an outlet connected directly to an extension box showing some noise.
The 4th part is the same outlet with no noise after the line is passed through an isolation transformer.

Unable to view because it says video is private

 

[Kannan]

Unable to view because it says video is private

please check now

 

[mbhangui]

For whatevere it is worth, here is a short video with a device that detects line noise. It is 4 videos joined together.
The 1st part is the outlet showing higher DC noise with some electircal items switched on. The second part is lower noise with the equipments switched off.
The 3rd part is an outlet connected directly to an extension box showing some noise.
The 4th part is the same outlet with no noise after the line is passed through an isolation transformer.

Is this line noise detector available somewhere? It is very clear from the video that isolation transformer helps. It should cost around 20k or so. @Love4sound got one recently from Vertex.

 

[Love4sound]

Is this line noise detector available somewhere? It is very clear from the video that isolation transformer helps. It should cost around 20k or so. @Love4sound got one recently from Vertex.

It was Kannan’s Isolation Transformer I got home to test before finalising. For sure I won’t be able to continue with my hobby if not for isolation transformer

 

[prem]

I have miniature circuit breaker at the main panel feeding 8 LED lights, two fans and two plug points. If I want to prevent rf and emi coming back into the power line, should I connect a emi rf filter just after the miniature circuit breaker at the main panel in series?

Will it help?

In the past I have tried various stuff on the audio power line. From Plitron balanced transformer to CVT to Shunyata Hydra to Powerwing to RSA Haley to PS Audio regenerator. I haven’t liked any. While they all did varying levels of clean up, I lost out on macro dynamics and timbre. I always ended up preferring direct to wall because all these power conditioning products kind of sterilised the sound a bit. So now I am trying reducing rf and emi coming back from other gadgets into the power line.

 

[Subbu68]

Thanks to all your queries and posts FMs on power network related issues, I started reading more on harmonics, voltage unbalances, flicker etc. etc..

Now these special reads have helped me to catch some non-compliances

I have miniature circuit breaker at the main panel feeding 8 LED lights, two fans and two plug points. If I want to prevent rf and emi coming back into the power line, should I connect a emi rf filter just after the miniature circuit breaker at the main panel in series?

Will it help?

In the past I have tried various stuff on the audio power line. From Plitron balanced transformer to CVT to Shunyata Hydra to Powerwing to RSA Haley to PS Audio regenerator. I haven’t liked any. While they all did varying levels of clean up, I lost out on macro dynamics and timbre. I always ended up preferring direct to wall because all these power conditioning products kind of sterilised the sound a bit. So now I am trying reducing rf and emi coming back from other gadgets into the power line.

To prevent feedback of EMI, I think filter should be as you said.

That said, you must have seen the ferrite beads in PC chargers, older mobile chargers etc. They prevent EMI/ RF from going back to the network too if I understood correct.

Why don't you try them on the wires to the LED lamps?

 

[prem]

I am experimenting with Ferrite beads also

 

[Subbu68]

I am experimenting with Ferrite beads also

Post your findings please. We could benefit from it.