Harmonic affects

[iwire]

Part of my job is to educate consultant engineers about new issues. The problem with electricity is that people think nothing changed since Edison's light bulb. Well, it is. 90% of the consultant engineers don't know much about harmonics. I can't expect more from simple electrician.

I would not expect a engineer who has products to sell to feel any other way.

 

[Besoeker]

Harmonic issues in residencies, I find that very hard to believe.

To answer your question about wiring.
In my street there is a local distribution transformer - it is about a 1500 kVA, 11kV to 400/230V with a delta primary and star (Y) secondary. The The houses are fed with the single phase line to neutral 230V and loading is distributed around the phases.
So, low voltage single phase derived from a higher voltage three-phase supply. I perhaps ought to add that there is no heavy industry anywhere near us.
We are quite close to our local transformer so the voltage we get is probably not greatly dissimilar to that at the transformer terminals.
And it contains quite a high proportion (about 4%) of third harmonic distortion. That much is immediately evident from the flattened top in the waveform. There was a bit of seventh and a spread of the other usual suspects. This taken today at around 5:30 pm local time.

Does it cause me problems?
I can't say for sure that it does. I've had a couple of conventional ballasts fail in the same fitting the past year. It's the only conventional ballast we have. One of the lights in our hallway has failed just a bit more often than I would have expected. It could all be coincidence of course. If this pattern is replicated in a number of houses fed from that same supply then it just might be stretching that coincidence. I don't know whether it has - as a rule, failure of ballasts and quality of supply isn't something that comes up in casual conversation with the neighbours.:grin:

But one thing about which there is no doubt is that our supply has significant harmonic distortion the cause of which exactly fits with the proliferation of single-phase non-linear loads.

I'm pretty sure there is similar distortion on some or many other supplies in residential locations. In fact, at the pumping station I mentioned a few posts back, the average over a 24-hour monitoring period was 3.67% and for the 10pm to midnight slot it was 4.15%.

 

[brian john]

. I can't expect more from simple electrician.

Why thank you for the compliment! From the Dale Carnegie School I assume?

 

[don_resqcapt19]

...
I'm pretty sure there is similar distortion on some or many other supplies in residential locations. In fact, at the pumping station ...

Would you expect to see the same issues on a 120/240 volt single phase supply to a dwelling unit? That is the typical installation here, although there are some dwelling units that are served with two ungrounded and a grounded conductor from a 208Y/120 volt system. My home, along with 7 others is fed from a 50 kva single phase transformer.

 

[brian john]

Would you expect to see the same issues on a 120/240 volt single phase supply to a dwelling unit? That is the typical installation here, although there are some dwelling units that are served with two ungrounded and a grounded conductor from a 208Y/120 volt system.

I use to belong to a PQ group and one issue some of the utility guys brought up, was whether there would be an issue as HVAC units changed over to soft starts or VFD's for compressors and fans, this in conjunction with with a large number of chargers for electric cars.

 

[don_resqcapt19]

...
Part of my job is to educate consultant engineers about new issues. The problem with electricity is that people think nothing changed since Edison's light bulb. Well, it is. 90% of the consultant engineers don't know much about harmonics. I can't expect more from simple electrician.

And I will say again, most of the information out there about the problems caused by harmonics, is written by those who have a vested economic interest in solving those problems.

 

[Besoeker]

Would you expect to see the same issues on a 120/240 volt single phase supply to a dwelling unit?

Yes, I would if there was a significant non-linear component in the loading. I don't think that aspect of it would be much different to UK. There is similar equipment in the home that takes non-linear current - televisions, computers, dimmers, drives on washing machines, chargers etc.

That is the typical installation here, although there are some dwelling units that are served with two ungrounded and a grounded conductor from a 208Y/120 volt system. My home, along with 7 others is fed from a 50 kva single phase transformer.

I have some idea of how it is in the USA too - we have a house there and lots of family..

 

[don_resqcapt19]

I use to belong to a PQ group and one issue some of the utility guys brought up, was whether there would be an issue as HVAC units changed over to soft starts or VFD's for compressors and fans, this in conjunction with with a large number of chargers for electric cars.

Brian,
So did the group determine that it would be an issue?

 

[don_resqcapt19]

Yes, I would if there was a significant non-linear component in the loading. I don't think that aspect of it would be much different to UK. There is similar equipment in the home that takes non-linear current - televisions, computers, dimmers, drives on washing machines, chargers etc. ...

My understanding is that one thing we won't see on a single phase system is the overloaded neutral conductors as a result of the harmonic currents that are additive in 3 phase systems.

 

[brian john]

Brian,
So did the group determine that it would be an issue?

No consensus was reached, as many felt that manufactures would address the issue
others felt it was a none issues and some thought the system could not handle the changes.

 

[iwire]

No consensus was reached, as many felt that manufactures would address the issue
others felt it was a none issues and some thought the system could not handle the changes.

Sounds like here.

 

[brian john]

And I will say again, most of the information out there about the problems caused by harmonics, is written by those who have a vested economic interest in solving those problems.

Just as PQ issues that are not harmonics must be related to grounding and there is a long list of products for sale out there to alleviate this perceived problem.

 

[PowerQualityDoctor]

And I will say again, most of the information out there about the problems caused by harmonics, is written by those who have a vested economic interest in solving those problems.

... and have a lot of experience in seeing such places...

I have noticed that doctors always says that there are sicknesses. Well, I don't believe them. They have an economic interest.

 

[iwire]

I have noticed that doctors always says that there are sicknesses. Well, I don't believe them. They have an economic interest.

Poor choice of analogy, there are stories in the news all the time about doctors defrauding insurance companies.

 

[PowerQualityDoctor]

Poor choice of analogy, there are stories in the news all the time about doctors defrauding insurance companies.

If you are suspicious with all doctors, I am flattered to be suspected by you. Have you ever being told that you are too paranoid?

Yes, there are dishonest doctors, yes there are dishonest engineers. I trust that you have met some dishonest electrical technicians (or more than some). Are you trustful?

Give some trust to people. Most of them deserve it.

 

[ohmhead]

I am still here to watch, I don't post my knowledge anymore on the forum.
I do reply to questions people send me in PM.

Well lets talk PF doc in a area of 50 hz would this be more of a issue with PF then in a 60 hz area my thinking is it would be ?

400 hz was designed to eliminate wire and inductance would not a higher frequency be more effective in inductance mainly for aircraft & military but now commercially ?


Question i asked this on another thread but it was never answered capacitance in a PF device used can these fix capacitors add to a harmonic condition meaning become a resonant tuned circuit at some harmonic level of the 3rd 4th 5th if not please explain why not.



Iam willing to learn more as a field electrician and have questions for you this might help us understand PF dont get me wrong i know PF is a issue and yes i know about the old Edisons days .


Lets have a question and answer on the real issues of PF you may change my thinking on some points which i may not see at this time .

 

[mivey]

Brian, I don't have much of a life. :grin::grin::grin:

Roger

I can't believe that. I'm going with a big brain. :grin:

 

[mivey]

Question i asked this on another thread but it was never answered.

See #28 & #29

...To answer the first part of your question, yes...

What he said.

I might add...

 

[mivey]

Well lets talk PF doc in a area of 50 hz would this be more of a issue with PF then in a 60 hz area my thinking is it would be ?

I'm not sure we could necessarily say that as it would depend on the impedances and the order of the problem harmonics. The system's inductive impedance will increase with frequency and the impdeance of the capacitor will decrease with frequency. This could tend bring the two together or farther apart, depending on the values.

400 hz was designed to eliminate wire and inductance would not a higher frequency be more effective in inductance mainly for aircraft & military but now commercially ?

I understand these systems have harmonics issues as well.

 

[iwire]

If you are suspicious with all doctors, I am flattered to be suspected by you.

I live with my eyes open and am not blinded by a few letters at the end of a persons name.

Have you ever being told that you are too paranoid?

It has nothing to do with being paranoid, it has to do with always considering the source and what factors may influence the sources judgment or honesty.

Yes, there are dishonest doctors, yes there are dishonest engineers. I trust that you have met some dishonest electrical technicians (or more than some).

Of course, people are people, some good some bad.

Are you trustful?

I consider myself to have high integrity, the companies I have worked for have thought so as well.

Give some trust to people. Most of them deserve it.

But not blind trust.

Personally you have been coming across as disingenuous with your claims you have nothing to sell.