Harmonics, Electronics, Neutrals

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Don't believe everything copper org has to say.

Their mission is not the betterment of the electrical trade, their mission is furthering the sale of copper .... period.

Would you ask Caterpillar who makes the best heavy equipment?
 
iwire said:
Don't believe everything copper org has to say.

Their mission is not the betterment of the electrical trade, their mission is furthering the sale of copper .... period.

Would you ask Caterpillar who makes the best heavy equipment?
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Where did that come from Bob? I didn't mention copper.org.?
 
76nemo said:
Where did that come from Bob? I didn't mention copper.org.?
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:grin:

Dude, it's not all about you. :D


MDs link was to copper org (which he mentioned) but also if you read an article in EC&M (or any other trade mag, Internet paper etc.) about harmonics often the author of the article will not be a electronics engineer but an engineer working for a wire company or surprise surprise .... copper org.

Don't misunderstand me, it's not that I do not believe harmonic currents exist, or that in extremely poorly deigned electrical systems those currents can be damaging.

It is just that much of it has been overblown, and much of it is 'what if' not 'this happened'.
 
iwire said:
:grin:




MDs link was to copper org (which he mentioned) but also if you read an article in EC&M (or any other trade mag, Internet paper etc.) about harmonics often the author of the article will not be a electronics engineer but an engineer working for a wire company or surprise surprise .... copper org.
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No, tell me it's not true. You mean all these guys are biased because the entities they represent could benefit monetarily if they get us to go with their recommendations? :D

Roger
 
iwire said:
...It is just that much of it has been overblown, and much of it is 'what if' not 'this happened'.
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Bob ,..you know I love to read,.. post a link to a paper or an article that demonstrates the overblownedness:-? of this issue...
 
so far we are discussing the amperage of the neutral because of harmonics..we are discussing the need to up size the wire..yet on a design like this it is really about the computer equipment and not the wire..the examination of installation costs alone are not enough..what about the massive amount of computer equipment on the circuit..I doubt we a talking 4 or 5 computers..we are probably talking 100 plus computers and all the gadgets that go with them..how does harmonics effect them..can the owner sue you for improper design when the shelf life of his computers are cut in half because of minimum design..because we based our install on minimum neutral size alone..

Just curious if you can tell the effects of monitor life alone with high harmonics..
 
cschmid said:
so far we are discussing the amperage of the neutral because of harmonics..we are discussing the need to up size the wire..yet on a design like this it is really about the computer equipment and not the wire..the examination of installation costs alone are not enough..what about the massive amount of computer equipment on the circuit..I doubt we a talking 4 or 5 computers..we are probably talking 100 plus computers and all the gadgets that go with them..how does harmonics effect them..can the owner sue you for improper design when the shelf life of his computers are cut in half because of minimum design..because we based our install on minimum neutral size alone..

Just curious if you can tell the effects of monitor life alone with high harmonics..
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Well, if there are problems, the owner should go after the computer manufacturers for not correcting the problems their equipment causes on the electrical system.

Are we going to change to service conductors to the building to include individual neutrals for each phase conductor?

Of course we could use Don's proposed solution (from past threads) and feed all electronic equipment with single phase transformers.

Roger
 
Most computer power supply manufacturers are doing a better job with harmonics and power factor problems that they used to cause.
In the US, we have harmonic limitations placed at the service level (point of common coupling), and individual devices can run rampant. In Europe they have power quality limitations at the equipment/device level, so in trying to comply with European product requirements, there are power factor correction Incorporated into the power supply and most manufacturers sell the same product here in the US, so we get better power supplies as a byproduct.
 
M.D.
I have never seen any article about the problems of harmonics that was not written by someone with a vested economic interest in solving the problem. I also have not read any documented cases of such problems in normal office or other commerical occupancies. (I am not including large data centers or communications centers in the definition of "normal")
 
I have stated this before and while I am not an engineer nor an expert I have some experience going back to the days electricians first realized harmonics were related to loads and not music.(A little humor cut me some slack) and yes I know there are articles regarding harmonics printed long before switch mode power supplies became the HOT TOPIC or for that matter even invented.

I have completed numerous harmonic surveys, primarily for customers that were told their equipment problem was harmonics. What I found was primarily wiring issues; multi-wire branch circuit all ungrounded conductors on one or two phases. Grounding issues, neutrals grounded downstream of the main neutral to ground bond and then there is voltage drop. A few cases of overloaded transformers in Casino's and call centers. In these cases the neutral current was equal to or SLIGHTLY higher that the phase current, we did not investigate possible branch circuit wiring issues to determine if part of the overloaded neutral was related to wiring issues. One of the major issues I have seen is with generators and their handling of high harmonic content loads.

What I have seen for the most part and bear in mind while I have traveled some in this work most of my experience is in the Richmond/Washington/ Baltimore corridor. Most transformers are lightly loaded typically 1/3 capacity, most branch circuits are in the same situation, lightly loaded (electricians and/or engineers for the most part err on the light side though they do under size conductors in relation to VD). Every so often we will find a properly installed 12/4 multi-wire branch circuit loaded to the max and the neutral current is in the range of the phase currents. With the properly wired multi-wire branch circuits that I remember I have never seen neutral currents reported in some journal articles, I have read 1.732 times, 2 times, and worse case scenario of 3 times. As far as I remember all the articles stated that theoretically the excessive current were possible.

Does that mean this issue does not exist NO, just basing this on what I have seen. I am a hands on kind of guy.
 
brother said:
Just trying to get a better understanding of Electroncis Harmonics and Shared Neutrals. Im told when dealing with mostly with electronics, even though there you have a 'full boat, (ie black red blue, 3 phase) you still need/should UPSIZE the neutral because of the harmonics on electronics. In just resistive loads, it ok to leave the neutral the same size.

Is this true, been searching for more info, but having trouble. Im not much of an electronics guy.
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The oversized neutral issue on THREE PHASE CIRCUITS started long before non-linear, switching power supplies were even invented. The issue started with three phase HID and fluorescent ballasts. If you run individual neutrals with each single phase circuit, you will never have an issue.

The SqRt^3 may not be a solution for shared neutrals either.

If you have a mixture of three phase and single phase loads you may not need oversized neutrals, but it is of course hard to predict. If you only have single phase loads, use 3 single phase transformers with individual single phase panels for non-linear loads. It may not be the most economical solution, but on the long run it is the cleanest installation that will stay without neutral troubles even in the future when the installer wasn't somebody how paid attention. The other benefit of single phase panels that there is no inadvertent L/L voltage hook up. (Been there, seen it.)

Often it is not the initial installation that gets people into trouble, but the 'aftermarket' 'nonqualified installers who throw the ballanced phase installation into the wind and create all sort of voltage issues as the result.
 
The other benefit of single phase panels that there is no inadvertent L/L voltage hook up. (Been there, seen it.)
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208/240 on a 120 vac branch circuit?

I have seen the single phase 120 VAC panel install. What about single phase 240/120 3 wire? Also a PDU with secondary that was Wye Wye?
 
don_resqcapt19 said:
M.D.
I have never seen any article about the problems of harmonics that was not written by someone with a vested economic interest in solving the problem. I also have not read any documented cases of such problems in normal office or other commerical occupancies. (I am not including large data centers or communications centers in the definition of "normal")
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This being the United States and all I'm a little surprised that no one has written a
"Don't be taken in by the copper industry,.. super neutrals ,..super nonsense" type article no big deal ... It would be nice to see is all ...
No one likes to spend money they don't have to.
 
M. D. said:
This being the United States and all I'm a little surprised that no one has written a
"Don't be taken in by the copper industry,.. super neutrals ,..super nonsense" type article no big deal ... It would be nice to see is all ...
No one likes to spend money they don't have to.
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What are you doing tomorrow? You write pretty well. :D


Roger
 
cschmid said:
why worry the NEC is headed to no MWBC anyway so this will be non issue.
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Yep, it's true, and the effective date has been set,
IHIWSBIWHMB said:
Multi-Wire Branch Circuits's (Edison Circuits) shall be prohibited on the day Roger wins the Power Ball lottery
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so as you can see, the days of using MWBC's are short lived, but I wouldn't hold my breath if I were you.:D

Roger
 
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