triplen currents?

[emadshaaban]

hi all
How much important tacking in considration triplen current How could i calculate triplen current flows in neutral,to chose the neutral cable size?
What kind of loads create it ?
Is the electronic ballast of lighting creates triplen ??
Thank you.

 

[emadshaaban]

any reply

 

[cuky2000]

General Comment Triplen current or better known as third harmonics in the ANSI marketplaces are the odd harmonic current multiples of the 3rd harmonic (ex. 3rd, 9th, 15th, 21st etc.). Tunned filters may be used to mitigate the impact of large harmonic distorsion to maintain a desired power quality performance in term of total voltage and current distorsion or individual harmonics that may exceed the recommended limit.

How much important tacking in considration triplen current? This harmonic is related with the zero sequence and therefore impact the size of the neutral conductor, overheating transformers, motors, cables, etc. There are documented cases that this current could cause mis-operations of relays, protective devices or control units.

How could i calculate triplen current flows in neutral,to chose the neutral cable size? Perfoming a harmonic analysis using guidelines from standard such as IEEE-519, IEEE-1547, EN 61000, AS2279, BS G5/4, etc. There are several commercial software in the market that could facilitate this analysis.

What kind of loads create it ? None linear load including flurescent lighting ballasts,dimmers, computers, UPS, rectifiers, variable freq drives,battery chargers, etc.

 

[ScottyUK]

Single phase non-linear loads are contributors - 3-phase rectfiers and converters are generally connected across three lines with no neutral, and the dominant harmonics are 5th, 7th, 11th.


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If we learn from our mistakes I'm getting a great education!

 

[emadshaaban]

thank you cuky,for your efforts to help.
But when i have inductive load how could i find how many amps gona be created?
Is the star connection of feeder transformer helps to create triplen.
Is the sig zag connection prevents the triplen to create?
Thx

 

[emadshaaban]

i found an power hormmaic analyzer.but the result with presentage(%).what does it mean?

 

[waross]

"But when i have inductive load how could i find how many amps gona be created?".
Inductive loads do not create harmonic currents. Non-linear loads create harmonic currents.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jghrist]

i found an power hormmaic analyzer.but the result with presentage(%).what does it mean?

It means that the measured quantity (voltage or current) has a harmonic magnitude for a particular harmonic order that is the measured percentage of the fundamental quantity. Or, if is THD (Total Harmonic Distortion), it is a calculated measure of the square root of the sum of the squares of all of the harmonics as a percentage of the fundamental.

 

[emadshaaban]

thank you.
How can i get the value of triplen current from the hormmoic presentage.?and is usefule to know the order of this hormmonic?

 

[jghrist]

Triplen harmonics are those with harmonic orders that are multiples of three. You can get the current by multiplying the percentage of fundamental current by the fundamental current.

 

[emadshaaban]

thank you. V match

 

[busbar]

Check out back issues of EC&M magazine. {

http://www.ecmweb.com

} There have been numerous articles on triplen and other power-system harmonics. One caveat—the online material is without charts, photos or illustrations. You have to purchase the articles to get those.

 

[emadshaaban]

thank you alot

 

[stevenal]

My IEEE dictionary says a triplen is an order of harmonic that is a multiple of three. Not sure why you would want to stick with only odd multiples, since even multiples (6th, 12th) would also add in the neutral. May not be common in power systems, but that is no reason to exclude them from the definition.

 

[busbar]

Steve, don’t even-order harmonics indicate DC offset in the waveform? That would seem to present its own set of problems.

 

[stevenal]

A waveform containing even harmonics is not symmetrical from one half cycle of fundamental to the next. DC may or may not be present. A half wave rectifier would cause both DC and even harmonics.