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help plz neutral harmonics

help plz neutral harmonics

help plz neutral harmonics

(OP)
I monitored a commercial building for one week and the harmonics (neutral) result as:
THDv(N)=31.2% && 3rd harmonic=21.89%
THDi (N)= 194.4% && 3rd harmonic= 186.8%

could anyone tell me what are they mean and how to mitigate them..

thanks

RE: help plz neutral harmonics

That means that the third harmonics combine in the neutral. It also means that you have lots of computers or other non-linear loads connected from L to N.

The percentage is not a problem. The question is how many amps you measure in the neutral. Of course, if you got 32% THDv, it doesn't look good.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: help plz neutral harmonics

(OP)
thanks alot
the maximum amps in neutral is about 150A at rush work hour

RE: help plz neutral harmonics

Does the neutral run hot?

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: help plz neutral harmonics

As Skogs is alluding to, what matters is the size of the cable. If you've got 150A running in a 16mm cable then you've got a problem. If the same current is running in a 70mm cable, then it is not an issue; with the caveat that as long as your voltage harmonics on the phase voltages are not excessive.

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