the neutral when it isn't neutral

Well in an industry or a home's installation, the phases are get with a neutral wire which it's the wire attached in the transformer's center star and that point is put at ground (literaly). Due the current armonic distortion, the neutral can has a potential with respect ground. What value can get that differential potential? I know that if there is resonation it can have more than 220V. There is a table of it? The odd armonic in neutral are the problem here. What voltage peak can be?

Different countries have different regulations.
But for the EU they are very concerned with harmonics in the neutral line.

There is a EU standard IEC1000-3-2 which deals with this topic. It will explain in excruciating detail what the maximum levels should be.


I read that standard many years ago, and cannot recall much other than the measurement bandwidth is 39 harmonics for 50 Hz, and 33 harmonics for 60 Hz. In other words, a measurement bandwidth of around 2 Khz.

Hi,

I don't have an exact answer for you, juse some informations for EU regulations.

In neutral there may be current....but the current won't be higher than the line currents (in a very extreme, but not realistic: the sum of) the three lines.

Usually the line currents sum to zero.
But (only) harmonics which frequencies are a multiple of 3 times main frequency really add up to become larger.
******
Now to voltage values:
Harmonic voltage is limited according "EN 50160 " o.
Let's focus on the overtones with 3xmainsfrequency.
3: 5%
9: 1.5%
15: 0.5%
21: 0.5%
All others sume to zero.
In total they give 5.27% RMS.
*****
DIN VDE 0100-200 defines (besides others) that the voktage between N and EarthGround must never exceed dangerous voltage.
I assume 50V AC.

Klaus