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#1
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Sidumisile Tshuma
09-26-2013 02:22 AM

What could be the main cause of the earth neutral voltage to be high

What could be the main cause of the earth neutral voltage to be high, for example 20V on a 230V installation?
09-26-2013 05:17 AM
Top #2
Mark Hurlburt
09-26-2013 05:17 AM
Unbalance or unequal loads on the wye connected output side
09-26-2013 07:36 AM
Top #3
Raymond Lee
09-26-2013 07:36 AM
If this a three phase system, thete must be neutral current flowing.

Neutral current can be fundamental ad stated already from unbalanced load or from zero sequence current.

While neutral vurrents above is not uncommon, thevoltage is if the neutral ground reference has high resistance path to ground and neutral current flow in this path to produce a voltage drop that,is noticeable, as in your case.

Check out your neutral ground system.
09-26-2013 10:00 AM
Top #4
Jim Knoch
09-26-2013 10:00 AM
If you are powering a variable frequency drive, you will likely have considerable 3rd harmonic currents in the neutral ... if the neutral is sized smaller than the phase conductors you may be having a voltage drop issue which is pulling your grounding network to a potential above earth ground possibly even overloading the grounding conductors.

If this is a delta 230V, then it may be the impedance of the zigzag transformer forming your neutral grounding point with the neutral current flow.

Measure the grounding current and neutral current flow for either situation.
09-26-2013 12:04 PM
Top #5
Prashant Ranadive
09-26-2013 12:04 PM
Earthing path is improper, having high resistance path or loose connection.
09-26-2013 02:13 PM
Top #6
Meng-Ho. Ngu
09-26-2013 02:13 PM
Sidumisile, I checked your profile in order to see which country you are currently located.

Now I can assume that the voltage of 230V must be a single-phase, 2-wire at your installation. Please correct me if I am making a wrong assumption.

Your power source star/neutral point should be grounded. The load current that your installation is consuming must return through the neutral wire. The 20V measured at your installation's neutral wire with respect to the ground is the voltage due to the current flowing back to the source's neutral.
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