It is unusual to have large Neutral currents on a gen system on the basis that all three phases should be evenly loaded to keep the Neutral currents to a minimum.
To answer your question, the max Neutral current allowable on a standard gen set would be a value not exceeding the max phase current value or rather the gen flc.
There are no standards which quantify these values as it is upto the user to ensure that the gen and the distribution system is designed to operate safely.
Another point that may add to this topic, is the pressence of third harmonic in the load current. For example, with discharge lamps, the value of third harmoic in each phase current is about 20 to 30 % , this will make a value of 60 to 90 % of third harmoic current in the neutral. Noting that the load is totaly balanced.
Thanks everyone for your responses. I was not specific, I was referring to high currents from the neutral to the ground of DG, at no load, leakage current is 1% and at half load, 5%, seems like leakage current increases with load..does this phenomena confirm that there's a leakage in the stator and is there any standards stating the allowable leakage current?
