I have a mobile site with three 35KW generators.  The system is designed to power share at peak times across two of the three, with the third for maintenance purposes to allow continuity of supply. Each generator is able to have the Neutral line connected to the Earth line via a removable link, and the distribution system is such that, as long as the cabling remains physically connected, the Neutral and Earth lines remain connected at all times irrespective of status of breakers through the system. 

My understanding of the regulations will require one single generator to retain the N-E link, and the other two systems will have the link removed to avoid the possibility of harmonics and doubling up of Neutral return lines.

As the system is mobile, currently each generator is earthed via earthing rods, and the various elements across the mobile sites are also earthed using their own earthing rods and grids, with these earthing grids interconnected via separate earthing cables, as well as the obvious system earth through internal wiring.

Reading through Regulation 444.4.6, it mentions that for TN and TT systems, the system should be earthed at only one point.  My current understanding of this is tied into the next line in the regulations, which states that for TN systems the Neutral line should only be bonded once with the Earth line, and in fact number of interconnected physical earth rods isn't what that statement refers to. If this is the case and 'the system' refers to the N-E connection, would individually earthed generators with only one generator having the N-E link in place satisfy what the regulations state?