What is an exciter stator

Determine the interconnection of a synchronous generator

Hello dear people,

This is about a synchronous generator (1100kVA). It is star-connected on the stator side, so it has 3 conductors and an N conductor. Now I wanted to determine the harmonics of the voltages induced in the stator with a mains analyzer (GSC53A, quite old device). I have the option of measuring the voltage in the low-voltage main distribution. However, there are only 3 conductors (see Appendix) L1, L2 and L3. Now I don't know whether it is a 3-wire system and the N-wire is grounded or whether the N-wire is there and I can't see it? My network analyzer shows me the values ​​in the appendix. So it is displayed 230V against N in any case, but where from? It also shows me the voltages offset by 120 ° (against N!) And it also shows me phase against phase 400V. My measurement setup is also in the appendix. The manual of the network analyzer says, if it is a three-phase system, then you should put the last cable, which is actually intended for the N conductor, on phase 2 and use this as a reference potential and that's how I did it because simply none N-conductor can be seen! I'm pretty puzzled here and have to find a solution here. In the appendix you can also see exactly the 3 lines L1, L2 and L3. Each phase has 3 cables and according to the measuring device a current Inull is measured even though there is no N?

I would be very grateful for any suggested solutions

Best regards