In a TN-S system and for a configuration below (single-phase isolation transformer, rectifier and single-phase DC/AC converter) what should be earthed (connected to PE wire)?
I've been going through various sources and there are different views. In Ref1 it says that isolation transformer output is floating and should be referenced (grounded). Same as in Ref4, page 20 where neutral-ground bond is mentioned. However, Ref2 says in case of fault, "current path is contained within the secondary of the transformer, the RCD will not detect an imbalance and will therefore not trip. The operator is now in an unsafe environment with the potential for an electric shock as they may become the lowest point of resistance for the leakage current". Finally, Ref3 says "the inverters generate a neutral wire that is grounded in the auxiliary power supply", i.e. inverter output terminal 4 should be grounded. Not sure if this implies grounding rectifier terminal 4 as well. This reference is for rolling stock applications, so there might be some different general requirements. I could not find any recommendations on what to do when the inverter is supplying load (i.e. off-grid application).
Since the system is TN-S, neutral has been referenced to the ground at the source before entering the main panel. Do I need to re-reference neutral at every output terminal (transformer N, rectifier 4 and inverter 4)?
I guess, if there is a 400 V input, then it would make sense to reference inverter's output and create a TN-C system (Ref4, page 20).