Paul or David
It would appear from your diagrams that the neutral conductor of the utility supply is grounded only at the transformer rather than being earthed at the customer service equipment in three of those systems. The PME system looks a lot like the normal practice here with the neutral conductor bonded to earth at the service disconnecting means. The system that you call PME has come under some criticism here because of the unknown effect of stray currents on human and domestic animal health. There is growing evidence that the stray currents have many negative effects on farm and ranch live stock.
Is the third system with RCD protection very common? It would appear that it keeps the neutral aloof from earth at all points on the customer premises.
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Tom
