How does a three-phase network work?

Question

Physics

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Three-phase generator, three coils (or more), star connected, three-phase step-up and step-down transformer (if any), transmission line, neutral wire between neutrals to balance the voltage on the phases if the loads are not the same . It seems that this is more or less clear in the textbook on toe napsano.

Why earth the neutrals of the transformers (well, if there are any) and the neutral of the generator? Why not just use 4 wires? After all, then the potential difference between any phase wire and the Earth would be equal to zero, which means that no current would flow through a person who touched the Earth and the phase.

Do I understand the essence correctly: when the neutral breaks, the voltage will be skewed and everything that was calculated strictly to work with 220 V will die. To avoid this, grounding is done so that the Earth works like a wire, albeit not very good. But because of grounding, a person has the opportunity to become a light bulb between the ground and the phase wire, and now we have to think about protecting a person.

Answer 1

Why earth the neutrals of the transformers (well, if there are any) and the neutral of the generator? Why not just use 4 wires?

Savings on the neutral wire (one of the main advantages of a three-phase network in general is savings on wires).

After all, then between any phase wire and the Earth, the potential difference would be equal to zero

Why all of a sudden?? Here, even mathematics does not beat: let's even assume that the potential difference between the first phase and the ground is zero, but between the first and second - 380 V of the effective alternating voltage, which means that between the second and the ground is the same.