However, in practical application, the neutral point (zero potential) will shift and the neutral line potential will no longer be zero because the three-phase lead-out load of the transformer cannot be absolutely balanced. At this time, the voltage between the neutral wire and the ground wire is not equal to 0. At present, the zero line of the user terminal is repeatedly grounded, so that the voltage between the zero line and the ground line is zero.
The generation of 0v voltage is relative, so we can regard 220V as a battery, with the positive electrode as the live wire and the negative electrode as the zero line. The negative electrode is in good contact with the earth, and so is the grounding wire (the earth is a good conductor).
Extended data:
Circuit difference
Neutral line (N): The main line which is mainly used in the working circuit and leads from the neutral point of the generator and transformer and is grounded.
Grounding wire (PE): it is not used for working loop, but only used as protection wire. Using the absolute "0" voltage of the earth, when the equipment shell leaks electricity, the current will flow into the earth quickly, even if the PE line is open, it will flow into the earth from the nearby grounding body. (After the neutral point of transformer is grounded, lead out the trunk line and repeat grounding every 20-30m).
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