Can 380V and 220V neutral wires from different power sources be interchangeable
Safety regulations for low-voltage electrical installation; In order to prevent circulating currents caused by two different power sources from causing power supply and distribution accidents, users who use two power sources (including external and internal power sources) for power distribution must install a four pole dual throw switch to convert power distribution.
Two different transformer low-voltage power supply systems (i.e. A transformer low-voltage power supply system and B transformer low-voltage power supply system). Explain why a common zero line cannot be used.
The low-voltage winding coils of transformers are all connected in a Y-shape, and the working neutral wire is a wire named N wire that is connected from the middle common point O of the star shaped Y-point. Its main function is to provide 220V voltage for phase lines L1 → N, L2 → N, and L3 → N, respectively, for use by single-phase loads.
Simply put, when a single-phase load is operating, the phase line and the neutral line must form a loop to function properly.
Perhaps some skilled and bold individuals have said that I once tested the phase line of one transformer with the zero line of another transformer, using a 220V light bulb 💡 It just lit up. Here I will tell you that it is indeed possible to light up the light bulb, which is a working circuit formed by the resistance of the ground and the repeated grounding and protective grounding PE of another transformer.
For transformers installed in different locations, the protective grounding laid between them is tailored to local conditions and connected to the ground. The grounding resistance value is particularly affected by distance and soil humidity. Even if the grounding resistance value of each grounding device is within the normal range of R ≤ 4 Ω, there will be a 4 Ω+4 Ω+earth fault resistance R between them. Such resistance values are uncertain and are not suitable for conducting current, and the voltage within the normal working range of the load cannot be guaranteed.
To put it bluntly, this approach is particularly unsafe. The safety regulations for power supply systems are absolutely unacceptable. For circuits with residual current protectors installed in low-voltage power supply systems, they will immediately trip and stop power supply.
