Why the voltage between the two phase wires is 380V: First, let’s briefly talk about the line voltage and the phase voltage: the line voltage is the voltage between the live wire and the live wire, which is 380V, and the phase voltage is any one of the live wire and the middle of the three live wires. The voltage between the sex lines is 220V
The voltage is reduced by the transformer to satisfy our use. The secondary side of the transformer adopts the star connection method. There are three live wires respectively ABC three-phase, and work on the neutral point to connect to zero, leading to a neutral wire ；
We can clearly see from the voltage vector diagram that the line voltage is √3 times the phase voltage, and the voltage between any two phases of phase A, phase B and phase C from the secondary side of the transformer is 380V, so one of the two live wires The voltage between them is 380V;
In addition, the phase voltage is the voltage to ground of any one of the three phases of ABC, that is, the voltage to the working neutral line. This is the phase voltage. The relationship between it and the line voltage can be seen from the vector diagram as √3 times. That is, the line voltage is √3 times the phase voltage; so the phase voltage is equal to 380%√3=219.4, which is what we often call 220V;
Finally, let me tell you that 220V and 380V are what we often call them. In fact, the actual voltage fluctuates between the above two voltage values. The actual operation does not operate at the precise values of 220V and 380V.