1. http://baike.baidu.com/view/30130.htm
Three-phase transformers, there are many types, including three-phase three-winding transformers, three-phase single-phase transformers. winding transformers and self-coupling change, split change, etc. A three-phase common three-winding transformer has windings on the primary and secondary sides of each phase.
2. "According to the schematic diagram in the book, the two output wires of the step-down transformer are the same." There is only one output wire for each phase of the transformer, and there is. three output wires for the three-phase transformer.
3. “But why are there differences between the neutral wire and the live wire?” - The difference between the neutral wire and the live wire is only distinguishable on the bus bar. The transformer itself is not divided into neutral and wire. live wire. Power Transformer GenAlso, it is located on the busbar corresponding to a certain section of the electrical network. For the user side busbar, especially the 380V busbar, a three-phase four-wire system is generally used. A, B, C three phases plus a neutral wire, a total of four wires. The neutral wire is The potential connected to ground is zero, so it has five voltages. This is mainly due to the consideration of 220 V civil electricity and the safety of bus operation. The corresponding work of each phase and neutral line constitutes our 220V civil electricity, also called phase voltage. For three-phase motors, the phase-to-phase voltage is taken, for example 380 V. Three-phase motors usually also have a neutral line, which is connected to the neutral line of the busbar for protection against short circuits and other faults.