What does the wire color represent
General regulations: The colors of the three-phase wires are yellow, green, and red, respectively A, B, and C three-phase. Blue represents the zero line, and yellow green is the grounding wire. When wiring, yellow, green, and red are connected to the live wire, blue is connected to the zero line, and yellow green is connected to the PE protection wire or the equipment shell (the outer shell is already connected to the grounding grid). Sometimes, when the color difference between the four lines is not very clear, the three lines with the same cross-section are the live line, and the ones with a slightly smaller cross-section are the zero line. The transformer you mentioned may be the power supply for the control circuit, such as 380V, connected to any two live wires; If it is 220V, connect one live wire and one neutral wire.
Practical operation: The safety factor is that red represents the live wire, blue represents the zero wire, and yellow or yellow white alternating lines represent the ground wire. The phase line is generally yellow, green, and red, the protective neutral line (PEN line) is black, and the protective line (PE line) is a yellow green dual color line. The protective line is strictly prohibited from being used as a phase line under any circumstances.
根据《住宅装饰装修工程施工规范》GB 50327-2001 16.1.4条规定：
According to Article 16.1.4 of the "Construction Code for Residential Decoration Engineering" GB 50327-2001:
“配线时，相线与零线的颜色应不同型槽模具 一次性止血带 保定水处理设备 一次性止血带 保定空压机 北京真空泵
When wiring, the color of the phase line and the neutral line should be different; the color of the phase line (L) in the same residential area should be unified, the neutral line (N) should be blue, and the protective line (PE) must be yellow and green