Three-phase power supply: A three-phase AC power supply is composed of three AC potentials with the same frequency, equal amplitude, and a phase difference of 120 degrees from each other. It is generated by a three-phase AC generator. The single-phase AC power used in daily life is provided by one phase of three-phase AC power, and single-phase AC power generated by single-phase generators is rarely used.
The power generated by the generator is three-phase, and each phase and neutral point of the three-phase power supply can form a single-phase circuit to provide power energy for users. Simply put, three-phase electricity has three phase wires (live wire) and one neutral wire (or neutral wire), sometimes only three phase wires are used. According to Chinese standards, the voltage between phase lines is 380V AC, and the voltage between phase lines and zero lines is 220V AC. Single phase electricity has only one live wire and one neutral wire, and the voltage between them is 220 volts AC. Three phase alternating current is a combination of three sets of single-phase alternating currents with equal amplitude, frequency, and phase difference of 120 °. Single phase electricity is the combination of any phase line and zero line in three-phase electricity.
A three-phase circuit consists of three parts: a three-phase power supply, a three-phase load, and a three-phase transmission line. The advantages of a three-phase circuit are as follows:
1. In terms of power generation, it can increase power by 50% compared to a single power source; In terms of transmission: 25% less steel than single transmission;
2. In terms of distribution: three-phase transformers are more economical and convenient to connect to loads than single transformers;
3. Electrical equipment: simple structure, low cost, reliable operation, and convenient maintenance.