What is three phase alternating current What is three phase electricity?

A power supply consisting of three alternating currents with the same frequency, equal amplitude, and 120° phase difference from each other.

Three-phase alternating current has many advantages over single-phase alternating current, and it has obvious advantages in power generation, transmission and distribution, and conversion of electrical energy into mechanical energy. For example, the manufacture of three-phase generators and transformers is less material-saving than the manufacture of single-phase generators and transformers, and the structure is simple and the performance is excellent.

For another example, a three-phase motor made of the same material has a capacity 50% larger than that of a single-phase motor; In the case of transmitting the same power, the three-phase transmission line can save 25% of non-ferrous metals compared with the single-phase transmission line, and the power loss is less than that of the single-phase transmission. Due to the above-mentioned advantages of three-phase alternating current, it has been widely used.

Three-phase alternating current.

Generally, household electricity is single-phase alternating current, but the large-scale production and distribution of electric current, as well as most industrial electricity, are in the form of three-phase alternating current circuits. A high-voltage transmission line, usually four wires (called three-phase four-wire, one of which is the middle line). In essence, it is an alternating current with three wires carrying the same load strength and the same frequency, but with a phase difference of 120° between each other.

So the curve representing the voltage change of the three wires is a sine wave of the same frequency, and the bits are staggered by one-third of a period. The voltage to the ground wire for each of these three wires is called the "phase voltage", which is represented by R, S, and T. The voltage between each two wires in the three wires is called the "line voltage" and is represented by s t, t r and r s.

The change of phase voltage and line voltage to time is expressed as a sinusoidal curve, and the relationship between the peak value and the RMS value is exactly the same as that of single-phase alternating current, that is, the height above the zero line to the two horizontal thin lines represents the RMS values of the phase voltage and the line voltage uf and ul. The relationship between them is that the voltage value of the three-phase transmission line often refers to the effective value of the line voltage. The main advantage of the three-phase system is that the construction of the three-phase motor is simple and robust.

This electric motor is used as mechanical power all over the world.

Three-phase alternating current, generally 380 220V in China, where the voltage (line voltage) between the phase and the phase is 380V, and the voltage (phase voltage) between the phase line and the neutral line is 220V

The power system of AC circuit with the same frequency, equal potential amplitude and 120° phase difference is called three-phase alternating current.

Three-phase electricity is three-phase alternating current.

The abbreviation, also called power electricity, is three live wires and one neutral wire, also called three-phase four-wire.

The voltage between the neutral wire and each live wire is 220 volts, while the voltage between every two live wires is 380 volts.

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Three-phase alternating current is composed of three single-phase alternating currents with the same frequency and voltage, and the phase difference between them is 120°. This is like the line from the midpoint of an equilateral triangle to the three vertex corners.

Advantages of three-phase alternating current: (1) The manufacture of three-phase generators and transformers is more material-saving than the manufacture of single-phase generators and transformers, and the structure is simple and the performance is excellent. (2) The capacity of the three-phase motor made of the same material is 50 larger than that of the single-phase motor.

3) Transmit the same electric energy, compared with single-phase transmission line, three-phase transmission line can save non-ferrous metals 25, and the power loss is less than that of single-phase transmission. Therefore, the power generation and transmission of power plants are three-phase alternating current. High-voltage transmission lines are usually not connected to the neutral line (three-phase three-wire system), and the grounding wire is added at the secondary end of the low-voltage transformer as the neutral line (three-phase four-wire system).

Three-phase alternating current is a form of transmission of electrical energy, referred to as three-phase electricity. Three-phase AC power supply is a power supply composed of three alternating currents with the same frequency, equal amplitude, and 120° difference in phase.

Three-phase alternating current has many uses, and most of the alternating current electrical equipment in the industry, such as motors, use three-phase alternating current, which is often referred to as the three-phase four-wire system. In daily life, single-phase power supply, also known as lighting electricity, is mostly used. When lighting electricity is used, one of the three phases is used to supply power to the consumer, such as household appliances, and the other wire is the fourth wire in the three-phase four-wire, that is, the neutral line, which leads from the neutral point of the three-phase electricity.

The voltage of three-phase electricity is 380V, which is suitable for industrial electricity with relatively large power. For the user's electricity, take one of the live wires and the common neutral line to form a single-phase line, and the voltage is what we usually call 220V. For some electrical appliances with relatively large power, the normal household voltage cannot be brought up, so there will be three-phase electricity.

First of all, a conceptual mistake is that the triangle plug is not three-phase electricity, which is commonly known as power electricity, which refers to the type of 380V industrial electricity. The two-phase electricity is 220V, which is the type of civil electricity. (The three-phase and two-phase here cannot be judged by the number of plug pins alone.)

2。The plugs in the use of three-phase electricity are available with 4 pin and 5 pin plugs

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Three-phase alternating current is characterized by the saving of wires in power transmission and the generation of rotating magnetic fields.

Three-phase alternating current is generated by three sets of symmetrical windings of a three-phase generator, and each winding together with its external circuit is called a phase, which is recorded as a, b, and c respectively. Their combination is called three-phase system, and they are often supplied with three-phase three-wire system and three-phase four-wire system, that is, triangular connection and star connection.

The main advantages of the three-phase system are: saving wires in power transmission; It can generate a rotating magnetic field, and creates conditions for the development and application of asynchronous motors with simple structure and convenient use. The three-phase system does not exclude the supply of power to single-phase loads.

Therefore, three-phase alternating current has gained the most widespread application.

Three-phase alternating current is a power system composed of three alternating current circuits with the same frequency, equal potential amplitude, and 120° angle of phase difference. At present, China's production and distribution are three-phase alternating current.

Three-phase alternating current is a combination of three symmetrical sinusoidal alternating currents with a phase difference of 120 degrees. It is produced by the three symmetrical windings of a three-phase generator. Each winding and its external circuitry are called phase A and are recorded as A, B, and C, respectively.

The combination of its bands is called a three-phase system. They are usually powered by three-phase three-wire and three-phase four-wire systems, i.e., triangular connections and star connections.

Reasons: 1. In order to generate a rotating magnetic field without the use of auxiliary equipment Huifeng, at least three-phase power supply must be provided.

Three-phase alternating current can produce a rotating magnetic field in the stator windings of an AC motor, and this magnetic field is stable with a rotating magnetic field with a fixed direction of rotation.

2. The three-phase power supply system has many advantages.

In terms of power generation, the three-phase generator of the same size makes the power of the motor before the single-phase engine is larger, and the generator torque is constant under the same three-phase load, which is conducive to the work of the generator; In terms of transmission, the three-phase system saves transmission lines compared with the single-phase system, and the three-phase transformer is more economical than the single-phase transformer; In terms of electricity, three-phase electricity is easy to generate a rotating magnetic field to make the three-phase motor rotate smoothly.