Three-phase electricity is a three-phase four-wire system, that is, the three-phase four-wire "three lights and one zero" system, which can use 220V and 380V power supplies;
Three-phase alternating current is a type of electrical energy. The form of transmission is called three-phase electricity. Three-phase AC power is a power supply consisting of three AC potentials with the same frequency, amplitude and phase differences of 120° from each other. Three-phase alternating current has many uses. Most AC electrical equipment in industry, such as motors, uses three-phase AC, which is the often-mentioned three-phase, four-wire system. In daily life, single-phase power supply, also called lighting power, is mainly used. When lighting electricity is used for power supply, one of the electricited three-phase is used to power electrical equipment, such as household appliances, and the other line is the fourth line of the three-phase four-wire, which is the neutral line. . The neutral line is drawn from the neutral point of three-phase electricity.
Features:
A three-phase generator is called a three-phase power supply.
A circuit powered by a three-phase supply is called a; three-phase circuit;
The phase-neutral line is called phase voltage and the voltage is 220 V.
The colors of three-phase electricity are: Phase A is ** , phase B is green and phase C is red. Currently, there are several names: A, B, C or L1, L2,. L3 or U. V, W, the order is the same.
Principle:
The concept of "three-phase electricity" is: when the coil rotates in the magnetic field, the wire cuts the magnetic field lines to produce an electromotive force induced, andits pattern of change can be represented by a sinusoidal curve. If we take three coils and place them at a 120 degree angle from each other in space, the three coils will always rotate at the same speed in the magnetic field and three induced emfs of the same frequency will be induced. Since the spatial positions of the three coils differ by 120 degrees from each other, the generated current is also a three-phase sinusoidal change, called three-phase sinusoidal alternating current. Many places in industrial equipment use three-phase power, such as three-phase AC motors.
The voltage between two phases is 380 VAC and the voltage at any relative neutral point is 220 VAC. Divided into phase A, phase B and phase C. The lines are represented by L1, L2 and L3. (Three phase AC also has 660VAC and 6000VAC power supply due to different uses).
A generator capable of producing potentials with equal amplitudes, equal frequencies and a phase difference of 120° is called a three-phase generator; a three-phase generator is used as the power source, called a three-phase generator; three-phase power supply; a three-phase power supply The circuit which supplies the energy is called a three-phase circuit. U, V and W are called three phases. The voltage between the phases is the line voltage and the voltage is 380 V. The voltage between the phase and the neutral point is called phase voltage and the voltage is 220 V. The neutral wire is connected to the neutral point and to any live wire to supply current from the single-phase power supply.
Three-phase four-wire heater connection method
Misunderstand that 380V refers to line voltage and 220V refers to phase voltage.
In real 380V lines there is usually no n wireeutre, only phase wires and ground wires, and it is a three-phase four-wire system. If the equipment needs it, it can add a neutral line to the three-phase five-wire system.
There is therefore no single phase in the 380V line, at least two phases are used.
The two live wire and one neutral wire connection method you mentioned uses a 220 two phase line. If it is 380V there is no need for a wire neutral.
Basic knowledge: In the three-phase five-wire system, the voltage of each element on the neutral line is 220 V, called phase voltage, and the voltage between each of the two phases is 380 V , which is called line voltage.
The most obvious application of three-phase is the electric motor. Three-phase alternating current can easily change the direction of the motor.
The three-phase four-wire connection method of the heater is that the voltage between twolive wires is 380 volts, and the voltage between any live wire and the neutral wire can form 220 volts. The generator is three-phase and four-wire (three fires and one zero), and the distribution cabinet is three-phase and five-wire (three fires and one zero and one ground). After fire to fire and zero to zero, the ground wire of the distribution cabinet is directly connected to the ground wire.