 # What is three-phase alternating current? Phase voltage? Line voltage?

Thu Nov 29 14:42:38 CST 2018

The electricity used in our daily life is single-phase alternating current, and a power line consisting of a single line of fire and a neutral line is a single-phase alternating current. There is only one fire line, so it is called single-phase alternating current. It may not be necessary for me to say here. Since a single FireWire is called single-phase AC, then there must be three FireWires on the three-phase AC. This understanding is also correct because it does have three FireWires. It is also better to remember and understand.

The three-phase alternating current is composed of three alternating current circuits with the same frequency, equal potential amplitude, and 120 phase difference.

Power Systems.

Frequency: refers to the number of periodic changes completed per unit of time. It is the amount that describes the frequency of periodic movements. The common symbol is f or ν, and the unit is in fractions of a second. The unit is Hertz, which is abbreviated as “Hz” and the symbol is Hz. . This is a constant, as long as it is in China, whether single-phase or three-phase frequency is 50HZ. The red line from A to C in the figure above, and then B is a cycle, so the frequency can also be understood as completing 50 cycles per unit time.

What is the amplitude of the potential is very difficult to explain. You understand that the voltage at the highest point in the above diagram is equal and the voltage at the lowest point is also equal.

Phase difference: The difference between two alternating current phases with the same frequency. What is the difference between 120 degrees of phase difference? Look at the figure below. In the above figure, two or two alternating currents with the same frequency are not the 120 corners, that is, the six places where I draw red circles. So to meet the above three conditions, the three frequencies are the same, the potential amplitude is equal, and the phase difference is 120 degrees each other. In everyday life, the single-phase AC voltage is 220V, while the three-phase AC voltage is 380V, and the single-phase is 220V. So why is the three-phase voltage not 660V? This is because the voltage is divided into two types, one is the phase voltage, which is also called a FireWire. The voltage between the neutral line, so the voltage is 220V. The other type is the line voltage, which is the voltage between the two FireWire lines. Since it is two lines of fire, the voltage should be 440V. This involves the connection of three-phase alternating current, and finally it is derived through various formulas. That is, the line voltage is 1.732 times the phase voltage. That is 220 by 1.732 about 380, so the line voltage is only 380V. In the above figure, two or two alternating currents with the same frequency are not the 120 corners, that is, the six places where I draw red circles. So to meet the above three conditions, the three frequencies are the same, the potential amplitude is equal, and the phase difference is 120 degrees each other. In everyday life, the single-phase AC voltage is 220V, while the three-phase AC voltage is 380V, and the single-phase is 220V. So why is the three-phase voltage not 660V? This is because the voltage is divided into two types, one is the phase voltage, which is also called a FireWire. The voltage between the neutral line, so the voltage is 220V. The other type is the line voltage, which is the voltage between the two FireWire lines. Since it is two lines of fire, the voltage should be 440V. This involves the connection of three-phase alternating current, and finally it is derived through various formulas. That is, the line voltage is 1.732 times the phase voltage. That is 220 by 1.732 about 380, so the line voltage is only 380V.

In the above figure, two or two alternating currents with the same frequency are not the 120 corners, that is, the six places where I draw red circles. So to meet the above three conditions, the three frequencies are the same, the potential amplitude is equal, and the phase difference is 120 degrees each other.

In everyday life, the single-phase AC voltage is 220V, while the three-phase AC voltage is 380V, and the single-phase is 220V. So why is the three-phase voltage not 660V? This is because the voltage is divided into two types, one is the phase voltage, which is also called a FireWire. The voltage between the neutral line, so the voltage is 220V. The other type is the line voltage, which is the voltage between the two FireWire lines. Since it is two lines of fire, the voltage should be 440V. This involves the connection of three-phase alternating current, and finally it is derived through various formulas. That is, the line voltage is 1.732 times the phase voltage. That is 220 by 1.732 about 380, so the line voltage is only 380V.