Can you distinguish between phase wire, live wire and neutral wire?

In any circuit, when the circuit is not in operation, the line with voltage (commonly known as a charged line) is called the phase line, and the line without voltage is called the neutral line.

In a single-phase circuit, to make it more vivid and easier to understand, the phase line and the neutral line are respectively given two alternative names, namely the live wire and the neutral wire. Therefore, the phase line = the live line, and the neutral line = the neutral line.

In any circuit, when the circuit is not in operation, the line with voltage (commonly known as a charged line) is called the phase line, and the line without voltage is called the neutral line.

In a single-phase circuit, to make it more vivid and easier to understand, the phase line and the neutral line are respectively given two alternative names, namely the live wire and the neutral wire. Therefore, the phase line = the live line, and the neutral line = the neutral line. The phase line is easy to understand. The output of electrical energy from a power plant relies on the phase line. In a three-phase circuit, the Angle between the three phase lines is 120°, and the voltage between the three phase lines is 380V. They have a common intersection point, which is called the "neutral point". The voltage between the neutral point and any phase line is 220V (calculated by trigonometric functions). The line drawn from the neutral point is called the "neutral line".

Therefore, for electrical appliances with a rated voltage of 380V, three phase lines are used. For electrical appliances with a rated voltage of 220V, use a single phase wire.

Here comes a problem. The circuit needs to form a complete loop to be used normally. Therefore, in a single-phase circuit that uses only one phase wire, a neutral wire is essential for it to function properly. In a three-phase circuit that uses three phase wires, electrical appliances can operate normally without the need for a neutral wire.

At this point, a question arises - if the voltage between the two phase lines is 380V, then why use three phase lines simultaneously?

This is because the voltage is only 380V when the Angle between the two phase lines is 120°. If the Angle between these two phase lines changes, the voltage will change accordingly. If three phase lines are used, the structure between them will be much more stable (the stability of a triangle).

Therefore, although two phase lines can also enable an appliance with a rated voltage of 380V to operate normally, they are usually not used in this way.

Both the neutral wire and the ground wire need to be grounded

The claim that the neutral wire (zero wire) is grounded is actually incorrect. The accurate statement should be that the neutral point is grounded.

The way of grounding

Whether it is the neutral point or the ground wire, their grounding methods are the same.

There are many grounding methods. The most common one is to weld flat steel into an "I" shape and bury it in a pit 1 meter deep. Sprinkle salt water into the pit again, and then weld a vertical flat steel on the flat steel inside the pit, extending it above the ground. This flat steel is connected to the ground wire or neutral point to complete the grounding.

The difference between the neutral wire and the ground wire

Since both need to be grounded, what are the differences between them?

The structure of the ground wire is relatively simple. One end is connected to the grounding device and the other end is connected to the user. Its function is relatively simple, which is to prevent the casing of electrical appliances from becoming electrified. Once an electrical appliance leaks electricity, the current on its casing will flow to the ground through the ground wire, thereby reducing the harm to the human body.

The neutral line belongs to the working line, and the current can pass through the neutral line and directly return to the power plant. It also has the following functions ↓

The function of neutral point grounding

Once a phase line is grounded (such as coming into contact with the ground due to leakage), a large short-circuit current will be generated as the neutral line is connected to the ground, prompting protective devices (fuses, circuit breakers, etc.) to quickly cut off the circuit to prevent more serious accidents.

At the same time, after the neutral point is grounded, it can ensure that the potential on the neutral line is the same as that of the earth, locking the neutral point at zero potential. This will prevent the neutral point from shifting, the Angle between phase lines from changing, and the three-phase voltage from being unbalanced.