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

In any circuit, when the circuit is not working, the line with voltage (commonly known as live) on the line is called the phase line, and the line without voltage on the line is called the neutral line.

In a single-phase circuit, in order to be more vivid and understandable, two aliases are given to the phase line and the neutral line, called live line and neutral line. Therefore, Phase = Live and Neutral = Neutral.

The phase wire is easy to understand. When the power plant comes out, the power output depends on the phase wire. 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 "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 "neutral line".

Therefore, an electrical appliance with a rated voltage of 380V uses three phase wires; an electrical appliance with a rated voltage of 220V uses one phase wire.

There is a problem here, the circuit needs to form a complete ring before it can be used normally. Therefore, in a single-phase circuit using only one phase wire, a neutral wire is necessary for proper operation. In a three-phase circuit using three phase wires, there is no need to use a neutral wire to make electrical appliances work normally.

At this point, a question arises—since the voltage between the two phase wires is 380V, why use three phase wires at the same time?

This is because the voltage between the two phase lines is 380V only when the angle between them is 120°. And if the angle between the two phase wires changes, the voltage will change accordingly. Whereas if three phase conductors are used, the structure between them is much more stable (triangular stability).

So while two phase wires will work for an appliance rated at 380V, it's not usually used that way.

Both neutral and ground wires need to be grounded

The neutral line (neutral line) is grounded, which is actually wrong. The accurate statement should be the neutral point grounding.

way of grounding

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

There are many ways of grounding, the most common one is to weld flat steel into an "I" shape and bury it in a pit 1m deep. Sprinkle salt water into the pit again, then weld a vertical flat steel on the flat steel in the pit, stretch out the ground. This flat bar is connected to the ground or neutral to complete the ground.

The difference between neutral and ground

Since both require grounding, what is the difference 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, it is to prevent the shell of the electrical appliance from being electrified. Once electrical leakage occurs, the current on the casing will flow to the earth 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 return directly to the power plant. At the same time, it also has the following functions ↓

The role of neutral point grounding

Once the phase line is grounded (accidents such as contact with the earth after leakage), a large short-circuit current will be generated due to the connection between the neutral line and the earth, prompting the protection device (fuse, circuit breaker, etc.) to quickly cut off the circuit to avoid more serious accidents produce.
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, and the neutral point is locked at zero potential. In this way, the neutral point shift will be avoided, the angle between the phase lines will be changed, and the three-phase voltage will be unbalanced.