The neutral wire is directly grounded at the end of the transformer, so it is connected to the ground wire.
The leakage circuit breaker is only connected to the live wire and the neutral wire. Its working principle is to measure the residual current, that is, under normal circumstances, all current flows from the live wire to the live wire. neutral wire. In simple terms, we can think of the amount entering from the live wire, from the output of the neutral line, the leakage current is zero.
In the event of a leak, part of the current flows from the electrical box to ground, the current in the live wire and neutral wire paths is unbalanced and the difference exceeds the set value (usually 30 mA for domestic use. ), the leakage switch will trip.
Neutral line (N): mainly used in the working circuit and leads to the main line from the neutral point du transformer to earth.
Earth wire (PE): Not used for working circuit, only used as protective wire. Using the absolute "0" voltage of the earth, when a leakage occurs in the equipment shell, the current will flow quickly into the earth, even if the PE line is open circuit, it will flow into the earth from the nearby earthing body. (After grounding the neutral point of the transformer, bring out the main line and repeat grounding every 20 to 30 meters).
Detailed information:
In the TN-S power supply system, the residential power loads are generally different, that is, the three-phase load is unbalanced and the three-phase transformer generally uses Y-YN0 wiring, the neutral points of the three-phase windings of the transformermator are connected together and grounded.
This line leads to the neutral line (N). The main part of the neutral line is also called the neutral line. The neutral line ensures that the voltage of each phase of the three-phase load is unbalanced. is equal to 220 V, so the neutral line, do not install fuses or switches.
These four three-phase wires (U, V, W, N) come from the electrical distribution room to the civil building. Under normal circumstances, each building should have an earthing device that meets national technical standards. standards. The wire removed from the grounding device is the ground wire (PE).
Generally on the first floor of the building, the ground wire and neutral wire of the electrical distribution room are connected together as one, and then divided into two parts to provide the neutral wire and ground wire . For each unit of the building, the objective is to bring up to daterepeatedly removes the neutral line (the main part of the neutral line), to improve the zero protection level of the system and reduce the risk of electric shock in the event of a fault.
According to national standards, the neutral wire has a blue sheath and the ground wire has a yellow-green sheath.
In summary, the neutral line is the line drawn from the neutral point of the transformer, and the ground wire is the line drawn from the grounding device of the building.
Under normal circumstances, the main part of the neutral line will pass a small unbalanced current, but the current through the neutral line of each phase is equal to the current through the live wire of that phase, and ground There is no current flowing in the wire, and the metal shell of the electrical equipment connected to the ground wire has no potential during normal operation. The neutral wire and the ground wire cannot be exchanged, such asIf the leakage protection switch is reversed, it will operate and cut off the power supply.
References:
References:
Can the ground wire and neutral wire of a three-phase motor be connected at the same time
< p>1. You Since it is a diesel generator, it must (usually) be used for its own independent power supply that is not connected to the power grid.2. According to electrical theory, if your generator's output voltage exceeds 36V, you need to install grounding protection. The main purpose is to protect personal safety in the event of a leak in the circuit. The switch protection function can be triggered immediately to avoidter injuries.
3. At the same time, it should be noted that the switch located at the appropriate position at or behind the generator output must have the necessary protective function to prevent it from tripping in the event of a problem!
No. When the neutral wire and ground wire are connected at the same time, if the motor high level switch has leakage protection, it will act incorrectly due to inaccurate detection of leakage protection and will not be able to provide accurate protection. . This is called “repeated grounding”.
The neutral line should not be grounded repeatedly. In fact, it is not allowed to be grounded repeatedly after the leak detection point.
You can refer to “Repeated Grounding” from Baidu Encyclopedia