How to connect the grounding wire of the distribution cabinet and how to do the working grounding wi

1. Grounding requirements for the grounding wire of the distribution cabinet:

The power supply bureau inspects the grounding resistance standard for 4 or less, and good grounding installation: dig a trench more than 15 meters long and 70 cm deep, use galvanized meter triangle iron to lay a triangle iron per meter in the ditch, and then weld and connect it together with galvanized round iron.

Detect whether the installation of the ground wire is qualified should be 50 meters away from the installation of the ground wire with galvanized iron after 70cm, and the installation of the ground wire with a European mother meter measured resistance value below 4 is qualified, this ground wire can be used as the grounding of the distribution box.

Second, the distribution box grounding requirements:

1. The grounding "busbar" (grounding bar, PE bus) in the box is directly connected to the power ground wire or grounding system;

2. The metal box itself should be processed with a "box grounding bolt" (with PE logo), which must be connected with the grounded PE row with a copper core wire or a special braided soft wire;

3. The metal threading pipe connected with the box must also have a reliable electrical connection with the box (simple can be welded and connected with galvanized round steel and flat steel);

4. The part of the electrical parts in the box that must be grounded should also be connected with the PE row;

5. The ground wire in all the circuits that need to be allocated is led out by the PE row.

Only by correctly operating the grounding wire can the value of the grounding wire be brought into play, which is the basis of safety precautions.

If you are close, you can pull it out of the power distribution room, and if you are far away, you can hit an iron rod nearby and put it underground.

The total ground into the electrical box, "if the electrical box has two rows of terminals, you can use one to do the ground and one to do zero, if there is only one ground wire to tie up" The electrical box should also be grounded, and then to the branch line of the electrical appliance and the ground and the total ground of the electrical box are tied together! Industrial power distribution cabinets generally have grounding columns, just below the cabinet!

Three-phase four-wire system, in the low-voltage distribution network, the transmission line generally adopts the three-phase four-wire system, in which three lines represent A, B, C three-phase, and the other is the neutral line N (if the neutral point on the power side of the circuit is grounded, the neutral line is also called the neutral line (the old-fashioned name, should be gradually avoided, renamed PEN, if not grounded, then in the strict sense, the neutral line cannot be called the neutral line).

In the single-phase transmission line entering the user, there are two lines, one we call the phase line L, and the other we call the middle line N, the middle line normally passes the current to form the circuit of the current in the single-phase line.

In the three-phase system, when the three-phase is balanced, the neutral wire (neutral line) is current-free, so it is called the three-phase four-wire system; In the 380V low-voltage distribution network, the N-line is set up to obtain the 220V phase-to-phase voltage from the voltage between the 380V lines, and it can also be used for zero-sequence current detection in some occasions to monitor the balance of three-phase power supply.

Repeat grounding. Repeated grounding is a system in which the neutral point is directly grounded, and the grounding device is connected with a metal wire at one or more places of the zero trunk. In the low-voltage three-phase four-wire system neutral direct grounding line, the construction unit should ground the terminal of the zero trunk line and branch line of the distribution line during installation, and the zero trunk line should be grounded every 1 km. For distribution lines with a grounding point of more than 30 meters, the neutral line at the access user should still be repeatedly grounded.

All single-phase and three-phase electrical equipment with metal shells need to be protected and grounded.

Why is the ground wire electrified1, it may be that the earth is not equipotential, in this case, after the ground wire is connected to the earth, there is also a potential difference, which also leads to the ground wire being electrified. 2. There are high-frequency interference sources around the ground wire, which will also affect the normal operation of the ground wire, resulting in the ground wire being electrified. 3. In addition, near the PE line, there is a large current passing through, which leads to some stray current flowing to the PE line, resulting in the leakage of the ground wire.

4. If the N wire and the PE wire are shared, or the N wire and the PE wire are connected in reverse, it will also cause the ground wire to have electricity. 5. The electrical equipment used has the phenomenon of leakage, and the phase wire and ground wire are short-circuited. Or due to rainy weather, the circuit is short-circuited, and the wire will be electrified.

I can't connect! The grounding of the transformer is divided into two types, one is the grounding of the transformer shell, the other is the grounding of the neutral point of the transformer, and the latter is the starting point of the total zero line. Since the grounding is mainly used to protect the safety of the user side, the grounding of the transformer and the grounding of the distribution box cannot be connected together!

The reason is very simple, the general grounding standard for civil buildings is not more than 4 ohms, and if it is shared with the lightning protection connection of the building, it is not more than 1 ohm. At this time, if the phase wire of the power distribution equipment enters the ground through the shell, the shell will be live, and a closed power supply loop will be formed between the grounding resistance and the neutral point wiring resistance of the transformer through the ground, we know that the two resistors are connected in series, the current is equal, and the greater the resistance, the greater the voltage on it. The smaller the grounding resistance on the user side, the smaller the voltage that can ensure that the human body can contact the housing of the power supply equipment.

Of course, in today's civil building power supply protection is so perfect, the protection of equipment grounding will cause the circuit breaker to trip, or through the leakage protection switch, to protect personal safety.

But industrial buildings and temporary electrical power may not be so well protected, and if there is an extreme case of equipment failure, the size of the ground resistance is critical.

Generally speaking, the outdoor distribution trunk line is a three-phase four-wire system, and the distribution box should be grounded separately or repeatedly grounded. The user line after repeated grounding generally adopts the three-phase five-wire system, especially for the line after the installation of the total leakage protection switch.

In addition, there are different interpretations in different power supply systems. The TT system is different from the TN system, in the TN-C, TN-C-S system, the transformer grounding and the distribution box grounding wire must not be connected together.

In short, this is a highly normative issue, and professional matters should be handed over to professional people to deal with, and the specific situation should be analyzed on a case-by-case basis.

Connected square millimeters.

Copper wire. Because:

1. The ground connected to the cabinet body of the low-voltage control cabinet is a protective ground wire, not a working ground, and there is no need for a wire with too much pressure.

2. When the cabinet generally controls the load is not very much, the square copper wire is sufficient.

3. The cabinet bears a large load according to the national standard (GB7251): grounding wire.

The minimum cross-sectional area of copper wire is not less than 10 square millimeters, and the aluminum wire is not less than 16 square millimeters.

Each active part is connected to one, and each one is generally not less than 16 square bare copper braided grounding belts.

Make sure all equipment in the electrical control cabinet is well grounded, using short and thick ground wires to connect to a common grounding point or on a grounding busbar. Any control device connected to the inverter (e.g. a PLC) should be co-grounded with it and should also be grounded with short and thick wires. Flat conductors, such as metal mesh, are preferable because they have a low impedance at high frequencies.

The grounding wire is a wire that directly connects to the earth, which can also be called a safety route, and when it is dangerous, it directly transfers the high voltage to the earth, which is a lifeline.

Due to the poor insulation performance of household appliances or the humid use environment, the shell of the household appliances will have a certain amount of static electricity, and in serious cases, electric shock accidents will occur. In order to avoid accidents, a wire can be connected to the metal shell of the electrical appliance, and the other end of the wire is connected to the ground, and the grounding wire will bring static electricity into the ground and release it once the electrical leakage occurs. In addition, it is more important for electrical maintenance personnel to use the soldering iron to solder the circuit, sometimes because the electric soldering iron is charged and the integrated circuit in the electrical appliance is damaged.

Friends who use computers sometimes ignore the grounding of the main chassis, in fact, the grounding of the main chassis of the computer can prevent the occurrence of crashes to a certain extent.

Grounding wires in the power system: It is an important tool to ensure that workers are required in the event of an unexpected voltage on equipment and lines that have been powered out. According to the ministry, the grounding wire must be made of bare copper flexible wire of more than 25mm2.

Summary. We are happy to serve you and help you solve your problems in May. I wish you a happy According to the general provisions: the cross-sectional area of the main mother of the substation is greater than or equal to 2 times the zero cross-sectional area.

Don't care about the section of the busbar, the main busbar is arranged in phase order from the upper part of the cabinet through each cabinet, the equal section of the zero row and the ground row can be passed through the lower part of the cabinet laterally, the insulator is installed in the middle, and the end is connected when the ground is repeated. It is recommended that the zero row and the ground row are made of 80*8 of the same material.

Question: How to ground the grounding busbar of the low-voltage distribution cabinet?

We are happy to serve you and help you solve your problems in May. I wish you a happy According to the general provisions: the cross-sectional area of the main mother of the substation is greater than or equal to 2 times the zero cross-sectional area.

Don't care about the section of the busbar, the main busbar is arranged in phase order from the upper part of the cabinet through each cabinet, the equal section of the zero row and the ground row can be passed through the lower part of the cabinet laterally, the insulator is installed in the middle, and the end is connected when the ground is repeated. It is recommended that the zero row and the ground row are made of 80*8 of the same material.

Where is the grounding copper bar connected?

On the ground. How to connect the grounding row in the distribution cabinet.

The standard for the inspection of grounding resistance by the power supply bureau is 4?Below, good grounding installation: dig a trench more than 15 meters long and 70 cm deep, use galvanized rice triangle iron to lay a triangle iron per meter in the ditch, and then weld all the galvanized round iron together.

To detect whether the installation ground wire is qualified, it should be 50 meters away from the installation ground wire and then use galvanized iron to cut 70cm, and the resistance value of the installation ground wire should be measured with a European female meter at 4?The following is qualified, and this ground wire can be used as the grounding of the distribution box.

1. The grounding "busbar" (grounding bar, PE bus) in the box is directly connected to the power ground wire or grounding system; 2. The metal box itself should be processed with a "box grounding bolt" (with PE logo), which must be connected with the grounded PE row with a copper core wire or a special braided soft wire; 3. The metal threading pipe connected with the box must also have a reliable electrical connection with the box (simple can be welded and connected with galvanized round steel and flat steel); 4. The part of the electrical parts in the box that must be grounded should also be connected with the PE row; 5. The ground wire in all the circuits that need to be allocated is led out by the PE row.

Can the ground wire of the transformer be connected to the ground row?

Friend, I sent it, can you read it carefully?

In a home distribution box, there are generally three wires, which are the live wire (usually red or brown), the neutral wire (usually blue or black), and the wireGround wire (usually green or yellow-green).。The function of the grounding wire is to ensure the safe use of electrical equipment, if the equipment leakage, the current will flow back to the ground through the grounding wire, reducing the harm to the human body.

The grounding wire needs to be connected to a special grounding pole or grounding coil, and at the same time, it is necessary to ensure that the grounding wire can be stably connected to the ground. Once the ground wire is connected, you can use a multimeter or test pen to check if the ground wire is connected. For safety reasons, the joints of the grounding wire should be tightly fastened and should not be loose.

If you are not familiar with the connection and grounding wire of the circuit, it is recommended to find a professional electrician for installation and maintenance.

The ground wire is marked with a yellow-green line, but the yellow-green line in the figure is used as a neutral line.

The zero line is marked in blue, and it is not clear from the diagram why the ground and zero lines are not in normal use.

Generally, the household distribution box should be made a ground wire row, and the total ground wire of the household and the various wires of the sub-circuit can be pressed to the ground wire row.

In general, for home distribution boxes, the ground wire is usually a yellow-green wire, also known as a PE wire. Before connecting the ground wire, you must first disconnect the power supply and then connect the ground wire to the ground wire of the building to ensure that the connection is secure. When wiring, the insulation layer on the terminal should be removed, and then the end of the ground wire should be neatly arranged on the terminal and fastened with screws.

Because standards and regulations vary from region to region and country, be sure to follow local industry standards and regulations when wiring. If you don't understand the wiring method or face any difficulties, it's best to ask a professional electrician to help.

Because the line is not installed with a standard layout (color), it is difficult to say, and it must be tested by a multimeter to judge.