PART.01 What is grounding?

As we all know, lightning will generate instantaneous high voltage and strong current. Once it hits the equipment on the ground without lightning protection measures, it will inevitably cause major damage. Therefore,  communication equipment with a large number of semiconductor de vices must be well protected against lightning.

Communication equipment usually uses the method of "equipotential bonding" to protect against lightning. The so-called "equal potential bonding" is commonly called "grounding", and "grounding" means connecting the device to the earth.

By grounding the lightning protection of the equipment, the lightning can be released to the ground before the lightning enters the equipment, so as to achieve the purpose of lightning protection.

In addition to lightning protection grounding for communication equipment, there are several other grounding methods, which will be introduced in detail below.

What are the types of PART.02 grounding?

There are three main types of grounding in communication equipment: lightning protection grounding, working grounding, and protective grounding.

Lightning protection grounding: refers to a method of connecting input or output power cables to the ground through a lightning arrester. The lightning arrester is actually a varistor, which will instantly pass through and become a conductor under high voltage. Therefore, by installing the lightning arrester in the input/output line of the equipment and connecting it to the ground wire, it can be effectively protected against lightning.

Working grounding: refers to a kind of grounding to ensure that the power system and electrical equipment meet the normal working requirements. Positive grounding is used in DC power communication equipment.

Protective grounding: The metal shell of electrical equipment may be charged due to insulation damage. In order to prevent such voltage from endangering personal safety, the metal shell of the equipment needs to be grounded. This kind of grounding is called protective grounding.

In life, grounding devices are also used in many places, such as large household appliances, such as refrigerators, air conditioners, etc., and the wires and plugs used are all three-core. Under normal circumstances, general electric appliances can work as long as there are two neutral wires and live wires. The three-core power cord like this one is used for grounding, that is, the grounding wire. According to the common sense of electricity use, the left neutral wire, the right hot wire, and the middle wire are generally used to distinguish.

In addition to daily life, grounding also plays an important role in communication bureaus (stations). It is not only related to the safety of equipment and maintenance personnel, but also directly affects the quality of communication.

With the maturity of lightning protection and grounding technology, people gradually realize that lightning protection and grounding are a systematic project, so how can better and effective lightning protection be achieved?

Thus, joint grounding was born~

PART.03 What is joint grounding?

Combined grounding is to connect the basic grounding body of each building in the communication bureau (station) with other special grounding bodies to form a common grounding network, and share a group of lightning protection grounding, working grounding and protective grounding of electrical equipment. The grounding method of the grounding system.

As shown in the figure below, when a strong lightning current flows into the ground, the potential of the ground rises immediately. Because all the ground wires are connected together, the ground potential of the communication equipment rises with the ground, and there is no potential difference between the ground and the ground. , will not damage the equipment due to lightning counterattack.

The joint ground in the figure below connects the working ground, lightning protection ground and protection ground together, and -48 V DC is a DC power supply.

It should be noted that the connection bodies of the joint grounding grid should be distributed in a network shape, and it is best to form a three-dimensional network, so as to have the functions of voltage equalization and equipotentiality. The grounding body must be made into a good equipotential body. The lightning protection grounding bar, protective grounding bar, and working grounding bar can be connected to the grounding body at different points according to requirements to meet the requirements of joint grounding.

PART.04 Combined grounding system application

As shown in the figure below, this is a joint grounding scheme for a certain computer room. In order to form an equipotential surface in the computer room on the same floor, special grounding bars are arranged around each floor to connect with the power supply equipment shell on the same floor, which is beneficial Lightning overvoltage protection to protect the safety of personnel and equipment.

This is the end of the introduction of the joint grounding system. Finally, the document gentleman will summarize the advantages of the joint grounding system~~~

PART.05 Combined Grounding System Advantages

• Eliminating the potential difference that endangers the equipment can make the potential between the wiring systems on the same floor roughly equal to the potential between the earth. The common ground busbar (the connection line that connects the current or voltage to the ground grid, or the conductor that connects the ground electrodes into one body) establishes a reference zero potential point for the whole world. When a ground potential rise occurs, the ground potential everywhere rises at the same time, and there is basically no potential difference at any time.
• Interference with the ground system is eliminated. Usually, a variety of ground wire systems are designed according to various electrical characteristics, and there is mutual influence among them. Now, after adopting a joint ground system, the ground wire system can achieve no interference.
• Good electromagnetic compatibility. Because the strong, high-frequency and low-frequency electricity are all at the same potential, and methods such as separate shielding equipment and branch ground wires are used, the electromagnetic compatibility performance is improved.