What are the common misunderstandings of grounding technology?

The connection between the classification of grounding

In a building, the best way to ground is to establish three separate grounding systems. The first type is lightning protection grounding, which is a protective ring around the building connected to the grounding rod. This protection ring is also used as the terminal of the lightning rod feeder. The second type is the grounding of the power supply system. This system is entering the building. At the entrance to the ground, it is safe and reliable to ground. Most related specifications require that the grounding impedance should not exceed 3 ohms.

A third type of grounding system—a signal loop or instrument grounding—in the building where sensitive electronic equipment, communications equipment, computer systems, and control systems are used. This separate instrument grounding facility should be individually connected to a dedicated instrument grounding grid with a ground impedance of no more than 3 ohms as the reference electrical plane for the signal loop of the electronics. It is often difficult to separate the ground of the power supply system from the ground of the instrument or electronic equipment. Separation depends on the structure of the device, the isolation of the instrument or electronic device from its casing and other wires connected to the safety fuse. Sometimes the separation of the signal loop ground and the power system ground can be achieved by using an RF choke in the safety ground loop. It can also be implemented using a delta-Y power conversion device and a specific area that is allowed by the safety regulations to rebuild a safety grounding facility. It is important to prioritize safety standards in the equipment area and any design should strictly adhere to safety technical requirements and standards.

In the past, people have misunderstandings about grounding.

In the past projects, people have misunderstandings and deficiencies in the grounding technology. It is often simple to assume that the role of grounding is nothing but lightning protection and ensuring the safe operation of the power system, providing circuits to the circuit. Think of the earth as a large filter, and everything will be fine when the equipment is grounded. Every engineering and technical personnel engaged in electric power, electrical appliances and electronics will deal with grounding all day. If you ask a technician: Do you know the grounding technology? He may think that the grounding technique is pediatrics. Sneak a question to your question. If you ask again: What is the characteristic frequency? What is the critical length of the grounding pole? I am afraid most engineers and technicians can't answer.

Electromagnetic interference is often related to grounding technology

In recent years, from the construction and operation of leading organizations at all levels and large domestic enterprises, the author has learned that this inconspicuous "pediatrics" has become a difficult department. The grounding technology has become abstract. Through repeated research and digestion on various materials related to grounding technology obtained in the past few years, it was found that filters for suppressing common mode and differential mode conducted interference in power supply lines and shielding measures for preventing radiation interference are closely connected with grounding technology.

Some large state-owned enterprises have introduced a whole set of production lines, and the products produced have become the country's fist products, creating huge wealth for the country. It is these international production lines that also frequently cause electromagnetic interference, which affects safe production. In the past few years, foreign manufacturers have come to dozens of people to hundreds of electromagnetic compatibility experts to carry out the inspection of the equipment. Some experts have turned all the equipment wiring several times.

Some hospitals use electric knives that occasionally cause burn patients. In fact, these equipments are very sophisticated and the safety measures are very strict. How can these accidents occur?

How to solve the electromagnetic interference problem

What's more important is that such an abnormal phenomenon often fails to find the cause, or where the root of the problem can't be found. It is just a headache and a painful foot. What equipment was damaged and what equipment was replaced. Who knows when the next interference will come out... I don’t dare to say that these problems are caused by grounding technology. Because electromagnetic compatibility is more complicated, it can be said that grounding technology plays an important role in electromagnetic compatibility.

Is the problem of electromagnetic interference a syndrome? Not also! The author is ignorant, everything has its own internal laws. The reason why the interference problem is not available for a long time is to explain our lack of knowledge in this subject area. As long as we have a strong professional knowledge, especially the wave theory, and find out the transmission laws and characteristics of electromagnetic interference in these buildings, the problem can be solved.