Welcome: Hunan Intelligent Applications Tecgnology CO.,ltd.-HNIAT.com
Language: Chinese ∷  English

Basic knowledge

Basic knowledge of EMC theory-grounding design

Grounding is one of the important means to suppress electromagnetic interference and improve the electromagnetic compatibility of electronic equipment. Correct grounding can not only suppress the influence of interference, but also restrain the equipment from radiating interference; on the contrary, wrong grounding will introduce serious interference and even make electronic equipment unable to work normally.

1. The concept of grounding

"Earth" in electronic equipment usually has two meanings: one is "earth" and the other is "system reference ground". Grounding refers to the establishment of a low-resistance conductive path between a certain selected point of the system and a certain potential reference. "Connecting to the earth" is to use the earth's potential as the reference and the earth as the zero potential to connect the metal casings of electronic equipment and circuit selection points to the earth through a grounding device composed of grounding wires and grounding poles. "System reference ground" refers to the reference conductor of the signal circuit (electronic equipment usually uses metal base, casing, shielding or thick copper wire, copper tape as the reference conductor), and set the reference conductor potential to be relatively zero potential, but not The zero potential of the earth is referred to as the system ground for short. There are two purposes of grounding: one is for safety, called protective grounding. The metal shell of electronic equipment must be connected to the ground, so as to avoid the occurrence of excessively high ground voltage on the metal shell due to accidents and endanger the safety of operators and equipment. The second is to provide a low-impedance path for the current to return to its source.

2 Types of grounding

In fact, various ground wires are electrically or physically connected, and there is not necessarily a clear division. In the ground system, sometimes a ground assumes the role of both a protective ground and a mine-protection ground; or both a working place and a protective ground. And the ground connection of different functions is aimed at different electrical objects, and the focus of the processing method will be different.

a. Protective grounding

Protective grounding is to protect the safety of equipment, devices, circuits and personal safety, to prevent lightning strikes, static electricity from damaging the equipment, or to protect personal safety in the event of equipment failure. Therefore, protective grounding must be adopted in the chassis and metal chassis of equipment, devices, circuits.

The principle of protective ground protection is: by short-circuiting the equipment shell with fault voltage to the earth or ground terminal, the short-circuit current generated during the protection process disconnects the fuse or air switch, so as to protect the safety of equipment and personnel.

b. Working ground

The working ground is the equipotential reference point or reference plane of the signal between the single board, motherboard or system, which provides a low impedance channel for signal return. The signal quality largely depends on the quality of the working ground. Due to the characteristics of the grounding material and other technical factors, no matter how well the grounding conductor is connected or lapped, there will always be a certain impedance. The return of the signal will cause a voltage drop on the working ground wire and form a ground ripple. The signal quality has an impact; the weaker the signal, the higher the signal frequency, the more serious this impact. Nevertheless, it is still very important to minimize the impedance of the working grounding conductor in the design and construction.

CONTACT US

Contact: Manager Xu

Phone: 13907330718

Tel: 0731-22222718

Email: hniatcom@163.com

Add: Room 603, 6th Floor, Shifting Room, No. 2, Orbit Zhigu, No. 79 Liancheng Road, Shifeng District, Zhuzhou City, Hunan Province

Scan the qr codeClose
the qr code