Grounding technology has been widely and deeply applied in the field of modern electronics. The "ground" of an electronic device usually has two meanings: one is "earth" (safely) and the other is "system reference ground" (signal ground). Grounding is the establishment of a low-resistance conductive path between the system and a potential reference plane. "Connecting to the earth" is based on the earth's potential and uses the earth as the zero potential to connect the metal casing of the electronic device and the circuit reference point to the earth. Since the capacitance of the earth is very large, it is generally considered that the potential of the earth is zero. At the beginning, the grounding technology was mainly applied to the power system. Later, the grounding technology was extended to the weak current system. Grounding in a weak current system is generally not a grounding that is connected to the Earth in the true sense. For power electronic equipment, the grounding wire is directly connected to the earth or connected to a conductor as a reference potential. When a current passes through the reference potential, the grounding point is a common reference point in the circuit, and the voltage of this point is 0V, the circuit The voltage level of other points in the middle is based on this reference point. Generally, the voltage data of each point marked in the circuit diagram is relative to the grounding point, which can greatly facilitate the voltage measurement in the repair. The line between the same ground points is called the ground line. Connecting the ground plane to the earth is often due to the following considerations: improving the stability of the equipment circuit system, static discharge, and providing safety for the staff. The purpose of grounding: safety considerations, that is, protective grounding. Provides a stable zero potential reference point (signal ground or system ground) shielding protection for the signal voltage.
The safety ground is to connect the outer casing of the high voltage equipment to the ground. One is to prevent the accumulation of electric charge on the casing, causing electrostatic discharge and endangering equipment and personal safety. For example, the grounding of the computer case, the tail of the tanker dragged on the ground, is to release the accumulated electric charge and prevent accidents. Second, when the insulation of the equipment is damaged and the casing is charged, the power supply is protected and the power is cut off to protect the safety of the workers, such as the outer casing of the refrigerator and rice cooker. Third, it can shield the huge electric field of the equipment and protect it, such as the protective rail of the civilian transformer.