The manufacturer of flexible graphite grounding strips reminds you that grounding resistance refers to the resistance encountered when current enters the ground through the grounding body and spreads to the surrounding area. The earth has a certain resistivity, and if there is current flowing through it, different potentials will exist in various parts of the earth. After the current is injected into the ground through the grounding body, it spreads in the form of a current field to all directions. The farther away from the grounding point, the larger the hemispherical scattering area, and the lower the current density in the ground. Therefore, it can be considered that at a distance of 15-20 meters, the resistance per unit diffusion distance and the current density in the ground are close to zero, and the potential at that point is already zero. The curve U=f (r) in the figure represents the potential distribution on the ground surface (r represents the distance from the lightning current injection point).

The grounding device is composed of a metal grounding body (angle steel, flat steel, steel pipe, etc.) buried in the soil and a grounding wire for connection.

According to the purpose of grounding, electrical equipment grounding can be divided into: working grounding, lightning protection grounding, protective grounding, and instrument control grounding.

Working grounding: It is the grounding required to ensure the normal operation of the power system. For example, in a neutral point direct grounding system, the neutral point grounding of a transformer is used to stabilize the potential of the power grid to ground, thereby reducing the insulation to ground.

Lightning protection grounding: It is a grounding system designed to meet the needs of lightning protection. For example, the grounding of lightning rods (wires) and lightning arresters is aimed at facilitating the smooth introduction of lightning current into the earth, in order to reduce lightning overvoltage, hence it is also known as overvoltage protection grounding.

Protective grounding: also known as safety grounding, is a grounding set up for personal safety, that is, the electrical equipment casing (including cable skin) must be grounded to prevent the casing from being electrified and endangering personal safety.

Instrument control grounding: Grounding set up for the thermal control system, data acquisition system, computer monitoring system, transistor or microcomputer relay protection system, and remote communication system of power plants to stabilize potential and prevent interference. Also known as electronic system grounding.

The basic concept of grounding resistance:

The manufacturer of flexible graphite grounding strips reminds you that grounding resistance refers to the resistance encountered when current enters the ground through the grounding body and spreads to the surrounding area. The earth has a certain resistivity, and if there is current flowing through it, different potentials will exist in various parts of the earth. After the current is injected into the ground through the grounding body, it spreads in the form of a current field to all directions. The farther away from the grounding point, the larger the hemispherical scattering area, and the lower the current density in the ground. Therefore, it can be considered that at a distance of 15-20 meters, the resistance per unit diffusion distance and the current density in the ground are close to zero, and the potential at that point is already zero. The curve U=f (r) in the figure represents the potential distribution on the ground surface (r represents the distance from the lightning current injection point).

The manufacturer of flexible graphite grounding strips reminds you that the ratio of the potential Um at the grounding point to the grounding current I is defined as the grounding resistance R at that point, where R=Um/I. When the grounding current is constant, the smaller the grounding resistance, the lower the potential Um, and vice versa, the higher the potential Um. The grounding resistance mainly depends on the structure, size, depth of burial, and local soil resistivity of the grounding device. Due to the much lower resistivity of metal grounding bodies compared to soil resistivity, the resistance of the grounding body itself can be neglected in the grounding resistance.