Maandusvastus

Maandusvastus refers to the electrical resistance of a grounding system. It is a critical parameter in ensuring electrical safety and the proper functioning of electrical installations. A low earth resistance is essential for safely dissipating fault currents into the ground, thereby preventing dangerous voltage buildups on conductive surfaces.

The grounding system typically consists of grounding electrodes buried in the earth and conductors connecting these electrodes to the electrical equipment. The earth itself acts as the ultimate sink for electrical current. The total resistance of the grounding system is the sum of the resistance of the grounding electrodes and the resistance of the connecting conductors.

Factors influencing earth resistance include the resistivity of the soil, the size and shape of the grounding electrodes, the depth at which they are buried, and the moisture content of the soil. Soil resistivity can vary significantly depending on geographical location, soil composition, and seasonal changes. For instance, dry, rocky soil generally has a much higher resistivity than moist, clay-rich soil.

Measuring earth resistance is a standard procedure in electrical system commissioning and maintenance. Various methods and instruments are used for this measurement, with the fall-of-potential method being a common technique. Regular testing ensures that the grounding system remains effective and meets the required safety standards.

A high earth resistance can lead to inadequate protection against electric shock and can impair the operation of protective devices like circuit breakers and surge protectors. Therefore, maintaining a low and stable earth resistance is paramount for the safety and reliability of any electrical system.