1. What is the general test value of grounding resistance?
1. If it is an independent lightning protection grounding resistance, it should be less than 10 ohms.
2. If the safety grounding resistance is less than 4 ohms.
3. The AC resistance is less than 4 ohms.
4. The DC grounding resistance is less than 4 ohms.
5. Anti-static resistance is less than 100 ohms.
2. What is grounding resistance?
The grounding resistance is the resistance encountered when the current flows from the grounding device into the ground and then flows through the ground to another grounded body or spreads far away. The grounding resistance value reflects the good degree of contact between the electrical device and the "ground" and reflects the scale of the grounding grid.
3. Instruments for measuring grounding resistance
The grounding resistance tester is a new type of digital grounding that abandons the traditional manual hand-cranked power generation work method, adopts advanced large-scale integrated circuits, and applies DC/AC conversion technology to combine the three-terminal button and four-terminal button measurement methods into one model. Resistance tester. It is suitable for measuring the grounding resistance of various devices and measuring the resistance of conductors with low resistance in electric power, post and telecommunications, railways, communications, mining and other departments; this meter can also measure soil resistivity and ground voltage.
4. Matters needing attention when measuring grounding resistance
It is not allowed to test the grounding resistance value of the grounding device with electricity.
When measuring, the measuring probe should choose a location with good soil. If the indicator is found to be unstable during the measurement, it can be buried at the depth of the probe in the ground at an appropriate high speed, or an appropriate amount of water can be poured into the ground. If there are pipelines or cables underground, another location should be selected.
The grounding resistance tester is not allowed to open the handle, otherwise the grounding resistance tester will be damaged.
Since the soil moisture has a great influence on the grounding resistance, it is not suitable to measure the grounding resistance after it has just rained.
When using the grounding resistance tester, try to eliminate the interference of the zero-sequence current on the grounding body and the interference of the mutual inductance of the leads on the measurement results.
The resistance of the voltage electrode and the current electrode should generally not be greater than 1000~20000. When measuring a small grounding resistance, it should not be greater than 100~2000.
When measuring the grounding resistance, repeat the measurement three to four times, and take the arithmetic mean value as the measured grounding resistance.