Ground Resistance Tester is used to measure the internal grounding resistance of electrical equipment, reflecting the (contact) resistance between the exposed conductive parts of the equipment and the main grounding terminal. To eliminate the influence of contact resistance on the test, the tester adopts a 4-terminal measurement method, applying a current (typically around 25A) between the exposed conductive parts and the main grounding terminal, then measuring the voltage across these two points to calculate the resistance value.
Ground Resistance Tester is widely used in electric power, post and telecommunications, railways, petroleum, chemical, communications, mining and other departments to measure the grounding resistance of various devices, as well as the resistance of low-resistance conductors, and can also measure soil resistivity and ground voltage.
Ground Resistance Tester precautions are as follows:
1. When using the Ground Resistance Tester, pay attention to the position where the current probe is inserted into the soil, ensuring that the ground rod is in a zero-potential state.
2. The test should preferably be conducted when soil resistivity is high, such as in early winter or during dry summer seasons. Measurements cannot be taken after rain, when the soil absorbs too much moisture, or during drastic changes in climate, temperature, pressure, etc.
3. Some switch components of the Ground Resistance Tester cannot be independently connected across active circuits for differential mode protection; to avoid power supply short circuits, a voltage-limiting component must be connected in series.
4. There should be no stray currents or polarized soil near the ground electrode under test.
5. When measuring protective grounding resistance, be sure to disconnect the electrical equipment from the power supply connection point. When measuring grounding resistance less than 1Ω, use dedicated wires to connect to the ground body separately, with C2 on the outside and P2 on the inside.
6. The connecting wires should use well-insulated conductors to avoid leakage in the Ground Resistance Tester.
7. When storing this meter, pay attention to ambient temperature and humidity; it should be placed in a dry and ventilated place, avoid moisture, and prevent contact with acids, alkalis, and corrosive gases.
8. When measuring the grounding resistance of large grounding grids, do not follow the general wiring method; refer to the regulations in the ammeter-voltmeter measurement method to select the insertion points.
9. When measuring ground resistance, repeat the measurement 3 to 4 times in different directions and take the average value.
10. This meter is dual-purpose AC/DC; when AC power is not connected, the meter uses battery power; when AC is connected, AC power is preferred.
11. When the upper left corner of the meter head displays “←”, it indicates low battery voltage, and new batteries should be replaced. If the meter is not used for a long time, remove all batteries to prevent corrosion of the meter.
