The grounding resistance tester under UHV power can help many power workers conduct various power tests more conveniently.
What is a grounding resistance tester?
The resistance between the grounding electrode and the earth is usually referred to as the grounding resistance. More precisely, grounding resistance is the sum of the resistance of the grounding conductor, the contact resistance between the grounding conductor and the earth, and the earth's resistance. The difference between grounding resistance and ordinary resistance is that it has the following special characteristics:
• Polarization effect
Due to the fact that the behavior of the earth is similar to that of an electrolyte, it has a polarizing effect, and direct current generates an electromotive force in the opposite direction, making it impossible to measure accurately. Therefore, grounding resistance is usually measured using square or sine waves with frequencies ranging from tens of hertz to 1 kHz.
• Special measurement settings
The grounding resistance is the resistance between the grounding electrode and the earth. It is impossible to measure without inserting the electrode into the ground. Due to the low resistivity of the earth, a voltage drop occurs near the electrode through which the current used for measurement flows. Therefore, in order to accurately measure the resistance value of each grounding electrode (E electrode, S [P] electrode, and H [C] electrode), you must move a distance of approximately 10 meters.
• There is interference present
The measurement of grounding resistance is subject to interference such as grounding potential and the influence of auxiliary grounding electrodes. The grounding potential caused by the leakage current of the equipment connected to the grounding electrode is superimposed on the signal detected by the grounding resistance tester, affecting the measured value. In addition, if the auxiliary grounding electrode has a high grounding resistance, the measured current will decrease, making the measurement more susceptible to noise such as grounding potential.
