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Potential drop method of ground resistance tester

time:2021/3/8   source:华天电力  reading:240 time

To measure resistance, we use a ground resistance tester to apply a voltage between its terminals to circulate the current through the terminals. One of the terminals is ground-contactable E. By definition, the second terminal is any other point on the earth, which is actually far away D one, in order to measure, the auxiliary electrode H should be hammered at this time, the second electrode must have its own ground resistance and resistance area, we will see:

1. Measure the ground resistance of electrode E. If the conventional resistance measurement between point E and point H is measured by measuring voltage and circulating current, the total ground resistance of the two electrodes is obtained instead of the ground resistance of electrode E. It is very important because the H-type is very small compared to the E. Due to the condition of the auxiliary electrode itself, its contribution to the total resistance may be very important, resulting in a considerable error.

2. It can be considered that the auxiliary electrode h is far enough away from the grounding system. When the corresponding resistance area does not overlap, the resistance can be measured. In this case, all the volumes outside the resistance area are very close to the same potential, so that the development can be done. The following measurement methods.

In order to avoid the introduction of errors in the ground resistance of the electrode H, a third electrode S is used, and the S rod is hammered at any position outside the E and H influence zones, which results in different geometrical structures.

Earth Resistance Tester.png

This arrangement is called the drop-of-potential method. It is a common method for measuring grounding resistance in small and medium-sized systems. In this method, the distance between the resistance zones is obtained by maintaining a reasonable distance between the electrodes. The current is in the grounding system E Circulate in the auxiliary electrode H, and measure the voltage between E and the third electrode S. This voltage is the potential drop generated by the test current in the grounding system resistance Rx, which can be measured without being affected by the ground resistance of the H rod.

1. Accurately measure the large ground resistance tester and ground reactance.

2. The surface potential gradient of a large-capacity grounding grid with fine internal quantities.

3. Accurately control and measure the contact potential difference, contact working voltage, step potential difference, and step voltage of a large-scale system grounding grid.

4. Accurately measure the transmission potential of a large grounding grid.

5. Measure the on-resistance of the down conductor of the system grounding.

6. Measure soil resistivity.

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