The grounding resistance tester adopts the advanced medium and large scale integrated circuit, and uses DC/AC conversion technology to combine the measurement methods of three and four knobs into a new type of grounding resistance meter. The working principle is that the DC/AC converter inside the machine changes the DC into the low frequency constant current of THE AC, through the auxiliary grounding pole C and the measured object E constitute a loop, the measured object produces AC voltage drop, through the auxiliary grounding pole P into the AC amplifier amplification, and then through the detection into the meter head display. With the help of the rate switch, three different limits can be obtained: 0 ~ 2 ω, 0 ~ 20 ω, and 0 ~ 200 ω.

Grounding resistance tester is a major breakthrough of traditional grounding resistance measurement technology, widely used in electric power, telecommunications, meteorology, oil field, construction and industrial electrical equipment grounding resistance measurement. In the measurement of the grounding system with a loop, there is no need to disconnect the grounding lead line, no need for auxiliary electrode, easy to use. It can measure the grounding fault which cannot be measured by the traditional method, and can be applied to the occasion which cannot be measured by the traditional method, because the measurement is the combined value of the grounding body resistance and the grounding lead resistance.

Measuring steps of grounding resistance tester:

1) insert the two grounding probes into the ground 20m and 40m away from the grounding body along the radiation direction of the grounding body, and the insertion depth is 400mm.

2) Put the tester flat near the grounding body, and wire connection.

3) After placing the measuring instrument horizontally, check whether the pointer of the galvanometer points to the center line. Otherwise, adjust the "zero regulator" to make the pointer of the grounding resistance tester point to the center line.

4) The "multiplier scale" (or coarse adjustment knob) at the maximum multiple, and slowly turn the generator handle (pointer began to offset), while rotating the "measuring scale plate" (or fine adjustment knob) so that the galvanometer pointer to the center line.

5) When the pointer of the galvanometer is close to balance (the pointer is close to the center line), shake the handle to make the speed reach above 120r/min, and adjust the "measuring dial" to make the pointer point to the center line.

6) If the reading of the "measuring scale plate" is too small (less than 1), it is not easy to read accurately, indicating that the multiplier scale multiple is too large. At this time, the "multiplier scale" should be placed at a smaller multiple, readjust the "measuring dial" so that the pointer points to the center line and an accurate reading is read.

7) Calculate the measurement result, that is, R = "multiplier scale" reading x "measurement dial" reading.

Precautions for measurement:

(1) During measurement, the grounding device line should be disconnected from the protected equipment to ensure accurate measurement.

(2) If there is a metal pipe or cable connected with the measured grounding pole near the detection needle, the potential of the whole measurement area will have a certain equalization effect, affecting the measurement results. In this case, the distance between the current detection pin C and the metal pipe or cable should be greater than 100m, and the distance between the potential detection pin P 'and the metal pipe or cable should be greater than 50m. If the metal pipe or cable is not connected to the ground loop, the distance can be reduced by 1/2 to 2/3.

(3) When the sensitivity of the galvanometer is too high, the potential detection needle P 'can be inserted into the soil shallower; When the sensitivity of the galvanometer is insufficient, the soil between the potential probe needle P 'and the current probe needle C' can be moistened with water.

(4) when the distance between the grounding pole E and the current detection needle C 'is greater than 20m, the position of the potential detection needle P' can be inserted in the straight line between E 'and C', at this time the measurement error of the grounding resistance tester can be excluded; If the distance between the ground pole E 'and the current detection pin C' is less than 20m, insert the potential detection pin P 'between the straight line of E' and C '.