Test method of grounding continuity resistance tester

(1) The method of measuring the grounding impedance of the grounding grid. In theory, as long as the grounding impedance of the same grounding device is constant, it can be measured offline from any equipment. Measure the grounding resistance values from the grounding down conductors of all power equipments and compare them to determine that the larger one is in poor contact. This method is too labor-intensive and time-consuming, difficult to implement, and the accuracy is not high, it is rarely used now.

(2) Multimeter measurement method. The multimeter measures the resistance between the grounding down conductor and the grounding grid, or between the ground down conductors of adjacent equipment, and subtracting the wire resistance is the measured value. The advantage of this measurement method is simplicity, but the disadvantage is that it is not very accurate.

(3) Grounding rocker measurement method. This method is similar to the multimeter measurement method, but is more effective than that.

(4) Special instrument measurement method. The continuity measuring instrument specially manufactured by the double bridge principle can eliminate the influence of the wire and contact resistance, and make the measurement more accurately and effectively. At present, the ground continuity resistance tester is used, with an accuracy of level 1 and a resolution of 1m2. This method is currently commonly used. The effectiveness of the test is high.

Judgment and processing of measurement results

The judgment method differs depending on the detection method. The first measurement method is rarely used in the field, has no practical experience, and lacks judgment standards. However, compared with each other, the measured value can also be further compared with other methods.

Multimeter measurement shows that below 1 is good, above 1 is bad, and above 30Q is severely corroded and fractured, it should be excavated and inspected as soon as possible.

Grounded rocker measurement, less than 0.2 is good.

The measurement by special instruments is good and 200m~12 is bad. Key equipment should be excavated and handled as soon as possible, and other equipment should be checked and handled in due course. 1 The above is closed, please proceed with excavation immediately. When the measured value is significantly larger than other equipment, please follow up the measurement.

Measurement considerations

(1) When measuring, select the lead that is well connected to the main network as the reference point, and measure the resistance of the lead of other equipment and the reference point. If there are many devices in the test results that have poor offline testing, it is recommended to consider reselecting the reference point.

(2) Compared with the initial value, the measured value should be less than 1.5 times the initial value. Otherwise, please check further.

(3) In order to compare past data, it is best to keep the position of each measurement reference point constant.

(4) Strictly control the resistance of the pull-down conductor of the main equipment (transformer, lightning rod, arrester, etc.). When these devices fail, a large current will flow, which is easy to burn.