Instructions for Grounding Resistance Tester
The grounding resistance measuring instrument is a commonly used instrument in the construction, operation, and maintenance of power engineering. It is a special low resistance measuring instrument that uses a hand cranked AC generator as a power source. It has its own characteristics and difficulties in calibration. China has not yet formulated a calibration regulation for grounding resistance meters, and its principle and calibration are briefly analyzed. Method for running and checking the grounding resistance tester: 1. Use two standard resistance boxes with 100m Ω test samples, one less than 100m Ω and one greater than 100m Ω. Adjust the resistance of the testing instrument to 100m Ω and set the current to 10A. 2. Clamp the low input line between the common end of the resistance box and the high voltage output line between the alarm end. Press and hold the "start" button, and the instrument will sound an alarm to prove that the instrument is in good condition. 3. Clamp the common end of the resistor box with the low-end input line, clamp the qualified end with the high-voltage output line, press and hold the "start" button, and if the instrument has no alarm, it proves that the instrument is in good condition.
Specification of grounding resistance tester
Visual inspection of the calibration items for the grounding resistance tester. Whether the appearance of the instrument is damaged, whether the switch buttons are flexible, and whether the digital display indication is incomplete. Are the random attachments complete. Alarm threshold setting error. The standard resistor method is adopted, and the wiring method is the same as the method for verifying the indication error. The verification is carried out at the resistance points of 1 Ω, 4 Ω, 10 Ω, 30 Ω, and 100 Ω. Indicate accuracy check. The two ends of the grounding resistance meter are respectively connected to terminals 14 and 16 of the running instrument; Alarm the grounding resistance tester to the preset value of 1V; the measured value of the grounding resistance tester indicates within 0.1 ohm ± 5% and alarms simultaneously (if indicated, it should indicate 1.0V ± 5%). The tested technical parameters and functions are all normal; The measured value of the grounding resistance tester is within 0.1 ohms ± 5% but there is no alarm. Then, turn the testing terminal from position 14 to position 17. At this point, if the tested grounding resistance tester alarms, it indicates that the technical parameters and functions of the tested instrument are also normal; If the inspection result is outside of the two situations mentioned in the book, it indicates that the inspected instrument is not working properly.
Types of grounding resistance testers
The impact of changes in soil characteristics in the vertical direction is often difficult for us to fully understand, but the influence of such changes on test results is also objectively present. Most projects involve taking soil from the surrounding area and then backfilling during the construction process. When backfilling, construction waste is usually backfilled, and there must be differences in the electrical conductivity between the backfilled construction waste and soil. In addition, there are many gaps in the backfill soil, and the compactness and soil density also differ greatly. Due to the short time, the moisture content of the backfill soil is also not high. This often leads to the loss of authenticity in the detection results. Therefore, during the inspection, it is advisable to find areas with original soil as much as possible and install grounding piles. For areas with shallow backfill soil, the surface backfill floating soil can be removed and the grounding electrode can be installed. This kind of test result is closer to the real situation.
