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Will I know how to measure the ground resistance if I have a lightning protection test? actually not
Some people have been doing lightning protection detection for many years, but they still ca n’t or do n’t know how to measure the ground resistance. They think it ’s ok as long as the instrument has a result, but it ’s not. DL / T 845.2-2004 General technical requirements for resistance test devices Part 2: Power frequency ground resistance tester The requirements for ground resistance tester are explained in detail. One of them is that the ground resistance of the current and voltage electrodes (auxiliary ground electrode) cannot be greater than 500Ω, and the smaller the better. These two parameters are shown below, which has important judgment significance for the accuracy of the measured ground resistance. The low-end instruments on the market do not have this function, and it is meaningless to look at the test results of the grounding grid.
1. Use the instrument's original test leads.
2. Before testing, please insert the three wires of the current electrode, voltage electrode and ground electrode to the corresponding terminals of the instrument (one-to-one color), and the three clips at the other end are clipped to each other, that is, short-circuited. Press the test instrument panel On the calibration button to calibrate the line resistance.
3. After calibration of the line group, arrange the positions of the current and voltage electrodes according to the actual site conditions, and perform the first test test on the grounding body. The purpose of the test test is to determine whether the grounding resistance of the current and voltage electrodes is less than 500 ohms. If the instrument displays less than 0.5kΩ, it means that the current and voltage electrode grounding resistances are qualified, and the grounding resistance of the ground network to be tested can be tested normally. If the resistances of the current and voltage electrodes show more than 0.5kΩ, you need to adjust the position of the auxiliary electrode or pour water on the auxiliary electrode to reduce the ground resistance to below 0.kΩ. Press and hold the test button to enter the test mode. If there is only one test mode, press it shortly.
4. During the test, if OL appears on the value displayed by the current, voltage, or ground resistance, you need to determine whether the test lead is conducting. It is recommended to use a multimeter to measure the resistance of the test lead, or use a standard resistance for self-calibration. The test result should be consistent with the standard resistance value, which proves that the line is OK. Before testing, you need to perform the line resistance calibration in step 2.
5. If the test result is 0, make sure that the clamp of the test lead is securely clamped.