The grounding resistance, also known as grounding impedance, is tested to ensure that after the basic insulation of the product fails, the protective grounding can effectively and reliably lead dangerous voltage to the ground, without causing harm to human health
In Chapter 5.7.5 of IEC/EN 62368-1, Chapter 2.6.3.4 of GB 4943.1, and Chapter 15.2 of GB 8898, detailed provisions are made for hazardous voltage testing. The testing methods in the standard are basically the same, and the requirements for determining the results are consistent. All electronic and electrical products with grounding are applicable to this test
When testing the grounding resistance project, if the test results are only used domestically, a laboratory with CMA qualification should be selected. When the test results are used internationally, a laboratory with CNAS qualification should be selected and tested in an environment with an ambient temperature of 15-35 ℃ and a humidity of below 75%.
Grounding resistance testing is required in certifications such as CB, UL, and CCC. The testing will use safety equipment such as grounding resistance testers and stopwatches. The equipment used must be calibrated by a qualified organization and be within the validity period
The specific testing method is as follows:
GB8898 standard:
1. The testing position is the farthest part of the input ground point to the protective ground.
2. The test voltage should not exceed 12Vac, the test current should be 25A, and the time should be 1 minuteIEC/EN 62368-1, GB4943.1 standards:
1. The output end of the grounding resistance tester is connected to the grounding terminal of the input end of the test object, and the other end is connected to the farthest end where the shell of the test object is connected to the grounding terminal.
If the rated protective current of the tested sample circuit exceeds 16A, set the output current of the grounding resistance tester to twice the rated protective current for 2 minutesThe judgment results of the three standards are:
The grounding impedance of the product should be less than 0.1 Ω.
. After the test, protect the connecting conductor from damageThe grounding resistance test is a relatively dangerous test, which can generate large currents. Therefore, it is necessary to pay attention to safety during the test. During the testing process, it is important not to touch the tested sample with your hands or any part of your body, otherwise there is a risk of electric shock
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