Clamp ground resistance tester measures ground faults that cannot be measured by traditional methods
product description
When measuring the grounding system with a loop, the clamp grounding resistance meter does not need to disconnect the grounding down-conductor, and does not need auxiliary electrodes. It is safe, fast, and easy to use. The clamp ground resistance meter can measure the ground fault that cannot be measured by the traditional method, and can be applied to the occasions where the traditional method cannot be measured, because the clamp ground resistance meter measures the comprehensive value of the ground resistance and the ground lead resistance. The clamp ground resistance meter has long jaws and round jaws. The long jaw is especially suitable for the grounding of flat steel.
Measuring principle
1. Resistance measurement principle
The basic principle of measuring grounding resistance with a clamp-on grounding resistance meter is to measure loop resistance. The jaw part of the clamp meter is composed of a voltage coil and a current coil. The voltage coil provides an excitation signal and induces a potential E on the circuit under test. Under the action of potential E, current I will be generated in the circuit under test. The clamp meter measures E and I, and the measured resistance R can be obtained by the following formula.
2. Current measurement principle
The basic principle of measuring current with a clamp ground resistance meter is the same as that of a current transformer. The AC current I of the wire to be measured generates an induced current I1 through the current magnetic ring and the current coil of the jaw, and the clamp meter measures I1, and the measured current I can be obtained by the following formula.
feature comparison
The traditional grounding resistance measurement method is the voltage-current method.
A. Ease of operation
The traditional method must unbuckle the grounding wire and connect the auxiliary grounding electrode. The grounding electrode to be measured is separated from the grounding system; and the voltage electrode and current electrode must be driven into the soil at a specified distance as auxiliary electrodes before measurement can be performed.
With a clamp-type ground resistance tester, you only need to clamp the jaws of the clamp meter around the ground wire to be tested, and the ground resistance value can be read from the LCD screen.
B. Accuracy of measurement
The accuracy of traditional measurement methods depends on the position between the auxiliary electrodes and their relative position to the ground body. If the position of the auxiliary electrode is limited and cannot meet the calculated value, it will bring about the so-called pole layout error.
For the same grounding body, different auxiliary electrode positions may cause a certain degree of dispersion in the measurement results. This scatter can reduce the reliability of the measurement results.
The clamp-type ground resistance tester does not use auxiliary electrodes when measuring, and there is no pole layout error. The consistency of the results was good when the test was repeated.
According to the results of the comparison test between the clamp-type ground resistance tester and the traditional voltage and current method, the relevant national departments can completely replace the traditional ground resistance test method and give credible results for the ground resistance value.
A standard test ring is attached, and the standard test ring can be measured first when measuring. If the reading is accurate, then the measured ground resistance value is trustworthy.
C. Adaptability to the environment
In the traditional method, it is necessary to insert two auxiliary electrodes with relative position requirements, which is the biggest limitation of using the traditional method.
The problem is that with the development of urbanization in our country, no soil can be found around the measured grounding body, and they are all covered by cement. Even if there are so-called green belts, street gardens, etc., their soil is often separated from the soil of the earth. What's more, the relative position of the auxiliary electrode is required when the traditional method is applied to the auxiliary electrode. Finding soils with distance requirements is more difficult in most cases.
When using a clamp-on ground resistance tester, there are no such limitations. Although, from the measurement principle, the clamp-type ground resistance tester must be used in the case of a ground loop, but as long as the user can effectively use your surrounding environment, the clamp-type ground resistance tester can measure single-point grounding system.
