By hvhipot 
When measuring a grounding system with a loop, the clamp ground resistance tester does not need to disconnect the ground down conductor, does not require auxiliary electrodes, is safe and fast, can measure ground faults that cannot be measured by traditional methods, and can automatically detect each interface The connection status, the interference voltage of the ground grid, the interference frequency, and the unique functions such as value retention and intelligent prompts, so it is deeply loved by power workers. What is the working principle of the clamp ground resistance tester?
How to use the clamp-type ground resistance tester to accurately measure the ground resistance.
First of all, it is necessary to understand the working principle of its precise measurement. The clamp-type ground resistance tester is used to accurately measure the ground resistance of any system with a control loop. The instrument itself can generate a power supply potential, and it can generate current in any system with a control loop. Therefore, its precise measurement working principle is in short It is Ohm’s law of the whole circuit, which measures the loop resistance value of this control loop system.
Using a clamp-type grounding resistance tester to accurately measure the grounding resistance of power line towers is simple, and the accurate measurement results are highly accurate, but it can only be used on high-voltage lines with overhead ground wires. During accurate measurement, only one grounding lead is allowed for the tower to be tested. Downline, if the ground network of each tower foot is not connected, the ground down conductor of the remaining feet should be disconnected and then connected with the down conductor of the precise measuring foot with a temporary wire (the connection point is under the clamp meter). Through the analysis of the accurate measurement results, it can be judged whether the ground grid of each tower foot is connected, and whether the grounding down conductor generally has the hidden danger of poor contact.
―. Development and selection of grounding resistance tester
Grounding resistance tester is a common instrument for testing and accurately measuring grounding resistance. It is also an indispensable special tool for electrical equipment safety inspection and grounding engineering completion acceptance. In recent years, due to the rapid development of Internet technology, grounding resistance testers have also penetrated a large number of Microprocessor technology, its precise star measurement function, content and precision are incomparable to ordinary instruments. Nowadays, advanced ground resistance testers can meet all requirements for accurate grounding measurement. Using the new jaw method, there is no need for piling construction to set up the line for on-line direct and accurate measurement. A powerful ground resistance tester is controlled by a microprocessor, which can automatically detect the connection status of each interface and the electromagnetic interference voltage and electromagnetic interference frequency of the ground network, and has unique functions such as constant value maintenance and intelligent prompts.
2. Ground resistance tester and development
At first, people used the volt-ampere method to measure the grounding resistance. This type of test is very primitive. Use the ammeter and voltmeter measurement method. When measuring resistance, you must first estimate the size of the current, select an insulated wire with a suitable cross-section, and make full use of the variable resistance R to adjust the current during the preliminary test. When the formal measurement is performed, the variable resistance is short-circuited by an ammeter and a voltmeter. The obtained value can calculate the grounding resistance.