The grounding resistance tester is a common instrument for testing and measuring grounding resistance. It is also an indispensable tool for electrical safety inspection and grounding engineering completion acceptance. Due to the rapid development of computer technology in the past years, the grounding resistance tester has also penetrated a large number of microprocessor technology , Its measurement function, content and accuracy are incomparable to ordinary instruments. At present, the advanced ground resistance tester is a common instrument for testing and measuring grounding resistance, and it is also an indispensable tool for electrical safety inspection and grounding engineering completion acceptance. In recent years, due to the rapid development of computer technology, the grounding resistance tester has also penetrated A large number of microprocessor technology, its measurement function, content and accuracy are incomparable to ordinary instruments. The current advanced ground resistance tester can meet all grounding measurement requirements. The use of the new jaw method eliminates the need for pile driving and laying line for online direct measurement. A powerful ground resistance tester is controlled by a microprocessor, which can automatically detect the connection status of each interface and the interference voltage and frequency of the ground network, and has unique functions such as value retention and intelligent prompts. Grounding resistance test and development At first, people used volt-ampere method to measure grounding resistance. This kind of test is very primitive. Figure 1 shows the measurement method using an ammeter and a voltmeter. When measuring the resistance, you must first estimate the size of the current, select an insulated wire with a suitable cross-section, and use the variable resistance R to adjust the current during the preliminary test. When the formal measurement is performed, the variable resistance is short-circuited, which is obtained by an ammeter and a voltmeter. The value of can calculate the grounding resistance. Voltammetric measurement of ground resistance has obvious shortcomings. First, it is troublesome, cumbersome and heavy. During the test, the grounding rod is 20-50 meters away from the ground electrode, and the auxiliary grounding distance is at least 40-100 meters grounded. In addition, it is greatly affected by external interference, and sometimes it is almost impossible to measure in the strong voltage area. In the 1950s and 1960s, the Soviet E-type shaking table replaced the voltammetry method. It is easy to carry and a hand-cranked generator, so the workload is simpler than that of the voltammetry method. In the 1970s, domestic grounding resistance meters were introduced, such as ZC-28 and ZC-29. Regardless of structure, volume, weight, measuring range, graduation value, and accuracy, they were better than the'E'-type shake meter. Therefore, for quite a period of time, grounding resistance meters are represented by the ZC series produced by Shanghai Liubiao Factory. The accuracy of the above-mentioned instrument is not high due to the hand-cranked generator. The use of the digital ground resistance tester in the 1980s brought vitality to ground resistance testing. Although the test wiring method is no different from the ZC series, its stability is much higher than that of the shaker pointer type. One of the pioneering achievements of the true earth resistance tester was the birth of the jaw-type earth resistance tester in the 1990s, which broke the traditional test method. For example, the 6411 clamp ground resistance tester produced by French CA company can be called a great revolution in ground resistance testing. The biggest feature of clamp ground resistance test is that there is no need for auxiliary ground rods. As long as the ground wire or ground rod is clamped, the ground can be measured. resistance. The above ground resistance tester is in the form of a single jaw, which has its advantages of rapid testing and simple operation, but it also has low accuracy. The ground resistance is less than 0.7Ω and cannot be distinguished. Let alone the single jaw type ground resistance. The instrument is mainly used to check the multi-electrode grounding network connected above the ground, and to query the ground resistance measurement through the loop ground resistance. The measuring range and accuracy of GEOX double-jaw grounding resistance meter have been improved. However, because of the electromagnetic induction principle used in the measurement of the jaw method, it is susceptible to interference, and the measurement error is relatively large, which cannot meet the requirements of high-precision measurement. The recently introduced 234 digital precision grounding resistance meter from Italy HT company perfectly combines the characteristics of traditional voltammetry measurement with the new technology principle of jaw method, and then uses advanced computer control technology to become the contemporary leading intelligent ground resistance measurement. instrument. It has the characteristics of high accuracy, complete functions, and easy operation. It can be widely used in power telecommunication systems, building buildings, airports, railways, oil tanks, lightning protection devices, high-voltage towers and other grounding resistance measurements. Currently, it has been deployed in the domestic post and telecommunications, electric power, aviation and other industries.
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