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INTRODUCTION
Currently in the electric system, the grounding resistance of large grounding grid is mainly measured with the high power frequency current three-pole method. In order to prevent the power frequency interference generated in the operation of the power grid and increase the accuracy of the measuring results, it's stipulated in testing regulations of the insulation prevention that the testing current of the heavy power-frequency current method shall be no less than 30A. And thus many problems emerge, such as heavy testing equipment, complex test procedures, high working strength of the test personnel and long duration. The grounding resistance tester can measure on the facilities of the grounding grid at the transformer substation (4Ω), hydraulic/heat-engine plant, microwave station (10Ω) and lightening rod (10Ω). New variable frequency power is used and measures like the microcomputer processing controlling and signal controlling are adopted, perfectly solving the issues of interfering prevention in the testing process, simplifying the operation, increasing the accuracy and veracity of the testing results and reducing the labor intensity and testing cost of the testing personnel. The instrument can be used to measure power-frequency grounding impedance, grounding resistance and the auxiliary instrument and other characteristic parameters of various grounding devices as well as earth resistivity. Pilot frequency anti-resistance technology is applied to the instrument, enabling it to accurately measure the data under the power frequency of 50Hz. The highest testing current is 5A, which would not cause high potential of the grounding device and it has great anti-interference ability, so it can carry out the test with persistent power supply. |
MAIN FEATURES
1. Good power frequency equivalence of test. The testing current is displayed in the form of sine wave, of which the frequency is only 5 Hz different from the power frequency. The frequencies of 45Hz and 55Hz are used for test. |
2. Strong anti-interference capability. The pilot frequency method is used for test in the instrument, with the modern hardware and software filtering technology, giving the instrument high anti-interference ability with stable and reliable testing results. |
3. High accuracy. Its intrinsic error is only 0.005Ω, making it feasible to measure the large grounding grid with little grounding impedance. |
4. Powerful function. It is possible to measure current piles, voltage piles, grounding resistance, auxiliary instrument and earth resistivity. |
5. Simple operation. Chinese menu-type operation directly shows the measuring results |
6. A small sum of labor in wiring and no need of large current line. |
TECHNICAL SPECIFICATION
Range of testing for impedance: 0Ω-200Ω | Range of testing for impedance: 0Ω-200Ω |
Resolution ratio: 0.001Ω | Resolution ratio: 0.001Ω |
Measuring error: ±(reading ×2%+0.005Ω) | Measuring error: ±(reading ×2%+0.005Ω) |
Anti-interference ability under the power frequency of 50Hz: 10V | Anti-interference ability under the power frequency of 50Hz: 10V |
Waveform of testing current: sine wave | Waveform of testing current: sine wave |
Frequency of testing current: Dual-frequency of 45Hz, 55Hz | Frequency of testing current: Dual-frequency of 45Hz, 55Hz |
Maximal output current: 5A | Maximal output current: 5A |
Maximal output voltage: 400V | Maximal output voltage: 400V |
Requirements of measuring line: Sectional area of copper core of current line is ≥2.0mm2 Sectional area of copper core of voltage line is ≥1.5mm2 | Requirements of measuring line: Sectional area of copper core of current line is ≥2.0mm2 Sectional area of copper core of voltage line is ≥1.5mm2 |
Power supply: AC220V±10%, 50Hz | Power supply: AC220V±10%, 50Hz |
Boundary dimension: 440×350×210 | Boundary dimension: 440×350×210 |
Weight of the instrument: 10kg | Weight of the instrument: 10kg |