I.Instrument overview
At present, in the power system, the grounding resistance test of the earth network mainly adopts the power frequency high current three-pole method. In order to prevent the power frequency interference generated during the operation of the power grid and improve the accuracy of the measurement results, the insulation preventive test regulations stipulate that the test current of the power frequency high current method shall not be less than 30A. As a result, many problems such as heavy test equipment, complicated test process, high work intensity of test personnel, and long test time appeared.
The ground network earth resistance tester adopts a new variable frequency AC power supply, and adopts a microcomputer to control the earth network ground resistance tester and signal processing. It solves the anti-interference problem during the test and simplifies the test operation process. , Improve the accuracy and accuracy of the test results, greatly reduce the labor intensity of the test personnel and test costs.
The ground network earth resistance tester adopts a new variable frequency AC power supply is a special instrument for measuring the grounding resistance of the earth grid and the ground continuity between the grounding points. The instrument adopts frequency conversion anti-interference technology, does not need high current measurement, and can measure accurate data of 50Hz in the strong interference environment of the substation. The measurement results are displayed by the large-screen LCD, and the built-in micro printer can be printed out. The instrument can measure ground impedance and ground resistance at the same time, which can more truly reflect the actual characteristics of the ground network.
II.Main Technical index
1. Measuring range: 0～5000Ω (including current pile impedance)
2. Resolution: 0.001mΩ
3. Measurement error: ±(reading×2%+0.005Ω)
4. Anti-power frequency 50Hz voltage interference capability: 10V
5. Test current waveform: sine wave
6. Test current frequency: Single frequency: 40-70Hz, resolution 0.1Hz, free setting
Dual frequency: 50±0.1Hz to 50±10.0Hz can be set at will
60±0.1Hz to 60±10.0Hz can be set freely
7. Output current: 5A or external power supply 30A
8. Output voltage: 400V or external power supply 1000V
9. Measuring line requirements: Current line copper core cross-sectional area ≥1.5mm2
Voltage line copper core cross-sectional area ≥1.0mm2
10. Test power supply: Built-in 2kW variable frequency power supply or external high-power variable frequency power supply.
11. Power supply: AC220V±10%, 50Hz
12. Dimensions: 500mm*377mm*330mm, instrument weight: 20kg