The DIDW-5A earth grid ground resistance tester, also known as ground grid ground resistance tester, large earth grid ground resistance tester, and 5A earth grid ground resistance tester, is suitable for the detection and testing of ground resistance of large power earth grids in power departments, substations, and other units. The 5A earth grid ground resistance tester is suitable for testing the power frequency ground impedance, contact voltage, step voltage, and other power frequency characteristic parameters of various grounding devices, as well as soil resistivity.
Instrument Overview:
Currently, in power systems, the testing of ground resistance of large earth grids mainly adopts the power frequency high-current three-pole method. In order to prevent power frequency interference generated during grid operation and improve the accuracy of measurement results, the insulation preventive test regulations stipulate that the test current for the power frequency high-current method shall not be less than 30A. As a result, there have been many problems such as bulky test equipment, complex test procedures, high labor intensity for test personnel, and long test duration.
The large earth grid ground resistance tester can measure substation earth grids (4Ω), thermal and hydro power plants, microwave stations (10Ω), and lightning rods (10Ω) as a multi-purpose model. It adopts a new type of variable frequency AC power supply, and uses microprocessor control and signal processing measures, which effectively solves the anti-interference problem during the testing process, simplifies the test operation process, improves the precision and accuracy of test results, and greatly reduces the labor intensity and test cost for test personnel.
Performance Features:
1. Good power frequency equivalence. The test current waveform is a sine wave, with a frequency difference of only 5Hz from the power frequency, and measurements are made using both 45Hz and 55Hz frequencies.
2. Strong anti-interference capability. The instrument uses the heterodyne method for measurement, combined with modern software and hardware filtering technology, giving the instrument high anti-interference performance and stable and reliable test data.
3. High precision. The basic error is only 0.005Ω, and it can be used to measure large earth grids with very small ground impedance.
4. Powerful functions. It can measure current stakes, voltage stakes, ground resistance, step voltage, and contact voltage.
5. Simple operation. Full Chinese menu-based operation, directly displaying measurement results.
6. Low labor for wiring, no need for high-current cables.
Technical Specifications:
1. Measurement range: 0～150Ω (including current stake impedance)
2. Resolution: 0.001Ω
3. Measurement error: ±(reading × 2% + 0.005Ω)
4. Maximum output voltage: AC 400V (45Hz, 55Hz, dual frequency, sine wave)
5. Maximum output current: AC 5A (45Hz, 55Hz, dual frequency, sine wave)
6. Current output gears: 5/4.5/4/3.5/3/2.5/2/1.5/1A, with each gear at 0.5A intervals, totaling 9 gears.
7. Anti-interference capability: withstands 50Hz power frequency voltage of 10V
8. Measurement line requirements: current line copper core cross-sectional area ≥1.5mm
voltage line copper core cross-sectional area ≥1.0mm
9. Power supply: AC 220V±10%, 50Hz
10. Dimensions: 440×350×210mm
11. Instrument weight: 30kg
The large earth grid ground resistance tester consists of a high-power variable frequency signal source, coupling transformer, high-precision multi-function frequency-selective multimeter, and other accessories.
