The DIDW-5A ground grid earth resistance tester is also known as the ground grid earth resistance tester, large ground grid earth resistance tester, and 5A ground grid earth resistance tester. The 5A ground grid earth resistance tester is suitable for testing the earth resistance of large power ground grids in power departments, substations, and other units. It is applicable for measuring the power frequency grounding 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 grounding resistance for large ground grids mainly adopts the power frequency high-current three-pole method. 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, problems such as bulky test equipment, complex testing procedures, high labor intensity for test personnel, and long testing time have emerged.
The large ground grid earth resistance tester can measure substation ground grids (4Ω), hydro and thermal power plants, microwave stations (10Ω), and lightning rods (10Ω) as a multi-purpose model. It adopts a new variable frequency AC power supply, and uses measures such as microcomputer processing control and signal processing, which effectively solve the anti-interference problem during testing, simplify the test operation process, improve the accuracy and precision of test results, and greatly reduce the labor intensity and testing 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 two frequencies: 45Hz and 55Hz.
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, making it suitable for measuring large ground grids with very small grounding impedance.
4. Powerful functions. It can measure current stakes, voltage stakes, grounding resistance, step voltage, and contact voltage.
5. Simple operation. Full Chinese menu-based operation, directly displaying measurement results.
6. Low wiring labor, 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 a step of 0.5A, totaling 9 gears.
7. Anti-interference capability: withstands power frequency 50Hz 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 ground grid earth resistance tester consists of a high-power variable frequency signal source, coupling transformer, high-precision multi-function frequency-selective multimeter, and other accessories.
