During completion acceptance and periodic testing of large grounding grids at substations and power plants, O&M personnel frequently encounter several practical problems: power-frequency interference causes measurement data to fluctuate, and repeated measurements yield inconsistent results; large grid areas and long diagonals make wiring difficult and output power insufficient for traditional test equipment; and on-site needs to simultaneously measure grounding impedance, continuity resistance, and soil resistivity require transporting multiple instruments back and forth. These problems directly affect testing efficiency and data traceability.
The DRD-100A Large Grounding Grid Impedance Tester is designed for the above scenarios, adopting variable-frequency anti-interference technology to stably output measurement results in substation environments with strong power-frequency interference. The instrument integrates grounding impedance, continuity resistance, and soil resistivity measurement functions, covering the main items of grounding grid completion acceptance and periodic testing with a single device, reducing on-site equipment switching.
AC voltage range 0–600V, accuracy class 0.5; AC current range 0–120A, accuracy class 0.5; active power range 0–72kW, accuracy class 1.0; frequency measurement range 45–75Hz, accuracy class 0.2. Operating power supply is AC 220V±10%, suitable for conventional on-site power conditions. The instrument output power meets the testing requirements of large and medium-sized grounding grids, and the wiring method can be flexibly adjusted according to the on-site grid structure.
The instrument is suitable for grounding impedance measurement of large grounding grids at power plants and substations, and can also be used for continuity resistance and soil resistivity testing of grounding devices in large building complexes. During on-site operation, it is recommended to perform a no-load verification after the current electrode and voltage electrode are arranged, and confirm reliable lead connections before starting measurement. During measurement, pay attention to maintaining a difference between the test frequency and the power frequency to reduce interference effects. For larger grounding grids, test electrodes can be arranged using the diagonal method, and ambient temperature and humidity should be recorded for data comparison.
The instrument panel uses Chinese labels, and the operation process is guided step by step according to measurement items. After on-site use, clean the terminals, check the test lead insulation for damage, and store in a dry and ventilated environment. Regular calibration can ensure measurement accuracy meets the class 0.5 requirement. An operation manual is included, detailing the wiring diagrams and parameter setting methods for each measurement mode.
