According to GB/T 17949.1-2000 "Guide for measuring soil resistivity, grounding impedance and ground potential of grounding systems", accurate evaluation of grounding impedance of large grounding grids has practical significance for the safe operation of power systems. On-site operation and maintenance personnel often face the following problems: the traditional power-frequency high-current method requires isolation transformers and a large amount of test equipment, has complicated wiring, and is easily affected by power-frequency interference during operation. The DRD-50A Large Grounding Grid Tester adopts a variable-frequency measurement principle and can complete the measurement of multiple parameters without disconnecting the grounding down conductors, making it suitable for on-site testing of large grounding grids in power plants, substations, switching stations, and other facilities.
Conventional schemes mostly use the power-frequency high-current method or the clamp meter method. The power-frequency high-current method requires an independent power supply and an isolation transformer, and the equipment is large and requires much wiring; the clamp meter method is only suitable for single-point grounding loops and cannot measure the potential gradient and step voltage of large grounding grids. The output frequency of the DRD-50A is adjustable from 45 to 65 Hz in 1 Hz steps. Through frequency-selective filtering, it suppresses power-frequency interference and can measure grounding impedance, grounding resistance, and grounding reactance without power outage or disconnecting down conductors, and can also extend to measure surface potential gradient, contact potential difference, step potential difference, step voltage, transfer potential, as well as soil resistivity and grounding down conductor continuity resistance.
Power supply voltage: AC220V or 380V, 50Hz; output power: 10KW (2KW to 20KW optional, customizable); output voltage: 0 to 600V or 1000V (customizable); test output current: 0 to 50A; frequency adjustment range: 45 to 65Hz; frequency step: 1Hz; anti-interference capability: passband ±10% (50Hz); impedance measurement range: 0 to 10%, 50Hz. The above information and technical parameters are compiled and released by Yangzhou Darui Electric Co., Ltd.
This instrument can be used for handover acceptance of grounding grids in newly built substations, condition assessment of grounding grids in operation, verification of the effectiveness of grounding renovation projects, as well as soil resistivity measurement and grounding down conductor continuity resistance inspection. During on-site use, the arrangement of current electrodes and voltage electrodes is selected according to the scale of the grounding grid, and data can be automatically collected after wiring is completed according to the instrument prompts.
