Development of Impulse High Current Testing System of Grounding Devices and Testing of Tower Grounding Impulse Characteristics
Xianghan Wang · Gao dianya jishu · 2013
An impulse current testing system of grounding devices is needed to be built so as to simulate the diffusing course of impulse current on grounding devices and in the soil around the devices,and to know well the impulse characteristics of grounding devices.By simulating and project demonstrating,we put forward a technological scheme including four split style impulse current generators arranged uniformly around returning electrodes of circular current whose diameter is 40 meters,in which the charging voltage of single impulse current generator could reach 1 000 kV.The testing system can generate standard lightning impulse current of peak value 100 kA and waveform 8 μs/20 μs on the load whose impedance is larger than 4 Ω.Moreover,equivalency of distribution of impulse current and actual lightning current is expounded and proved by the distribution uniformity of ground potential rise of ground surface and returning electrode of current,and a modified formula of power frequency grounding resistance and impulse grounding resistance is presented according to the testing system.The curve of impulse characteristics of the typical grounding device under the action of impulse current of waveform 8 μs/20 μs and 2.6 μs/50 μs is obtained,indicating that impulse grounding resistance of the device varies insignificantly with the peak value of impulse current.