Anotace:
When a high magnitude of current discharged to the ground, a large potential gradient will result in, which will exhibit a ground potential rise (GPR), or induced voltage. This GPR usually decays with distances, depending on the soil resistivity, ground electrode sizes, configurations and steady state resistance, RDC, values. The GPR value not only provides an information on the safe distance of the nearby equipment to the grounded electrical systems subjected to impulse conditions, but can also identify the right rating of the equipment, particularly sensitive electronic equipment, that are in a vicinity of the ground installations. Further, during the high voltage testing on the ground electrodes at field sites, the results may also be influenced by the electrodes under tests, which can cause inaccuracy in the measurements. This paper presents the computed GPR values for various soil resistivity and ground electrodes. The GPR values are also obtained by the measurement, by injecting high magnitudes of impulse current of both impulse polarities on the ground electrode, and the voltage magnitudes at distances away from the edge of the electrode under impulse are measured. The measurements of GPR allows the investigations on the effect of impulse polarity on these GPR values.