Application of fault location system in power substations

Development of a GIS fault location system

“…On the other hand, the SP relay will make the contact if the pressure wave of the gas section where it is installed or the pressure rise within a fixed time exceeds a certain level [4,5]. Therefore, by installing SP relays in the gas sections of the respective bays, simplified data handling in the system and simplified data processing content will become possible.…”

“…In the case of fault arc currents exceeding 10 kA, shock gas pressure waves will occur when they are relatively large and the SP relay will operate as a result. On the other hand, when the fault arc current is below 10 kA, shock gas pressure waves will not occur and the SP relay will instead operate due to the pressure rise of the entire gas section where the arc has occurred [4,5].…”

“…3 and have investigated the effects. Table 1 shows As to the rise time of the pressure waves, the tests are carried out for the case of a steep wave corresponding to the shock gas pressure wave, and the case of a slow-wave-front wave corresponding to the pressure rise of the entire gas section, in such a way that the results would be as close as possible to the measured results of the pressure variations in the fault arc tests conducted in the past [4,5]; however, for the steep wave, due to the limitations of the test equipment, the tests are carried out with pressure waves of a little slower rise.…”

“…The pressure rise value 'P 2 at the rising portion of the slow-wave-front wave when the arc current is small can be roughly expressed by the following equation, which shows the pressure rise of the entire gas section [5]:…”

“…The sensors applied in the GIS fault location system include the shock gas pressure detection sensor (SP: shock pressure relay), gas pressure sensor, vibration sensor, optical sensor, and magnetic field sensor [13,5]. Among these, the vibration sensor is limited to application to simple shapes such as a GIB (gas-insulated bus) because the propagation of the signal which must be detected will be affected by the shape of the tank and the existence of flanges; the optical sensor is particularly difficult to apply to existing apparatus because it is necessary to install a light-receiving unit inside the tank; and the magnetic-field sensor cannot be applied to the GIS of multipoint grounding systems where the ground-fault current flowing to the tank will have a complex distribution [7].…”