Abstract
Recently digital control panels have been installed for various controls adjacent to GIS. As the distance between the digital control panels and GIS is short, switching surge is transmitted without attenuation. Therefore we developed the digital control panel that implemented surge countermeasure. We verified that the digital control panel adjacent to 500kV GIS did not malfunction for switching surge. Moreover we measured the switching surge at the digital control panel and analyzed the intrusion route of switching surge by EMTP. As a result, we observed that the maximum voltages at a secondary circuit of CT and the maximum voltages at a secondary circuit of VT were 2.4kVp-p and 2.8kVp-p, respectively. The major frequencies of those voltage waveform were distributed almost more than 10MHz. In the EMTP, the intrusion route from the GIS to the secondary circuit of VT was calculated. The voltage waveforms at VT terminal calculated by EMTP agree with measured results in the view point of amplitude, frequency and damping time.
