INVESTIGATION OF TRANSIENT OVER VOLTAGE ON STATIC EXCITATION SYSTEM " NEKA "

Neka, a turnkey thermal power plant by M/S Brown Boveri CIE CO. consists of 4x440 MW unit with static excitation system and 400 KV sub-station by MI'S Mitsubishi, is located at 50 metres away from power plant. The schematic is as shown in appendix 'G'. It is observed on unit no. 4 whenever 400 kv isolator are manuered at sub-station caused thyrister and its associated fuses failure due to over voltages and over voltages are also observed on other units. This investigation report just briefs salient features of transient over voltage phenomena, sources and remedial measures for present and future similar static excitation system.