ST-1 Shutdown

 ST-1 SHUTDOWN PROCEDURE

 (Note-Tie CB means CB for tie between station buses as applicable)

 1. Switch OFF SD bus I/C DC supply . 

2. Ensure SB/SD/UB-3B tie already closed at SB end.

 3. Tie CB to SB/UB-3B CB at SD end, take its selection in manual in CR-1 to check healthiness of “CB in manual “contact by EMD.

 4. Remove tripping of SB end tie CB with help of EMD (otherwise on closing SD end breaker, SB end tie CB will open & fault appear in it in CR-1 . To avoid it, EMD will remove this tripping of SB end tie CB) 5. Close tie CB at SD end . Ensure SB end tie CB will not trip. 

6. Open SB bus I/C from ST-1 . 

7. Normalize tripping ckt at SB end tie CB and DC of SD bus I/C after ensuring no tripping command persisting with help of EMD. 

8. Switch OFF SC bus I/C DC supply. 

9. Take SA/SC/UB-2A tie CB at SA end in manual at CR to check healthiness by EMD. It is normally open. 

10.Remove tripping of SC end tie CB with help of EMD. (Before isolation SA/SC/UB-2A tie close at SC end). 

11.Close SA end tie CB . Ensure SC end tie CB will not trip. 

12.Open SA bus I/C from ST-1 . 

13.Normalize tripping ckt at SC end tie CB and DC of SC bus I/C after ensuring no tripping command persisting with help of EMD. 

14.Rack out & isolate SA & SB incomer breaker from ST-1.

 15.Trip HT Bkr(220 Kv) of ST-1 at switchyard. 

16.Isolate ST-1 from switchyard .