SUB: Distance Relay for 110kv Line-1
In our 110kv Line-1 we have Enertec-Schlumberger, France make Back-up Distance relay (21-B1) for line protection and it was kept out of service from 17.09.02 onwards. Because it was malfunctioned in four/five event for unrelated fault in the Grid. There is an another Distance relay in the same line is called Main Distance relay(21-M1) which is in service. But this relay also was not operated in recent fault. Any way it is to be checked during Annual shut down.
Now servicing of 21-B1 relay is not possible since the company was closed. In our past experience this make of relays slowly gives trouble and same we are replacing one by one. For Line-2 already we have replaced by New ABB make, RAZOA relay (ref. P.O.No.TCP/PP/SPRS/443 dt.31.01.01) in the place of Main Distance Relay (21-M2).
At present in Line-1 there is no sensitive relay to detect Earth Fault, only Back-up to distance Protection is available(Directional O/C & E/F relay) .This relay will operate for the all zone fault in the line. So it is decided to procure new distance relay in the place of 21-B1 and MPR has been raised for the RAZOA, ABB make (MPR No. 2973 dt.26/09/03). You are kindly requested to give an approval to procure the relay as per MPR .