Protection on 6 kV Station Board.
Protection on 6 kV Station Board.
(OP)
We Have two Station Service Transformer (SST) to supply our 6,3 kV Station Board A&B on a Coal fired Power Plant. The SST rating is 150 / 6,3 kV and primary side (150kV) supplied from the 150 kV transmission line through GIS (Gas Insulated Switchgear). There was a black out on the system so the SST completely loss the voltage. but on that fault the 6,3 kV Station board incoming CB didn't Trip. The station board itself provide with Bus Under Voltage (27) protection Relay and it works after the SST loss the voltage. But The trip contact did not connencted to the incoming breaker.
My quenstion is : is that a standard that the incoming CB must trip because off loss voltage of the SST (like my example)? because we are affraid of accidental energization if the Transmission line suddenly energize and the station board incoming CB still at close position and all the load are connected. It will shock the busbar.
My quenstion is : is that a standard that the incoming CB must trip because off loss voltage of the SST (like my example)? because we are affraid of accidental energization if the Transmission line suddenly energize and the station board incoming CB still at close position and all the load are connected. It will shock the busbar.





RE: Protection on 6 kV Station Board.
RE: Protection on 6 kV Station Board.
RE: Protection on 6 kV Station Board.
But, I don't know the plant configuration.
We use a lockout on the unit to trip all breakers, and to prevent any of the breakers to close. The problem is once the lockout is reset any breaker may be closed. So the operators should not reset the lockout until the unit is ready to run.
Being this is a power plant and it is desired to keep power to the customers, some loss of motor life should be expected in the way of keeping the unit running. So an under voltage setting of 50% or lower with some time delay is not beyond belief.
Most bus bar is rigid enough that shocking it should not be a problem.
RE: Protection on 6 kV Station Board.
RE: Protection on 6 kV Station Board.