Protection System

First, we will try to understand what LBB is and why it operates. What is LBB? and When does it Operate?  Ans: LBB is a Backup Protection to the Breaker, which operates in case the concerned Circuit Breaker fails to operate in 200 ms, by tripping all the Fault infeeds ( all the Circuit Breakers…

Plug Setting is the Current Setting of the Relay.
It is given by the Percentage of the Relay Nominal Current (In), which when flows through the Relay, the Relay Operates.
Where the Relay Nominal Current (In) is kept the same as the CT Secondary Current which is usually 1A or 5A.
TMS is used to control the Operating Time of the Relay (ROT).