When there is a malfunction, only tripping will not be "implicated" - revealing selective protection
In the power distribution system, selective protection refers to the action of only the protective device of a branch to cut off the power supply when a fault occurs, while the higher-level protective device remains closed, ensuring that other fault free circuits continue to supply power. The key to achieving selective protection lies in the coordination of action parameters between upper and lower level protective appliances: usually achieved by setting action current values (current selectivity) or action times (time selectivity) in stages. Reasonable selective protection design can minimize the scope of power outages and improve power supply reliability, which is a basic requirement for modern buildings and industrial power distribution.
