Due to the different operation and maintenance habits of power grid in Brazil

the LOCKOUT relay used in circuit-breaker secondary circuit of Belo Mountain II ±800 kV UHVDC project is different from its application and configuration principles of power grid in China. The differences between Brazil and China about the typical circuit-breaker operation circuit in AC system of UHVDC project are analyzed and compared. Then

the configuration principle for LOCKOUT relay of the circuit-breaker operation circuit in AC system of UHVDC project is put forward

which can meet the operation and maintenance requirements in Brazil. Moreover

taking the circuit-breaker operation circuit in Xingu converter station for example

the start-up and locking logic of LOCKOUT relay are introduced in detail. The proposed configuration principle for LOCKOUT relay is adapted to the construction of power grid in Brazil

and provides a support for the Chinese UHVDC technology to go abroad and service the "Belt and Road" countries.