Circuit for determining lockout states of lockout relays

The invention discloses a circuit for determining lockout states of lockout relays, which solves the technical problem of correctly determining contact states of the lockout relays. The circuit is respectively provided with an A-phase trip lockout relay, a B-phase trip lockout relay, a C-phase trip lockout relay and a holding relay, a series circuit with large resistors, an A-phase trip circuit supervision optical coupler, a B-phase trip circuit supervision optical coupler and a C-phase trip circuit supervision optical coupler are parallelly connected into a series circuit with contacts of the A-phase trip lockout relay, the B-phase trip lockout relay, the C-phase trip lockout relay and a coil of the holding relay, and the optical couplers are current starting type optical couplers. Compared with the prior art, the circuit has the advantages that the large resistors and the current starting type optical couplers are parallelly connected onto the contacts of the lockout relays, the states are fed back to a CPU (central processing unit) of intelligent terminal equipment, and the intelligent terminal equipment determines whether the lockout relays are correctly closed or not by determining state changes of input of the optical couplers during execution after receiving a protection command of an electric power system and tripping and closing commands of measurement and control equipment, so that the influence of unreliable factors of an autoeciousness circuit on the electric power system is eliminated.