Device for interlocking the manual actuation of a switch with the help of locks

An interlock device using locks to prevent manual actuation of a switch having a handle inlet, and to allow the switch to be actuated manually in a certain sequence of operations determined by using keys for the locks, thereby enabling the switch to pass from a first switching position to a second switching position, the device comprising a first lock having a first bolt and a second lock having a second bolt each operable by means of at least one key capable of being withdrawn from a corresponding one of the first lock and the second lock or of being engaged in the corresponding lock only when the corresponding lock is in a locked position, a set of cams whose rotation is tied to actuation of the switch, said cams acting on the first and second bolts of said first and second locks, respectively, to prevent the first lock from being operated so long as a second switch is not in a second switching position and to prevent the second lock from being operated by the at least one key as soon as the second switch no longer occupies a first switching position, both the first lock and the second lock being disposed in such a manner that the first and second bolts, respectively, when in an advanced position, close the handle inlet of the switch, the first bolt of the first lock being in a retracted position and the second bolt of the second lock being in the advanced position when the switch is in the first switching position.