Which fuse designation corresponds to the description: Approach locking stick relay?

• A. Automatic train operation system.
• B. Approach locking stick relay.
• C. Fuse designation.
• D. Prefix for positive DC energy ( high voltage ).

Answer: (B)

This question tests recognizing a specific signaling device by its designation. An approach locking stick relay is a relay used in interlocking to provide approach locking—the mechanism that holds a route locked and prevents changing the signal while a train is approaching or occupying the route. The term “stick relay” refers to a type of relay with a latching, mechanical action, historically used in these interlocking circuits.

So, when the description points to an approach locking stick relay, the fuse designation being asked for is this exact device—a relay that performs approach locking with a stick-type mechanism. This matches the description directly, distinguishing it from broader systems like automatic train operation, a generic “fuse designation,” or a positive DC energy prefix, which do not describe this specific interlocking component.